Commit Graph

727 Commits

Author SHA1 Message Date
Gautham R Shenoy 86ef5c9a8e cpu-hotplug: replace lock_cpu_hotplug() with get_online_cpus()
Replace all lock_cpu_hotplug/unlock_cpu_hotplug from the kernel and use
get_online_cpus and put_online_cpus instead as it highlights the
refcount semantics in these operations.

The new API guarantees protection against the cpu-hotplug operation, but
it doesn't guarantee serialized access to any of the local data
structures. Hence the changes needs to be reviewed.

In case of pseries_add_processor/pseries_remove_processor, use
cpu_maps_update_begin()/cpu_maps_update_done() as we're modifying the
cpu_present_map there.

Signed-off-by: Gautham R Shenoy <ego@in.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-25 21:08:02 +01:00
Srivatsa Vaddagiri 6b2d770026 sched: group scheduler, fix fairness of cpu bandwidth allocation for task groups
The current load balancing scheme isn't good enough for precise
group fairness.

For example: on a 8-cpu system, I created 3 groups as under:

	a = 8 tasks (cpu.shares = 1024)
	b = 4 tasks (cpu.shares = 1024)
	c = 3 tasks (cpu.shares = 1024)

a, b and c are task groups that have equal weight. We would expect each
of the groups to receive 33.33% of cpu bandwidth under a fair scheduler.

This is what I get with the latest scheduler git tree:

Signed-off-by: Ingo Molnar <mingo@elte.hu>
--------------------------------------------------------------------------------
Col1  | Col2    | Col3  |  Col4
------|---------|-------|-------------------------------------------------------
a     | 277.676 | 57.8% | 54.1%  54.1%  54.1%  54.2%  56.7%  62.2%  62.8% 64.5%
b     | 116.108 | 24.2% | 47.4%  48.1%  48.7%  49.3%
c     |  86.326 | 18.0% | 47.5%  47.9%  48.5%
--------------------------------------------------------------------------------

Explanation of o/p:

Col1 -> Group name
Col2 -> Cumulative execution time (in seconds) received by all tasks of that
	group in a 60sec window across 8 cpus
Col3 -> CPU bandwidth received by the group in the 60sec window, expressed in
        percentage. Col3 data is derived as:
		Col3 = 100 * Col2 / (NR_CPUS * 60)
Col4 -> CPU bandwidth received by each individual task of the group.
		Col4 = 100 * cpu_time_recd_by_task / 60

[I can share the test case that produces a similar o/p if reqd]

The deviation from desired group fairness is as below:

	a = +24.47%
	b = -9.13%
	c = -15.33%

which is quite high.

After the patch below is applied, here are the results:

--------------------------------------------------------------------------------
Col1  | Col2    | Col3  |  Col4
------|---------|-------|-------------------------------------------------------
a     | 163.112 | 34.0% | 33.2%  33.4%  33.5%  33.5%  33.7%  34.4%  34.8% 35.3%
b     | 156.220 | 32.5% | 63.3%  64.5%  66.1%  66.5%
c     | 160.653 | 33.5% | 85.8%  90.6%  91.4%
--------------------------------------------------------------------------------

Deviation from desired group fairness is as below:

	a = +0.67%
	b = -0.83%
	c = +0.17%

which is far better IMO. Most of other runs have yielded a deviation within
+-2% at the most, which is good.

Why do we see bad (group) fairness with current scheuler?
=========================================================

Currently cpu's weight is just the summation of individual task weights.
This can yield incorrect results. For ex: consider three groups as below
on a 2-cpu system:

	CPU0	CPU1
---------------------------
	A (10)  B(5)
		C(5)
---------------------------

Group A has 10 tasks, all on CPU0, Group B and C have 5 tasks each all
of which are on CPU1. Each task has the same weight (NICE_0_LOAD =
1024).

The current scheme would yield a cpu weight of 10240 (10*1024) for each cpu and
the load balancer will think both CPUs are perfectly balanced and won't
move around any tasks. This, however, would yield this bandwidth:

	A = 50%
	B = 25%
	C = 25%

which is not the desired result.

What's changing in the patch?
=============================

	- How cpu weights are calculated when CONFIF_FAIR_GROUP_SCHED is
	  defined (see below)
	- API Change
		- Two tunables introduced in sysfs (under SCHED_DEBUG) to
		  control the frequency at which the load balance monitor
		  thread runs.

The basic change made in this patch is how cpu weight (rq->load.weight) is
calculated. Its now calculated as the summation of group weights on a cpu,
rather than summation of task weights. Weight exerted by a group on a
cpu is dependent on the shares allocated to it and also the number of
tasks the group has on that cpu compared to the total number of
(runnable) tasks the group has in the system.

Let,
	W(K,i)  = Weight of group K on cpu i
	T(K,i)  = Task load present in group K's cfs_rq on cpu i
	T(K)    = Total task load of group K across various cpus
	S(K) 	= Shares allocated to group K
	NRCPUS	= Number of online cpus in the scheduler domain to
	 	  which group K is assigned.

Then,
	W(K,i) = S(K) * NRCPUS * T(K,i) / T(K)

A load balance monitor thread is created at bootup, which periodically
runs and adjusts group's weight on each cpu. To avoid its overhead, two
min/max tunables are introduced (under SCHED_DEBUG) to control the rate
at which it runs.

Fixes from: Peter Zijlstra <a.p.zijlstra@chello.nl>

- don't start the load_balance_monitor when there is only a single cpu.
- rename the kthread because its currently longer than TASK_COMM_LEN

Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-25 21:08:00 +01:00
Srivatsa Vaddagiri a183561567 sched: introduce a mutex and corresponding API to serialize access to doms_curarray
doms_cur[] array represents various scheduling domains which are
mutually exclusive. Currently cpusets code can modify this array (by
calling partition_sched_domains()) as a result of user modifying
sched_load_balance flag for various cpusets.

This patch introduces a mutex and corresponding API (only when
CONFIG_FAIR_GROUP_SCHED is defined) which allows a reader to safely read
the doms_cur[] array w/o worrying abt concurrent modifications to the
array.

The fair group scheduler code (introduced in next patch of this series)
makes use of this mutex to walk thr' doms_cur[] array while rebalancing
shares of task groups across cpus.

Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-25 21:08:00 +01:00
Srivatsa Vaddagiri 58e2d4ca58 sched: group scheduling, change how cpu load is calculated
This patch changes how the cpu load exerted by fair_sched_class tasks
is calculated. Load exerted by fair_sched_class tasks on a cpu is now
a summation of the group weights, rather than summation of task weights.
Weight exerted by a group on a cpu is dependent on the shares allocated
to it.

This version of patch has a minor impact on code size, but should have
no runtime/functional impact for !CONFIG_FAIR_GROUP_SCHED.

Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-25 21:08:00 +01:00
Srivatsa Vaddagiri ec2c507fe8 sched: group scheduling, minor fixes
Minor bug fixes for the group scheduler:

- Use a mutex to serialize add/remove of task groups and also when
  changing shares of a task group. Use the same mutex when printing
  cfs_rq debugging stats for various task groups.

- Use list_for_each_entry_rcu in for_each_leaf_cfs_rq macro (when
  walking task group list)

Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-25 21:07:59 +01:00
Srivatsa Vaddagiri 93f992ccc0 sched: group scheduling code cleanup
Minor cleanups:

- Fix coding style
- remove obsolete comment

Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-25 21:07:59 +01:00
Ingo Molnar c61935fd0e sched: group scheduler, set uid share fix
setting cpu share to 1 causes hangs, as reported in:

    http://bugzilla.kernel.org/show_bug.cgi?id=9779

as the default share is 1024, the values of 0 and 1 can indeed
cause problems. Limit it to 2 or higher values.

These values can only be set by the root user - but still it
makes sense to protect against nonsensical values.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-22 11:24:58 +01:00
Roland McGrath fcfd50afb6 show_task: real_parent
The show_task function invoked by sysrq-t et al displays the
pid and parent's pid of each task.  It seems more useful to
show the actual process hierarchy here than who is using
ptrace on each process.

Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-01-09 08:03:58 -08:00
Ingo Molnar 2bacec8c31 sched: touch softlockup watchdog after idling
touch softlockup watchdog after idling.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-12-18 15:21:13 +01:00
Dmitry Adamushko 051a1d1afa sched: fix crash on ia64, introduce task_current()
Some services (e.g. sched_setscheduler(), rt_mutex_setprio() and
sched_move_task()) must handle a given task differently in case it's the
'rq->curr' task on its run-queue. The task_running() interface is not
suitable for determining such tasks for platforms with one of the
following options:

#define __ARCH_WANT_UNLOCKED_CTXSW
#define __ARCH_WANT_INTERRUPTS_ON_CTXSW

Due to the fact that it makes use of 'p->oncpu == 1' as a criterion but
such a task is not necessarily 'rq->curr'.

The detailed explanation is available here:
https://lists.linux-foundation.org/pipermail/containers/2007-December/009262.html

Signed-off-by: Dmitry Adamushko <dmitry.adamushko@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Tested-by: Dhaval Giani <dhaval@linux.vnet.ibm.com>
Tested-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
2007-12-18 15:21:13 +01:00
Ingo Molnar 8ced5f69e4 sched: enable early use of sched_clock()
some platforms have sched_clock() implementations that cannot be called
very early during wakeup. If it's called it might hang or crash in hard
to debug ways. So only call update_rq_clock() [which calls sched_clock()]
if sched_init() has already been called. (rq->idle is NULL before the
scheduler is initialized.)

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-12-07 19:02:47 +01:00
Matthew Wilcox 009e577e07 Add wait_for_completion_killable
Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
2007-12-06 17:40:19 -05:00
Matthew Wilcox d9514f6c6b sched: Use task_contributes_to_load, TASK_ALL and TASK_NORMAL
Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
2007-12-06 17:34:59 -05:00
Ingo Molnar 41a2d6cfa3 sched: style cleanups
style cleanup of various changes that were done recently.

no code changed:

      text    data     bss     dec     hex filename
     23680    2542      28   26250    668a sched.o.before
     23680    2542      28   26250    668a sched.o.after

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-12-05 15:46:09 +01:00
Ingo Molnar 77034937dc sched: fix crash in sys_sched_rr_get_interval()
Luiz Fernando N. Capitulino reported that sched_rr_get_interval()
crashes for SCHED_OTHER tasks that are on an idle runqueue.

The fix is to return a 0 timeslice for tasks that are on an idle
runqueue. (and which are not running, obviously)

this also shrinks the code a bit:

   text    data     bss     dec     hex filename
  47903    3934     336   52173    cbcd sched.o.before
  47885    3934     336   52155    cbbb sched.o.after

Reported-by: Luiz Fernando N. Capitulino <lcapitulino@mandriva.com.br>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-12-04 17:04:39 +01:00
Srivatsa Vaddagiri d842de871c sched: cpu accounting controller (V2)
Commit cfb5285660 removed a useful feature for
us, which provided a cpu accounting resource controller.  This feature would be
useful if someone wants to group tasks only for accounting purpose and doesnt
really want to exercise any control over their cpu consumption.

The patch below reintroduces the feature. It is based on Paul Menage's
original patch (Commit 62d0df6406), with
these differences:

        - Removed load average information. I felt it needs more thought (esp
	  to deal with SMP and virtualized platforms) and can be added for
	  2.6.25 after more discussions.
        - Convert group cpu usage to be nanosecond accurate (as rest of the cfs
	  stats are) and invoke cpuacct_charge() from the respective scheduler
	  classes
	- Make accounting scalable on SMP systems by splitting the usage
	  counter to be per-cpu
	- Move the code from kernel/cpu_acct.c to kernel/sched.c (since the
	  code is not big enough to warrant a new file and also this rightly
	  needs to live inside the scheduler. Also things like accessing
	  rq->lock while reading cpu usage becomes easier if the code lived in
	  kernel/sched.c)

The patch also modifies the cpu controller not to provide the same accounting
information.

Tested-by: Balbir Singh <balbir@linux.vnet.ibm.com>

 Tested the patches on top of 2.6.24-rc3. The patches work fine. Ran
 some simple tests like cpuspin (spin on the cpu), ran several tasks in
 the same group and timed them. Compared their time stamps with
 cpuacct.usage.

Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-12-02 20:04:49 +01:00
Ingo Molnar deaf2227dd sched: clean up, move __sched_text_start/end to sched.h
move __sched_text_start/end to sched.h. No code changed:

   text    data     bss     dec     hex filename
  26582    2310      28   28920    70f8 sched.o.before
  26582    2310      28   28920    70f8 sched.o.after

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-11-28 15:52:56 +01:00
Ingo Molnar 9a4e715914 sched: clean up sd_alloc_ctl_cpu_table() definition
clean up sd_alloc_ctl_cpu_table() definition.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-11-28 15:52:56 +01:00
Ingo Molnar 9612633a21 sched: reorder SCHED_FEAT_ bits
reorder SCHED_FEAT_ bits so that the used ones come first. Makes
tuning instructions easier.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-11-15 20:57:40 +01:00
Dmitry Adamushko 94bc9a7bd9 sched: remove activate_idle_task()
cpu_down() code is ok wrt sched_idle_next() placing the 'idle' task not
at the beginning of the queue.

So get rid of activate_idle_task() and make use of activate_task() instead.
It is the same as activate_task(), except for the update_rq_clock(rq) call
that is redundant.

Code size goes down:

   text    data     bss     dec     hex filename
  47853    3934     336   52123    cb9b sched.o.before
  47828    3934     336   52098    cb82 sched.o.after

Signed-off-by: Dmitry Adamushko <dmitry.adamushko@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-11-15 20:57:40 +01:00
Dmitry Adamushko ce96b5ac74 sched: fix __set_task_cpu() SMP race
Grant Wilson has reported rare SCHED_FAIR_USER crashes on his quad-core
system, which crashes can only be explained via runqueue corruption.

there is a narrow SMP race in __set_task_cpu(): after ->cpu is set up to
a new value, task_rq_lock(p, ...) can be successfuly executed on another
CPU. We must ensure that updates of per-task data have been completed by
this moment.

this bug has been hiding in the Linux scheduler for an eternity (we never
had any explicit barrier for task->cpu in set_task_cpu() - so the bug was
introduced in 2.5.1), but only became visible via set_task_cfs_rq() being
accidentally put after the task->cpu update. It also probably needs a
sufficiently out-of-order CPU to trigger.

Reported-by: Grant Wilson <grant.wilson@zen.co.uk>
Signed-off-by: Dmitry Adamushko <dmitry.adamushko@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-11-15 20:57:40 +01:00
Oleg Nesterov dae51f5620 sched: fix SCHED_FIFO tasks & FAIR_GROUP_SCHED
Suppose that the SCHED_FIFO task does

	switch_uid(new_user);

Now, p->se.cfs_rq and p->se.parent both point into the old
user_struct->tg because sched_move_task() doesn't call set_task_cfs_rq()
for !fair_sched_class case.

Suppose that old user_struct/task_group is freed/reused, and the task
does

	sched_setscheduler(SCHED_NORMAL);

__setscheduler() sets fair_sched_class, but doesn't update
->se.cfs_rq/parent which point to the freed memory.

This means that check_preempt_wakeup() doing

		while (!is_same_group(se, pse)) {
			se = parent_entity(se);
			pse = parent_entity(pse);
		}

may OOPS in a similar way if rq->curr or p did something like above.

Perhaps we need something like the patch below, note that
__setscheduler() can't do set_task_cfs_rq().

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-11-15 20:57:40 +01:00
Christian Borntraeger 9778385db3 sched: fix accounting of interrupts during guest execution on s390
Currently the scheduler checks for PF_VCPU to decide if this timeslice
has to be accounted as guest time. On s390 host interrupts are not
disabled during guest execution. This causes theses interrupts to be
accounted as guest time if CONFIG_VIRT_CPU_ACCOUNTING is set. Solution
is to check if an interrupt triggered account_system_time. As the tick
is timer interrupt based, we have to subtract hardirq_offset.

I tested the patch on s390 with CONFIG_VIRT_CPU_ACCOUNTING and on
x86_64. Seems to work.

CC: Avi Kivity <avi@qumranet.com>
CC: Laurent Vivier <Laurent.Vivier@bull.net>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-11-15 20:57:39 +01:00
Andrew Morton cfb5285660 revert "Task Control Groups: example CPU accounting subsystem"
Revert 62d0df6406.

This was originally intended as a simple initial example of how to create a
control groups subsystem; it wasn't intended for mainline, but I didn't make
this clear enough to Andrew.

The CFS cgroup subsystem now has better functionality for the per-cgroup usage
accounting (based directly on CFS stats) than the "usage" status file in this
patch, and the "load" status file is rather simplistic - although having a
per-cgroup load average report would be a useful feature, I don't believe this
patch actually provides it.  If it gets into the final 2.6.24 we'd probably
have to support this interface for ever.

Cc: Paul Menage <menage@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-11-14 18:45:40 -08:00
Adrian Bunk e6fe6649b4 sched: proper prototype for kernel/sched.c:migration_init()
This patch adds a proper prototype for migration_init() in
include/linux/sched.h

Since there's no point in always returning 0 to a caller that doesn't check
the return value it also changes the function to return void.

Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-11-09 22:39:39 +01:00
Peter Zijlstra b82d9fdd84 sched: avoid large irq-latencies in smp-balancing
SMP balancing is done with IRQs disabled and can iterate the full rq.
When rqs are large this can cause large irq-latencies. Limit the nr of
iterations on each run.

This fixes a scheduling latency regression reported by the -rt folks.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Tested-by: Gregory Haskins <ghaskins@novell.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-11-09 22:39:39 +01:00
Ingo Molnar 3e3e13f399 sched: remove PREEMPT_RESTRICT
remove PREEMPT_RESTRICT. (this is a separate commit so that any
regression related to the removal itself is bisectable)

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-11-09 22:39:39 +01:00
Ingo Molnar 52d3da1ad4 sched: turn off PREEMPT_RESTRICT
PREEMPT_RESTRICT was a method aimed at reducing the amount of wakeup
related preemption. It has a disadvantage though, it can prevent
legitimate wakeups if a task is 'unlucky' to be hit too early by a tick
that clears peer_preempt.

Now that the wakeup preemption has been cleaned up we dont seem to have
excessive preemptions anymore, so this feature can be turned off. (and
removed in the next patch)

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-11-09 22:39:39 +01:00
Eric Dumazet d6322faf29 sched: cleanup, use NSEC_PER_MSEC and NSEC_PER_SEC
1) hardcoded 1000000000 value is used five times in places where
   NSEC_PER_SEC might be more readable.

2) A conversion from nsec to msec uses the hardcoded 1000000 value,
   which is a candidate for NSEC_PER_MSEC.

no code changed:

    text    data     bss     dec     hex filename
   44359    3326      36   47721    ba69 sched.o.before
   44359    3326      36   47721    ba69 sched.o.after

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-11-09 22:39:38 +01:00
Ingo Molnar 19978ca610 sched: reintroduce SMP tunings again
Yanmin Zhang reported an aim7 regression and bisected it down to:

 |  commit 38ad464d41
 |  Author: Ingo Molnar <mingo@elte.hu>
 |  Date:   Mon Oct 15 17:00:02 2007 +0200
 |
 |     sched: uniform tunings
 |
 |     use the same defaults on both UP and SMP.

fix this by reintroducing similar SMP tunings again. This resolves
the regression.

(also update the comments to match the ilog2(nr_cpus) tuning effect)

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-11-09 22:39:38 +01:00
Ingo Molnar 38605cae99 sched: fix style in kernel/sched.c
fallout of recent commits: small coding style fixes.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-29 21:18:11 +01:00
Paul Menage fe5c7cc228 sched: report CPU usage in CFS cgroup directories
Adds a cpu.usage file to the CFS cgroup that reports CPU usage in
milliseconds for that cgroup's tasks

[ mingo@elte.hu: style cleanups. ]

Signed-off-by: Paul Menage <menage@google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-29 21:18:11 +01:00
Srivatsa Vaddagiri ae8393e508 sched: move rcu_head to task_group struct
Peter Zijlstra noticed that the rcu_head object need not be present
in every cfs_rq of a group. Move it to the task_group structure
instead.

Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-29 21:18:11 +01:00
James Bottomley 7bae49d498 sched: fix incorrect assumption that cpu 0 exists
This patch:

commit 9b5b77512d
Author: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Date:   Mon Oct 15 17:00:09 2007 +0200

    sched: clean up code under CONFIG_FAIR_GROUP_SCHED

Introduced an assumption of the existence of CPU0 via this line

cfs_rq = tg->cfs_rq[0];

If you have no CPU0, that will be NULL.  The fix seems to be just to
take whatever cfs_rq queue comes out of the for_each_possible_cpu()
loop, since they're all equally good for the destruction operation.

Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-29 21:18:11 +01:00
Adrian Bunk f7402e0361 sched: make kernel/sched.c:account_guest_time() static
account_guest_time() can become static.

Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-29 21:18:10 +01:00
Peter Williams 681f3e6854 sched: isolate SMP balancing code a bit more
At the moment, a lot of load balancing code that is irrelevant to non
SMP systems gets included during non SMP builds.

This patch addresses this issue and reduces the binary size on non
SMP systems:

   text    data     bss     dec     hex filename
  10983      28    1192   12203    2fab sched.o.before
  10739      28    1192   11959    2eb7 sched.o.after

Signed-off-by: Peter Williams <pwil3058@bigpond.net.au>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-24 18:23:51 +02:00
Peter Williams e1d1484f72 sched: reduce balance-tasks overhead
At the moment, balance_tasks() provides low level functionality for both
  move_tasks() and move_one_task() (indirectly) via the load_balance()
function (in the sched_class interface) which also provides dual
functionality.  This dual functionality complicates the interfaces and
internal mechanisms and makes the run time overhead of operations that
are called with two run queue locks held.

This patch addresses this issue and reduces the overhead of these
operations.

Signed-off-by: Peter Williams <pwil3058@bigpond.net.au>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-24 18:23:51 +02:00
Paul Menage 2b01dfe372 sched: clean up some control group code
- replace "cont" with "cgrp" in a few places in the CFS cgroup code, 
- use write_uint rather than write for cpu.shares write function

Signed-off-by: Paul Menage <menage@google.com>
Acked-by : Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-24 18:23:50 +02:00
Satyam Sharma 838225b48e sched: use show_regs() to improve __schedule_bug() output
A full register dump along with stack backtrace would make the
"scheduling while atomic" message more helpful. Use show_regs() instead
of dump_stack() for this. We already know we're atomic in here (that is
why this function was called) so show_regs()'s atomicity expectations
are guaranteed.

Also, modify the output of the "BUG: scheduling while atomic:" header a
bit to keep task->comm and task->pid together and preempt_count() after
them.

Signed-off-by: Satyam Sharma <satyam@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-24 18:23:50 +02:00
Ingo Molnar 4dcf6aff02 sched: clean up sched_domain_debug()
clean up sched_domain_debug().

this also shrinks the code a bit:

   text    data     bss     dec     hex filename
  50474    4306     480   55260    d7dc sched.o.before
  50404    4306     480   55190    d796 sched.o.after

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-24 18:23:48 +02:00
Ingo Molnar b15136e949 sched: fix fastcall mismatch in completion APIs
Jeff Dike noticed that wait_for_completion_interruptible()'s prototype
had a mismatched fastcall.

Fix this by removing the fastcall attributes from all the completion APIs.

Found-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-24 18:23:48 +02:00
Milton Miller 7378547f2c sched: fix sched_domain sysctl registration again
commit  029190c515 (cpuset
sched_load_balance flag) was not tested SCHED_DEBUG enabled as
committed as it dereferences NULL when used and it reordered
the sysctl registration to cause it to never show any domains
or their tunables.

Fixes:

1) restore arch_init_sched_domains ordering
	we can't walk the domains before we build them

	presently we register cpus with empty directories (no domain
	directories or files).

2) make unregister_sched_domain_sysctl do nothing when already unregistered
	detach_destroy_domains is now called one set of cpus at a time
	unregister_syctl dereferences NULL if called with a null.

	While the the function would always dereference null if called
	twice, in the previous code it was always called once and then
	was followed a register.  So only the hidden bug of the
	sysctl_root_table not being allocated followed by an attempt to
	free it would have shown the error.

3) always call unregister and register in partition_sched_domains
	The code is "smart" about unregistering only needed domains.
	Since we aren't guaranteed any calls to unregister, always 
	unregister.   Without calling register on the way out we
	will not have a table or any sysctl tree.

4) warn if register is called without unregistering
	The previous table memory is lost, leaving pointers to the
	later freed memory in sysctl and leaking the memory of the
	tables.

Before this patch on a 2-core 4-thread box compiled for SMT and NUMA,
the domains appear empty (there are actually 3 levels per cpu).  And as
soon as two domains a null pointer is dereferenced (unreliable in this
case is stack garbage):

bu19a:~# ls -R /proc/sys/kernel/sched_domain/
/proc/sys/kernel/sched_domain/:
cpu0  cpu1  cpu2  cpu3

/proc/sys/kernel/sched_domain/cpu0:

/proc/sys/kernel/sched_domain/cpu1:

/proc/sys/kernel/sched_domain/cpu2:

/proc/sys/kernel/sched_domain/cpu3:

bu19a:~# mkdir /dev/cpuset
bu19a:~# mount -tcpuset cpuset /dev/cpuset/
bu19a:~# cd /dev/cpuset/
bu19a:/dev/cpuset# echo 0 > sched_load_balance 
bu19a:/dev/cpuset# mkdir one
bu19a:/dev/cpuset# echo 1 > one/cpus               
bu19a:/dev/cpuset# echo 0 > one/sched_load_balance 
Unable to handle kernel paging request for data at address 0x00000018
Faulting instruction address: 0xc00000000006b608
NIP: c00000000006b608 LR: c00000000006b604 CTR: 0000000000000000
REGS: c000000018d973f0 TRAP: 0300   Not tainted  (2.6.23-bml)
MSR: 9000000000009032 <EE,ME,IR,DR>  CR: 28242442  XER: 00000000
DAR: 0000000000000018, DSISR: 0000000040000000
TASK = c00000001912e340[1987] 'bash' THREAD: c000000018d94000 CPU: 2
..
NIP [c00000000006b608] .unregister_sysctl_table+0x38/0x110
LR [c00000000006b604] .unregister_sysctl_table+0x34/0x110
Call Trace:
[c000000018d97670] [c000000007017270] 0xc000000007017270 (unreliable)
[c000000018d97720] [c000000000058710] .detach_destroy_domains+0x30/0xb0
[c000000018d977b0] [c00000000005cf1c] .partition_sched_domains+0x1bc/0x230
[c000000018d97870] [c00000000009fdc4] .rebuild_sched_domains+0xb4/0x4c0
[c000000018d97970] [c0000000000a02e8] .update_flag+0x118/0x170
[c000000018d97a80] [c0000000000a1768] .cpuset_common_file_write+0x568/0x820
[c000000018d97c00] [c00000000009d95c] .cgroup_file_write+0x7c/0x180
[c000000018d97cf0] [c0000000000e76b8] .vfs_write+0xe8/0x1b0
[c000000018d97d90] [c0000000000e810c] .sys_write+0x4c/0x90
[c000000018d97e30] [c00000000000852c] syscall_exit+0x0/0x40

Signed-off-by: Milton Miller <miltonm@bga.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-24 18:23:48 +02:00
Laurent Vivier 83d87d1673 sched: don't clear PF_VCPU in scheduler
KVM clears it by itself now, and for s390 this is plain wrong.

Signed-off-by: Laurent Vivier <Laurent.Vivier@bull.net>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Avi Kivity <avi@qumranet.com>
2007-10-22 12:03:29 +02:00
Michael Neuling 6888c1ecd6 kernel/sched.c: remove bogus comment from account_user_time
hardirq_offset is no longer needed.

Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Adrian Bunk <bunk@kernel.org>
2007-10-20 01:41:05 +02:00
Robert P. J. Day 3a4fa0a25d Fix misspellings of "system", "controller", "interrupt" and "necessary".
Fix the various misspellings of "system", controller", "interrupt" and
"[un]necessary".

Signed-off-by: Robert P. J. Day <rpjday@mindspring.com>
Signed-off-by: Adrian Bunk <bunk@kernel.org>
2007-10-19 23:10:43 +02:00
Srivatsa Vaddagiri 68318b8e0b Hook up group scheduler with control groups
Enable "cgroup" (formerly containers) based fair group scheduling.  This
will let administrator create arbitrary groups of tasks (using "cgroup"
pseudo filesystem) and control their cpu bandwidth usage.

[akpm@linux-foundation.org: fix cpp condition]
Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: Dhaval Giani <dhaval@linux.vnet.ibm.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Paul Menage <menage@google.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 11:53:51 -07:00
Cliff Wickman 470fd64644 hotplug cpu: migrate a task within its cpuset
When a cpu is disabled, move_task_off_dead_cpu() is called for tasks that have
been running on that cpu.

Currently, such a task is migrated:
 1) to any cpu on the same node as the disabled cpu, which is both online
    and among that task's cpus_allowed
 2) to any cpu which is both online and among that task's cpus_allowed

It is typical of a multithreaded application running on a large NUMA system to
have its tasks confined to a cpuset so as to cluster them near the memory that
they share.  Furthermore, it is typical to explicitly place such a task on a
specific cpu in that cpuset.  And in that case the task's cpus_allowed
includes only a single cpu.

This patch would insert a preference to migrate such a task to some cpu within
its cpuset (and set its cpus_allowed to its entire cpuset).

With this patch, migrate the task to:
 1) to any cpu on the same node as the disabled cpu, which is both online
    and among that task's cpus_allowed
 2) to any online cpu within the task's cpuset
 3) to any cpu which is both online and among that task's cpus_allowed

In order to do this, move_task_off_dead_cpu() must make a call to
cpuset_cpus_allowed_locked(), a new subset of cpuset_cpus_allowed(), that will
not block.  (name change - per Oleg's suggestion)

Calls are made to cpuset_lock() and cpuset_unlock() in migration_call() to set
the cpuset mutex during the whole migrate_live_tasks() and
migrate_dead_tasks() procedure.

[akpm@linux-foundation.org: build fix]
[pj@sgi.com: Fix indentation and spacing]
Signed-off-by: Cliff Wickman <cpw@sgi.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: Paul Jackson <pj@sgi.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Paul Jackson <pj@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 11:53:44 -07:00
Pavel Emelyanov ba25f9dcc4 Use helpers to obtain task pid in printks
The task_struct->pid member is going to be deprecated, so start
using the helpers (task_pid_nr/task_pid_vnr/task_pid_nr_ns) in
the kernel.

The first thing to start with is the pid, printed to dmesg - in
this case we may safely use task_pid_nr(). Besides, printks produce
more (much more) than a half of all the explicit pid usage.

[akpm@linux-foundation.org: git-drm went and changed lots of stuff]
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Cc: Dave Airlie <airlied@linux.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 11:53:43 -07:00
Eugene Teo 270f722d4d Fix tsk->exit_state usage
tsk->exit_state can only be 0, EXIT_ZOMBIE, or EXIT_DEAD.  A non-zero test
is the same as tsk->exit_state & (EXIT_ZOMBIE | EXIT_DEAD), so just testing
tsk->exit_state is sufficient.

Signed-off-by: Eugene Teo <eugeneteo@kernel.sg>
Cc: Roland McGrath <roland@redhat.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 11:53:42 -07:00
Paul Menage 8707d8b8c0 Fix cpusets update_cpumask
Cause writes to cpuset "cpus" file to update cpus_allowed for member tasks:

- collect batches of tasks under tasklist_lock and then call
  set_cpus_allowed() on them outside the lock (since this can sleep).

- add a simple generic priority heap type to allow efficient collection
  of batches of tasks to be processed without duplicating or missing any
  tasks in subsequent batches.

- make "cpus" file update a no-op if the mask hasn't changed

- fix race between update_cpumask() and sched_setaffinity() by making
  sched_setaffinity() post-check that it's not running on any cpus outside
  cpuset_cpus_allowed().

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Paul Menage <menage@google.com>
Cc: Paul Jackson <pj@sgi.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Cedric Le Goater <clg@fr.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 11:53:41 -07:00
Paul Jackson 029190c515 cpuset sched_load_balance flag
Add a new per-cpuset flag called 'sched_load_balance'.

When enabled in a cpuset (the default value) it tells the kernel scheduler
that the scheduler should provide the normal load balancing on the CPUs in
that cpuset, sometimes moving tasks from one CPU to a second CPU if the
second CPU is less loaded and if that task is allowed to run there.

When disabled (write "0" to the file) then it tells the kernel scheduler
that load balancing is not required for the CPUs in that cpuset.

Now even if this flag is disabled for some cpuset, the kernel may still
have to load balance some or all the CPUs in that cpuset, if some
overlapping cpuset has its sched_load_balance flag enabled.

If there are some CPUs that are not in any cpuset whose sched_load_balance
flag is enabled, the kernel scheduler will not load balance tasks to those
CPUs.

Moreover the kernel will partition the 'sched domains' (non-overlapping
sets of CPUs over which load balancing is attempted) into the finest
granularity partition that it can find, while still keeping any two CPUs
that are in the same shed_load_balance enabled cpuset in the same element
of the partition.

This serves two purposes:
 1) It provides a mechanism for real time isolation of some CPUs, and
 2) it can be used to improve performance on systems with many CPUs
    by supporting configurations in which load balancing is not done
    across all CPUs at once, but rather only done in several smaller
    disjoint sets of CPUs.

This mechanism replaces the earlier overloading of the per-cpuset
flag 'cpu_exclusive', which overloading was removed in an earlier
patch: cpuset-remove-sched-domain-hooks-from-cpusets

See further the Documentation and comments in the code itself.

[akpm@linux-foundation.org: don't be weird]
Signed-off-by: Paul Jackson <pj@sgi.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 11:53:41 -07:00
Pavel Emelyanov 228ebcbe63 Uninline find_task_by_xxx set of functions
The find_task_by_something is a set of macros are used to find task by pid
depending on what kind of pid is proposed - global or virtual one.  All of
them are wrappers above the most generic one - find_task_by_pid_type_ns() -
and just substitute some args for it.

It turned out, that dereferencing the current->nsproxy->pid_ns construction
and pushing one more argument on the stack inline cause kernel text size to
grow.

This patch moves all this stuff out-of-line into kernel/pid.c.  Together
with the next patch it saves a bit less than 400 bytes from the .text
section.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Paul Menage <menage@google.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 11:53:40 -07:00
Pavel Emelyanov b488893a39 pid namespaces: changes to show virtual ids to user
This is the largest patch in the set. Make all (I hope) the places where
the pid is shown to or get from user operate on the virtual pids.

The idea is:
 - all in-kernel data structures must store either struct pid itself
   or the pid's global nr, obtained with pid_nr() call;
 - when seeking the task from kernel code with the stored id one
   should use find_task_by_pid() call that works with global pids;
 - when showing pid's numerical value to the user the virtual one
   should be used, but however when one shows task's pid outside this
   task's namespace the global one is to be used;
 - when getting the pid from userspace one need to consider this as
   the virtual one and use appropriate task/pid-searching functions.

[akpm@linux-foundation.org: build fix]
[akpm@linux-foundation.org: nuther build fix]
[akpm@linux-foundation.org: yet nuther build fix]
[akpm@linux-foundation.org: remove unneeded casts]
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Alexey Dobriyan <adobriyan@openvz.org>
Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Paul Menage <menage@google.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 11:53:40 -07:00
Paul Menage 62d0df6406 Task Control Groups: example CPU accounting subsystem
This example demonstrates how to use the generic cgroup subsystem for a
simple resource tracker that counts, for the processes in a cgroup, the
total CPU time used and the %CPU used in the last complete 10 second interval.

Portions contributed by Balbir Singh <balbir@in.ibm.com>

Signed-off-by: Paul Menage <menage@google.com>
Cc: Serge E. Hallyn <serue@us.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Paul Jackson <pj@sgi.com>
Cc: Kirill Korotaev <dev@openvz.org>
Cc: Herbert Poetzl <herbert@13thfloor.at>
Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com>
Cc: Cedric Le Goater <clg@fr.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 11:53:36 -07:00
Linus Torvalds 54e840dd50 Merge git://git.kernel.org/pub/scm/linux/kernel/git/mingo/linux-2.6-sched
* git://git.kernel.org/pub/scm/linux/kernel/git/mingo/linux-2.6-sched:
  sched: reduce schedstat variable overhead a bit
  sched: add KERN_CONT annotation
  sched: cleanup, make struct rq comments more consistent
  sched: cleanup, fix spacing
  sched: fix return value of wait_for_completion_interruptible()
2007-10-18 14:54:03 -07:00
Michael Neuling c66f08be7e Add scaled time to taskstats based process accounting
This adds items to the taststats struct to account for user and system
time based on scaling the CPU frequency and instruction issue rates.

Adds account_(user|system)_time_scaled callbacks which architectures
can use to account for time using this mechanism.

Signed-off-by: Michael Neuling <mikey@neuling.org>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Jay Lan <jlan@engr.sgi.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-18 14:37:28 -07:00
Ken Chen 480b9434c5 sched: reduce schedstat variable overhead a bit
schedstat is useful in investigating CPU scheduler behavior.  Ideally,
I think it is beneficial to have it on all the time.  However, the
cost of turning it on in production system is quite high, largely due
to number of events it collects and also due to its large memory
footprint.

Most of the fields probably don't need to be full 64-bit on 64-bit
arch.  Rolling over 4 billion events will most like take a long time
and user space tool can be made to accommodate that.  I'm proposing
kernel to cut back most of variable width on 64-bit system.  (note,
the following patch doesn't affect 32-bit system).

Signed-off-by: Ken Chen <kenchen@google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-18 21:32:56 +02:00
Ingo Molnar cc4ea79588 sched: add KERN_CONT annotation
printk: add the KERN_CONT annotation (which is empty string but via
which checkpatch.pl can notice that the lacking KERN_ level is fine).

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-18 21:32:56 +02:00
Ingo Molnar d801649162 sched: cleanup, make struct rq comments more consistent
cleanup, make struct rq comments more consistent.

found via scripts/checkpatch.pl.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-18 21:32:55 +02:00
Ingo Molnar 8401f77505 sched: cleanup, fix spacing
cleanup: fix sysctl_sched_features initialization spacing, and
fix sd_alloc_ctl_cpu_table() prototype spacing.

found via scripts/checkpatch.pl.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-18 21:32:55 +02:00
Andi Kleen 51e9799023 sched: fix return value of wait_for_completion_interruptible()
The recent wait_for_completion() cleanups:

    commit 8cbbe86dfc
    Author: Andi Kleen <ak@suse.de>
    Date:   Mon Oct 15 17:00:14 2007 +0200

    sched: cleanup: refactor common code of sleep_on / wait_for_completion

    Refactor common code of sleep_on / wait_for_completion

broke the return value of wait_for_completion_interruptible().
Previously it returned 0 on success, now -1.  Fix that.

Problem found by Geert Uytterhoeven.

[ mingo: fixed whitespace damage ]

Reported-by: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-18 21:32:55 +02:00
Linus Torvalds e6d5a11dad Merge git://git.kernel.org/pub/scm/linux/kernel/git/mingo/linux-2.6-sched
* git://git.kernel.org/pub/scm/linux/kernel/git/mingo/linux-2.6-sched:
  sched: fix new task startup crash
  sched: fix !SYSFS build breakage
  sched: fix improper load balance across sched domain
  sched: more robust sd-sysctl entry freeing
2007-10-17 09:11:18 -07:00
Oleg Nesterov d2da272a4e migration_call(CPU_DEAD): use spin_lock_irq() instead of task_rq_lock()
Change migration_call(CPU_DEAD) to use direct spin_lock_irq() instead of
task_rq_lock(rq->idle), rq->idle can't change its task_rq().

This makes the code a bit more symmetrical with migrate_dead_tasks()'s path
which uses spin_lock_irq/spin_unlock_irq.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Cliff Wickman <cpw@sgi.com>
Cc: Gautham R Shenoy <ego@in.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com>
Cc: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-17 08:43:03 -07:00
Oleg Nesterov f7b4cddcc5 do CPU_DEAD migrating under read_lock(tasklist) instead of write_lock_irq(tasklist)
Currently move_task_off_dead_cpu() is called under
write_lock_irq(tasklist).  This means it can't use task_lock() which is
needed to improve migrating to take task's ->cpuset into account.

Change the code to call move_task_off_dead_cpu() with irqs enabled, and
change migrate_live_tasks() to use read_lock(tasklist).

This all is a preparation for the futher changes proposed by Cliff Wickman, see
	http://marc.info/?t=117327786100003

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Cliff Wickman <cpw@sgi.com>
Cc: Gautham R Shenoy <ego@in.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com>
Cc: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-17 08:43:03 -07:00
Srivatsa Vaddagiri b9dca1e0fc sched: fix new task startup crash
Child task may be added on a different cpu that the one on which parent
is running. In which case, task_new_fair() should check whether the new
born task's parent entity should be added as well on the cfs_rq.

Patch below fixes the problem in task_new_fair.

This could fix the put_prev_task_fair() crashes reported.

Reported-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Reported-by: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-17 16:55:11 +02:00
Ken Chen 908a7c1b9b sched: fix improper load balance across sched domain
We recently discovered a nasty performance bug in the kernel CPU load
balancer where we were hit by 50% performance regression.

When tasks are assigned to a subset of CPUs that span across
sched_domains (either ccNUMA node or the new multi-core domain) via
cpu affinity, kernel fails to perform proper load balance at
these domains, due to several logic in find_busiest_group() miss
identified busiest sched group within a given domain. This leads to
inadequate load balance and causes 50% performance hit.

To give you a concrete example, on a dual-core, 2 socket numa system,
there are 4 logical cpu, organized as:

CPU0 attaching sched-domain:
 domain 0: span 0003  groups: 0001 0002
 domain 1: span 000f  groups: 0003 000c
CPU1 attaching sched-domain:
 domain 0: span 0003  groups: 0002 0001
 domain 1: span 000f  groups: 0003 000c
CPU2 attaching sched-domain:
 domain 0: span 000c  groups: 0004 0008
 domain 1: span 000f  groups: 000c 0003
CPU3 attaching sched-domain:
 domain 0: span 000c  groups: 0008 0004
 domain 1: span 000f  groups: 000c 0003

If I run 2 tasks with CPU affinity set to 0x5.  There are situation
where cpu0 has run queue length of 2, and cpu2 will be idle.  The
kernel load balancer is unable to balance out these two tasks over
cpu0 and cpu2 due to at least three logics in find_busiest_group()
that heavily bias load balance towards power saving mode. e.g. while
determining "busiest" variable, kernel only set it when
"sum_nr_running > group_capacity".  This test is flawed that
"sum_nr_running" is not necessary same as
sum-tasks-allowed-to-run-within-the sched-group.  The end result is
that kernel "think" everything is balanced, but in reality we have an
imbalance and thus causing one CPU to be over-subscribed and leaving
other idle.  There are two other logic in the same function will also
causing similar effect.  The nastiness of this bug is that kernel not
be able to get unstuck in this unfortunate broken state.  From what
we've seen in our environment, kernel will stuck in imbalanced state
for extended period of time and it is also very easy for the kernel to
stuck into that state (it's pretty much 100% reproducible for us).

So proposing the following fix: add addition logic in
find_busiest_group to detect intrinsic imbalance within the busiest
group.  When such condition is detected, load balance goes into spread
mode instead of default grouping mode.

Signed-off-by: Ken Chen <kenchen@google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-17 16:55:11 +02:00
Milton Miller cd79007634 sched: more robust sd-sysctl entry freeing
It occurred to me this morning that the procname field was dynamically
allocated and needed to be freed.  I started to put in break statements
when allocation failed but it was approaching 50% error handling code.

I came up with this alternative of looping while entry->mode is set and
checking proc_handler instead of ->table.  Alternatively, the string
version of the domain name and cpu number could be stored the structs.

I verified by compiling CONFIG_DEBUG_SLAB and checking the allocation
counts after taking a cpuset exclusive and back.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-17 16:55:11 +02:00
Paul Jackson 607717a65d cpuset: remove sched domain hooks from cpusets
Remove the cpuset hooks that defined sched domains depending on the setting
of the 'cpu_exclusive' flag.

The cpu_exclusive flag can only be set on a child if it is set on the
parent.

This made that flag painfully unsuitable for use as a flag defining a
partitioning of a system.

It was entirely unobvious to a cpuset user what partitioning of sched
domains they would be causing when they set that one cpu_exclusive bit on
one cpuset, because it depended on what CPUs were in the remainder of that
cpusets siblings and child cpusets, after subtracting out other
cpu_exclusive cpusets.

Furthermore, there was no way on production systems to query the
result.

Using the cpu_exclusive flag for this was simply wrong from the get go.

Fortunately, it was sufficiently borked that so far as I know, almost no
successful use has been made of this.  One real time group did use it to
affectively isolate CPUs from any load balancing efforts.  They are willing
to adapt to alternative mechanisms for this, such as someway to manipulate
the list of isolated CPUs on a running system.  They can do without this
present cpu_exclusive based mechanism while we develop an alternative.

There is a real risk, to the best of my understanding, of users
accidentally setting up a partitioned scheduler domains, inhibiting desired
load balancing across all their CPUs, due to the nonobvious (from the
cpuset perspective) side affects of the cpu_exclusive flag.

Furthermore, since there was no way on a running system to see what one was
doing with sched domains, this change will be invisible to any using code.
Unless they have real insight to the scheduler load balancing choices, they
will be unable to detect that this change has been made in the kernel's
behaviour.

Initial discussion on lkml of this patch has generated much comment.  My
(probably controversial) take on that discussion is that it has reached a
rough concensus that the current cpuset cpu_exclusive mechanism for
defining sched domains is borked.  There is no concensus on the
replacement.  But since we can remove this mechanism, and since its
continued presence risks causing unwanted partitioning of the schedulers
load balancing, we should remove it while we can, as we proceed to work the
replacement scheduler domain mechanisms.

Signed-off-by: Paul Jackson <pj@sgi.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Christoph Lameter <clameter@engr.sgi.com>
Cc: Dinakar Guniguntala <dino@in.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-16 09:43:09 -07:00
Mike Travis d5a7430ddc Convert cpu_sibling_map to be a per cpu variable
Convert cpu_sibling_map from a static array sized by NR_CPUS to a per_cpu
variable.  This saves sizeof(cpumask_t) * NR unused cpus.  Access is mostly
from startup and CPU HOTPLUG functions.

Signed-off-by: Mike Travis <travis@sgi.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: "Siddha, Suresh B" <suresh.b.siddha@intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: "Luck, Tony" <tony.luck@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-16 09:42:50 -07:00
Ingo Molnar 9c63d9c021 sched: sync wakeups preempt too
make sure sync wakeups preempt too - the scheduler will not
overschedule as we've got various throttles against that.
As a result, sync wakeups can be used more widely in the kernel
(to signal wakeup affinity between tasks), and no arbitrary
latencies will be introduced either.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15 17:00:20 +02:00
Ingo Molnar 71e20f1873 sched: affine sync wakeups
make sync wakeups affine for cache-cold tasks: if a cache-cold task
is woken up by a sync wakeup then use the opportunity to migrate it
straight away. (the two tasks are 'related' because they communicate)

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15 17:00:19 +02:00
Laurent Vivier 94886b84b1 sched: guest CPU accounting: maintain stats in account_system_time()
modify account_system_time() to add cputime to cpustat->guest if we are
running a VCPU. We add this cputime to cpustat->user instead of
cpustat->system because this part of KVM code is in fact user code
although it is executed in the kernel. We duplicate VCPU time between
guest and user to allow an unmodified "top(1)" to display correct value.
A modified "top(1)" is able to display good cpu user time and cpu guest
time by subtracting cpu guest time from cpu user time. Update "gtime" in
task_struct accordingly.

Signed-off-by: Laurent Vivier <Laurent.Vivier@bull.net>
Acked-by: Avi Kivity <avi@qumranet.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15 17:00:19 +02:00
Milton Miller 6323469f9b sched: domain sysctl fixes: add terminator comment
we had an incorrect-terminator bug in sd_alloc_ctl_domain_table()
before, so add a comment that documents it.

Signed-off-by: Milton Miller <miltonm@bga.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15 17:00:19 +02:00
Milton Miller ad1cdc1d78 sched: domain sysctl fixes: do not crash on allocation failure
Now that we are calling this at runtime, a more relaxed error path is
suggested.  If an allocation fails, we just register the partial table,
which will show empty directories.

Signed-off-by: Milton Miller <miltonm@bga.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15 17:00:19 +02:00
Milton Miller 6382bc90f5 sched: domain sysctl fixes: unregister the sysctl table before domains
Unregister and free the sysctl table before destroying domains, then
rebuild and register after creating the new domains.  This prevents the
sysctl table from pointing to freed memory for root to write.

Signed-off-by: Milton Miller <miltonm@bga.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15 17:00:19 +02:00
Milton Miller 97b6ea7b63 sched: domain sysctl fixes: use for_each_online_cpu()
init_sched_domain_sysctl was walking cpus 0-n and referencing per_cpu
variables.  If the cpus_possible mask is not contigious this will result
in a crash referencing unallocated data.  If the online mask is not
contigious then we would show offline cpus and miss online ones.

Signed-off-by: Milton Miller <miltonm@bga.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15 17:00:19 +02:00
Milton Miller 5cf9f062c8 sched: domain sysctl fixes: use kcalloc()
kcalloc checks for n * sizeof(element) overflows and it zeros.

Signed-off-by: Milton Miller <miltonm@bga.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15 17:00:19 +02:00
Ingo Molnar 6bc1665ba7 sched: allow the immediate migration of cache-cold tasks
allow the immediate migration of cache-cold tasks.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15 17:00:18 +02:00
Ingo Molnar cc367732ff sched: debug, improve migration statistics
add new migration statistics when SCHED_DEBUG and SCHEDSTATS
is enabled. Available in /proc/<PID>/sched.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15 17:00:18 +02:00
Peter Zijlstra ff56b2f015 sched: activate task_hot() only on fair-scheduled tasks
activate task_hot() only for fair-scheduled tasks (i.e. disable it
for RT tasks).

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15 17:00:18 +02:00
Ingo Molnar da84d96176 sched: reintroduce cache-hot affinity
reintroduce a simplified version of cache-hot/cold scheduling
affinity. This improves performance with certain SMP workloads,
such as sysbench.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15 17:00:18 +02:00
Ingo Molnar 178be79348 sched: do not normalize kernel threads via SysRq-N
do not normalize kernel threads via SysRq-N: the migration threads,
softlockup threads, etc. might be essential for the system to
function properly. So only zap user tasks.

pointed out by Andi Kleen.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15 17:00:18 +02:00
Andi Kleen 1666703af9 sched: remove stale comment from sched_group_set_shares()
remove stale comment from sched_group_set_shares().

Function never returns -EINVAL.

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15 17:00:18 +02:00
Ingo Molnar d5036e89dc sched: clean up is_migration_thread()
clean up is_migration_thread() and turn it into an inline function.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15 17:00:15 +02:00
Andi Kleen 3a5e4dc12f sched: cleanup: refactor normalize_rt_tasks
Replace a particularly ugly ifdef with an inline and a new macro.
Also split up the function to be easier to read.

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15 17:00:15 +02:00
Andi Kleen 8cbbe86dfc sched: cleanup: refactor common code of sleep_on / wait_for_completion
Refactor common code of sleep_on / wait_for_completion

These functions were largely cut'n'pasted. This moves
the common code into single helpers instead.  Advantage
is about 1k less code on x86-64 and 91 lines of code removed.
It adds one function call to the non timeout version of
the functions; i don't expect this to be measurable.

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15 17:00:14 +02:00
Andi Kleen 3a5c359a58 sched: cleanup: remove unnecessary gotos
Replace loops implemented with gotos with real loops.
Replace err = ...; goto x; x: return err; with return ...;

No functional changes.

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15 17:00:14 +02:00
Mike Galbraith 95938a35c5 sched: prevent wakeup over-scheduling
Prevent wakeup over-scheduling.  Once a task has been preempted by a
task of the same or lower priority, it becomes ineligible for repeated
preemption by same until it has been ticked, or slept.  Instead, the
task is marked for preemption at the next tick.  Tasks of higher
priority still preempt immediately.

Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15 17:00:14 +02:00
Peter Zijlstra ce6c131131 sched: disable forced preemption by default
Implement feature bit to disable forced preemption. This way
it can be checked whether a workload is overscheduling or not.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15 17:00:14 +02:00
Zou Nan hai ace8b3d633 sched: some proc entries are missed in sched_domain sys_ctl debug code
cache_nice_tries and flags entry do not appear in proc fs sched_domain
directory, because ctl_table entry is skipped.

This patch fixes the issue.

Signed-off-by: Zou Nan hai <nanhai.zou@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15 17:00:14 +02:00
Gautham R Shenoy 638e13ac37 sched: fix rt ptracer monopolizing CPU
yield() in wait_task_inactive(), can cause a high priority thread to be
scheduled back in, and there by loop forever while it is waiting for some
lower priority thread which is unfortunately still on the runqueue.

Use schedule_timeout_uninterruptible(1) instead.

Signed-off-by: Gautham R Shenoy <ego@in.ibm.com>
Credit: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15 17:00:14 +02:00
Dhaval Giani 5cb350baf5 sched: group scheduling, sysfs tunables
Add tunables in sysfs to modify a user's cpu share.

A directory is created in sysfs for each new user in the system.

	/sys/kernel/uids/<uid>/cpu_share

Reading this file returns the cpu shares granted for the user.
Writing into this file modifies the cpu share for the user. Only an
administrator is allowed to modify a user's cpu share.

Ex:
	# cd /sys/kernel/uids/
	# cat 512/cpu_share
	1024
	# echo 2048 > 512/cpu_share
	# cat 512/cpu_share
	2048
	#

Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: Dhaval Giani <dhaval@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15 17:00:14 +02:00
Paul E. McKenney a58f6f253d sched: export cpu_clock()
export cpu_clock() - the preferred API instead of sched_clock().

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15 17:00:14 +02:00
Ingo Molnar 00bf7bfc2e sched: fix: move the CPU check into ->task_new_fair()
noticed by Peter Zijlstra:

fix: move the CPU check into ->task_new_fair(), this way we
can call place_entity() and get child ->vruntime right at
initial wakeup time.

(without this there can be large latencies)

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
2007-10-15 17:00:14 +02:00
Ingo Molnar 4cf86d77f5 sched: cleanup: rename task_grp to task_group
cleanup: rename task_grp to task_group. No need to save two characters
and 'grp' is annoying to read.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15 17:00:14 +02:00
Ingo Molnar 06877c33fe sched: cleanup: rename SCHED_FEAT_USE_TREE_AVG to SCHED_FEAT_TREE_AVG
cleanup: rename SCHED_FEAT_USE_TREE_AVG to SCHED_FEAT_TREE_AVG, to
make SCHED_FEAT_ names more consistent.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15 17:00:13 +02:00
Ingo Molnar a65914b365 sched: kfree(NULL) is valid
kfree(NULL) is valid.

pointed out by checkpatch.pl.

the fix shrinks the code a bit:

   text    data     bss     dec     hex filename
  40024    3842     100   43966    abbe sched.o.before
  40002    3842     100   43944    aba8 sched.o.after

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15 17:00:13 +02:00
Ingo Molnar 8927f49479 sched: style cleanup
fix up __setup() style bug - noticed via checkpatch.pl.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15 17:00:13 +02:00
Ingo Molnar 26797a34a2 sched: break out if printing a warning in sched_domain_debug()
checkpatch.pl and Andy Whitcroft noticed the following bug: we did
not break out after printing an error.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15 17:00:13 +02:00
Ingo Molnar 3e9830dcab sched: run sched_domain_debug() if CONFIG_SCHED_DEBUG=y
run sched_domain_debug() if CONFIG_SCHED_DEBUG=y, instead
of relying on the hand-crafted SCHED_DOMAIN_DEBUG switch.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15 17:00:13 +02:00
Dmitry Adamushko a4ec24b48d sched: tidy up SCHED_RR
- make timeslices of SCHED_RR tasks constant and not
dependent on task's static_prio [1] ;
- remove obsolete code (timeslice related bits);
- make sched_rr_get_interval() return something more
meaningful [2] for SCHED_OTHER tasks.

[1] according to the following link, it's not compliant with SUSv3
(not sure though, what is the reference for us :-)
http://lkml.org/lkml/2007/3/7/656

[2] the interval is dynamic and can be depicted as follows "should a
task be one of the runnable tasks at this particular moment, it would
expect to run for this interval of time before being re-scheduled by the
scheduler tick".
(i.e. it's more precise if a task is runnable at the moment)

yeah, this seems to require task_rq_lock/unlock() but this is not a hot
path.

results:

(SCHED_FIFO)

dimm@earth:~/storage/prog$ sudo chrt -f 10 ./rr_interval 
time_slice: 0 : 0

(SCHED_RR)

dimm@earth:~/storage/prog$ sudo chrt 10 ./rr_interval 
time_slice: 0 : 99984800

(SCHED_NORMAL)

dimm@earth:~/storage/prog$ ./rr_interval 
time_slice: 0 : 19996960

(SCHED_NORMAL + a cpu_hog of similar 'weight' on the same CPU --- so should be a half of the previous result)

dimm@earth:~/storage/prog$ taskset 1 ./rr_interval 
time_slice: 0 : 9998480

Signed-off-by: Dmitry Adamushko <dmitry.adamushko@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15 17:00:13 +02:00
Alexey Dobriyan a9957449b0 sched: uninline scheduler
* save ~300 bytes
* activate_idle_task() was moved to avoid a warning

bloat-o-meter output:

add/remove: 6/0 grow/shrink: 0/16 up/down: 438/-733 (-295)		<===
function                                     old     new   delta
__enqueue_entity                               -     165    +165
finish_task_switch                             -     110    +110
update_curr_rt                                 -      79     +79
__load_balance_iterator                        -      32     +32
__task_rq_unlock                               -      28     +28
find_process_by_pid                            -      24     +24
do_sched_setscheduler                        133     123     -10
sys_sched_rr_get_interval                    176     165     -11
sys_sched_getparam                           156     145     -11
normalize_rt_tasks                           482     470     -12
sched_getaffinity                            112      99     -13
sys_sched_getscheduler                        86      72     -14
sched_setaffinity                            226     212     -14
sched_setscheduler                           666     642     -24
load_balance_start_fair                       33       9     -24
load_balance_next_fair                        33       9     -24
dequeue_task_rt                              133      67     -66
put_prev_task_rt                              97      28     -69
schedule_tail                                133      50     -83
schedule                                     682     594     -88
enqueue_entity                               499     366    -133
task_new_fair                                317     180    -137

Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15 17:00:13 +02:00
Ingo Molnar 1e81995066 sched: optimize schedule() a bit on SMP
optimize schedule() a bit on SMP, by moving the rq-clock update
outside the rq lock.

code size is the same:

      text    data     bss     dec     hex filename
     25725    2666      96   28487    6f47 sched.o.before
     25725    2666      96   28487    6f47 sched.o.after

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:13 +02:00
Ingo Molnar 3a25201572 sched: whitespace cleanups
more whitespace cleanups. No code changed:

      text    data     bss     dec     hex filename
     26553    2790     288   29631    73bf sched.o.before
     26553    2790     288   29631    73bf sched.o.after

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:12 +02:00
Ingo Molnar 5522d5d5f7 sched: mark scheduling classes as const
mark scheduling classes as const. The speeds up the code
a bit and shrinks it:

   text    data     bss     dec     hex filename
  40027    4018     292   44337    ad31 sched.o.before
  40190    3842     292   44324    ad24 sched.o.after

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:12 +02:00
Srivatsa Vaddagiri 2830cf8c90 sched: group scheduler SMP migration fix
group scheduler SMP migration fix: use task_cfs_rq(p) to get
to the relevant fair-scheduling runqueue of a task, rq->cfs
is not the right one.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15 17:00:12 +02:00
Ingo Molnar 2d72376b3a sched: clean up schedstats, cnt -> count
rename all 'cnt' fields and variables to the less yucky 'count' name.

yuckage noticed by Andrew Morton.

no change in code, other than the /proc/sched_debug bkl_count string got
a bit larger:

   text    data     bss     dec     hex filename
  38236    3506      24   41766    a326 sched.o.before
  38240    3506      24   41770    a32a sched.o.after

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:12 +02:00
Hiroshi Shimamoto 2ddbf95250 sched: clean up sched_fork()
The adjusting sched_class is a missing part of the already existing "do
not leak PI boosting priority to the child" at the sched_fork(). This
patch moves the adjusting sched_class from wake_up_new_task() to
sched_fork().

this also shrinks the code a bit:

   text    data     bss     dec     hex filename
  40111    4018     292   44421    ad85 sched.o.before
  40102    4018     292   44412    ad7c sched.o.after

Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Signed-off-by: Dmitry Adamushko <dmitry.adamushko@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:11 +02:00
Ingo Molnar 02e4bac2a5 sched: fix sched_fork()
fix sched_fork(): large latencies at new task creation time because
the ->vruntime was not fixed up cross-CPU, if the parent got migrated
after the child's CPU got set up.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:11 +02:00
Ingo Molnar 94359f05cb sched: undo some of the recent changes
undo some of the recent changes that are not needed after all,
such as last_min_vruntime.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
2007-10-15 17:00:11 +02:00
Ingo Molnar 785c29ef95 sched: remove condition from set_task_cpu()
remove condition from set_task_cpu(). Now that ->vruntime
is not global anymore, it should (and does) work fine without
it too.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
2007-10-15 17:00:11 +02:00
Peter Zijlstra ddc9729750 sched debug: check spread
debug feature: check how well we schedule within a reasonable
vruntime 'spread' range. (note that CPU overload can increase
the spread, so this is not a hard condition, but normal loads
should be within the spread.)

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
2007-10-15 17:00:10 +02:00
Peter Zijlstra 67e9fb2a39 sched: add vslice
add vslice: the load-dependent "virtual slice" a task should
run ideally, so that the observed latency stays within the
sched_latency window.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:10 +02:00
Ingo Molnar b8efb56172 sched debug: BKL usage statistics
add per task and per rq BKL usage statistics.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:10 +02:00
Srivatsa Vaddagiri 24e377a832 sched: add fair-user scheduler
Enable user-id based fair group scheduling. This is useful for anyone
who wants to test the group scheduler w/o having to enable
CONFIG_CGROUPS.

A separate scheduling group (i.e struct task_grp) is automatically created for 
every new user added to the system. Upon uid change for a task, it is made to 
move to the corresponding scheduling group.

A /proc tunable (/proc/root_user_share) is also provided to tune root
user's quota of cpu bandwidth.

Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: Dhaval Giani <dhaval@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:09 +02:00
Srivatsa Vaddagiri 9b5b77512d sched: clean up code under CONFIG_FAIR_GROUP_SCHED
With the view of supporting user-id based fair scheduling (and not just
container-based fair scheduling), this patch renames several functions
and makes them independent of whether they are being used for container
or user-id based fair scheduling.

Also fix a problem reported by KAMEZAWA Hiroyuki (wrt allocating
less-sized array for tg->cfs_rq[] and tf->se[]).

Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: Dhaval Giani <dhaval@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:09 +02:00
Srivatsa Vaddagiri 83b699ed20 sched: revert recent removal of set_curr_task()
Revert removal of set_curr_task.
Use put_prev_task/set_curr_task when changing groups/policies

Signed-off-by: Srivatsa Vaddagiri < vatsa@linux.vnet.ibm.com>
Signed-off-by: Dhaval Giani <dhaval@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
2007-10-15 17:00:08 +02:00
Dmitry Adamushko f6b53205e1 sched: rework enqueue/dequeue_entity() to get rid of set_curr_task()
rework enqueue/dequeue_entity() to get rid of 
sched_class::set_curr_task(). This simplifies sched_setscheduler(), 
rt_mutex_setprio() and sched_move_tasks().

   text    data     bss     dec     hex filename
  24330    2734      20   27084    69cc sched.o.before
  24233    2730      20   26983    6967 sched.o.after

Signed-off-by: Dmitry Adamushko <dmitry.adamushko@gmail.com>
Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:08 +02:00
Dmitry Adamushko 4530d7ab0f sched: simplify sched_class::yield_task()
the 'p' (task_struct) parameter in the sched_class :: yield_task() is
redundant as the caller is always the 'current'. Get rid of it.

   text    data     bss     dec     hex filename
  24341    2734      20   27095    69d7 sched.o.before
  24330    2734      20   27084    69cc sched.o.after

Signed-off-by: Dmitry Adamushko <dmitry.adamushko@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:08 +02:00
Dmitry Adamushko 30cfdcfc5f sched: do not keep current in the tree and get rid of sched_entity::fair_key
Get rid of 'sched_entity::fair_key'.

As a side effect, 'current' is not kept withing the tree for 
SCHED_NORMAL/BATCH tasks anymore. This simplifies some parts of code 
(e.g. entity_tick() and yield_task_fair()) and also somewhat optimizes 
them (e.g. a single update_curr() now vs. dequeue/enqueue() before in 
entity_tick()).

Signed-off-by: Dmitry Adamushko <dmitry.adamushko@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:07 +02:00
Dmitry Adamushko 7074badbcb sched: add set_curr_task() calls
p->sched_class->set_curr_task() has to be called before 
activate_task()/enqueue_task() in rt_mutex_setprio(), 
sched_setschedule() and sched_move_task() in order to set up 
'cfs_rq->curr'. The logic of enqueueing depends on whether a task to be 
inserted is 'current' or not.

Signed-off-by: Dmitry Adamushko <dmitry.adamushko@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:07 +02:00
Srivatsa Vaddagiri 29f59db3a7 sched: group-scheduler core
Add interface to control cpu bandwidth allocation to task-groups.

(not yet configurable, due to missing CONFIG_CONTAINERS)

Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: Dhaval Giani <dhaval@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
2007-10-15 17:00:07 +02:00
Mike Galbraith 119fe5e068 sched: fix SMP migration latencies
fix SMP migration latencies: the vruntimes of different CPUs are
at incompatible offsets so they have to be fixed up when migrating
a task across CPUs.

Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:07 +02:00
Ingo Molnar bbdba7c0e1 sched: remove wait_runtime fields and features
remove wait_runtime based fields and features, now that the CFS
math has been changed over to the vruntime metric.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:06 +02:00
Ingo Molnar e22f5bbf86 sched: remove wait_runtime limit
remove the wait_runtime-limit fields and the code depending on it, now
that the math has been changed over to rely on the vruntime metric.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:06 +02:00
Dmitry Adamushko 495eca494a sched: clean up struct load_stat
'struct load_stat' is redundant now so let's get rid of it.

Signed-off-by: Dmitry Adamushko <dmitry.adamushko@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:06 +02:00
Peter Zijlstra 94dfb5e75e sched: add tree based averages
add support for tree based vruntime averages.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:05 +02:00
Ingo Molnar 28a1f6fa2f sched: remove SCHED_FEAT_SKIP_INITIAL
remove SCHED_FEAT_SKIP_INITIAL - it was off by default and even
when enabled it never made any real difference.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:05 +02:00
Ingo Molnar 6cb5819514 sched: optimize vruntime based scheduling
optimize vruntime based scheduling.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:04 +02:00
Ingo Molnar bf5c91ba8c sched: move sched_feat() definitions
move sched_feat() definitions so that it can be used sooner by generic
code too.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:04 +02:00
Ingo Molnar e9acbff648 sched: introduce se->vruntime
introduce se->vruntime as a sum of weighted delta-exec's, and use that
as the key into the tree.

the idea to use absolute virtual time as the basic metric of scheduling
has been first raised by William Lee Irwin, advanced by Tong Li and first
prototyped by Roman Zippel in the "Really Fair Scheduler" (RFS) patchset.

also see:

   http://lkml.org/lkml/2007/9/2/76

for a simpler variant of this patch.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:04 +02:00
Ingo Molnar 1091985b48 sched: speed up update_load_add/_sub()
speed up update_load_add/_sub() by not delaying the division - this
reduces CPU pipeline dependencies.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:04 +02:00
Ingo Molnar 62160e3f4a sched: track cfs_rq->curr on !group-scheduling too
Noticed by Roman Zippel: use cfs_rq->curr in the !group-scheduling
case too. Small micro-optimization and cleanup effect:

   text    data     bss     dec     hex filename
   36269    3482      24   39775    9b5f sched.o.before
   36177    3486      24   39687    9b07 sched.o.after

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:03 +02:00
Ingo Molnar 53df556e06 sched: remove precise CPU load calculations #2
continued removal of precise CPU load calculations.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:03 +02:00
Ingo Molnar a25707f3ae sched: remove precise CPU load
CPU load calculations are statistical anyway, and there's little benefit
from having it calculated on every scheduling event. So remove this code,
it gets rid of a divide from the scheduler wakeup and context-switch
fastpath.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:03 +02:00
Ingo Molnar 8ebc91d936 sched: remove stat_gran
remove the stat_gran code - it was disabled by default and it causes
unnecessary overhead.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:03 +02:00
Ingo Molnar 2bd8e6d422 sched: use constants if !CONFIG_SCHED_DEBUG
use constants if !CONFIG_SCHED_DEBUG.

this speeds up the code and reduces code-size:

    text    data     bss     dec     hex filename
   27464    3014      16   30494    771e sched.o.before
   26929    3010      20   29959    7507 sched.o.after

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:02 +02:00
Ingo Molnar 38ad464d41 sched: uniform tunings
use the same defaults on both UP and SMP.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:02 +02:00
Ingo Molnar eba1ed4b7e sched: debug: track maximum 'slice'
track the maximum amount of time a task has executed while
the CPU load was at least 2x. (i.e. at least two nice-0
tasks were runnable)

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:02 +02:00
Matthias Kaehlcke 2e45874c5a sched: use list_for_each_entry_safe() in __wake_up_common()
Use list_for_each_entry_safe() instead of list_for_each_safe() in
__wake_up_common()

Signed-off-by: Matthias Kaehlcke <matthias.kaehlcke@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:02 +02:00
Ingo Molnar 44142fac34 sched: fix sysctl_sched_child_runs_first flag
fix the sched_child_runs_first flag: always call into ->task_new()
if we are on the same CPU, as SCHED_OTHER tasks depend on it for
correct initial setup.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15 17:00:01 +02:00
Jens Axboe f5ff8422bb Fix warnings with !CONFIG_BLOCK
Hide everything in blkdev.h with CONFIG_BLOCK isn't set, and fixup
the (few) files that fail to build because they were relying on blkdev.h
pulling in extra includes for them.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-10-10 09:25:57 +02:00
Hiroshi Shimamoto 9c95e7319b sched: fix invalid sched_class use
When using rt_mutex, a NULL pointer dereference is occurred at
enqueue_task_rt. Here is a scenario;
1) there are two threads, the thread A is fair_sched_class and
   thread B is rt_sched_class.
2) Thread A is boosted up to rt_sched_class, because the thread A
   has a rt_mutex lock and the thread B is waiting the lock.
3) At this time, when thread A create a new thread C, the thread
   C has a rt_sched_class.
4) When doing wake_up_new_task() for the thread C, the priority
   of the thread C is out of the RT priority range, because the
   normal priority of thread A is not the RT priority. It makes
   data corruption by overflowing the rt_prio_array.
The new thread C should be fair_sched_class.

The new thread should be valid scheduler class before queuing.
This patch fixes to set the suitable scheduler class.

Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
2007-09-19 23:34:46 +02:00
Ingo Molnar 1799e35d5b sched: add /proc/sys/kernel/sched_compat_yield
add /proc/sys/kernel/sched_compat_yield to make sys_sched_yield()
more agressive, by moving the yielding task to the last position
in the rbtree.

with sched_compat_yield=0:

   PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
  2539 mingo     20   0  1576  252  204 R   50  0.0   0:02.03 loop_yield
  2541 mingo     20   0  1576  244  196 R   50  0.0   0:02.05 loop

with sched_compat_yield=1:

   PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
  2584 mingo     20   0  1576  248  196 R   99  0.0   0:52.45 loop
  2582 mingo     20   0  1576  256  204 R    0  0.0   0:00.00 loop_yield

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
2007-09-19 23:34:46 +02:00
Ingo Molnar cf2ab4696e sched: fix xtensa build warning
rename RSR to SRR - 'RSR' is already defined on xtensa.

found by Adrian Bunk.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-09-05 14:32:49 +02:00
Ingo Molnar a206c07213 sched: debug: fix cfs_rq->wait_runtime accounting
the cfs_rq->wait_runtime debug/statistics counter was not maintained
properly - fix this.

this also removes some code:

   text    data     bss     dec     hex filename
  13420     228    1204   14852    3a04 sched.o.before
  13404     228    1204   14836    39f4 sched.o.after

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
2007-09-05 14:32:49 +02:00
Suresh Siddha 7fd0d2dde9 sched: fix MC/HT scheduler optimization, without breaking the FUZZ logic.
First fix the check
	if (*imbalance + SCHED_LOAD_SCALE_FUZZ < busiest_load_per_task)
with this
	if (*imbalance < busiest_load_per_task)

As the current check is always false for nice 0 tasks (as
SCHED_LOAD_SCALE_FUZZ is same as busiest_load_per_task for nice 0
tasks).

With the above change, imbalance was getting reset to 0 in the corner
case condition, making the FUZZ logic fail. Fix it by not corrupting the
imbalance and change the imbalance, only when it finds that the HT/MC
optimization is needed.

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-09-05 14:32:48 +02:00
Ingo Molnar f6cf891c4d sched: make the scheduler converge to the ideal latency
de-HZ-ification of the granularity defaults unearthed a pre-existing
property of CFS: while it correctly converges to the granularity goal,
it does not prevent run-time fluctuations in the range of
[-gran ... 0 ... +gran].

With the increase of the granularity due to the removal of HZ
dependencies, this becomes visible in chew-max output (with 5 tasks
running):

 out:  28 . 27. 32 | flu:  0 .  0 | ran:    9 .   13 | per:   37 .   40
 out:  27 . 27. 32 | flu:  0 .  0 | ran:   17 .   13 | per:   44 .   40
 out:  27 . 27. 32 | flu:  0 .  0 | ran:    9 .   13 | per:   36 .   40
 out:  29 . 27. 32 | flu:  2 .  0 | ran:   17 .   13 | per:   46 .   40
 out:  28 . 27. 32 | flu:  0 .  0 | ran:    9 .   13 | per:   37 .   40
 out:  29 . 27. 32 | flu:  0 .  0 | ran:   18 .   13 | per:   47 .   40
 out:  28 . 27. 32 | flu:  0 .  0 | ran:    9 .   13 | per:   37 .   40

average slice is the ideal 13 msecs and the period is picture-perfect 40
msecs. But the 'ran' field fluctuates around 13.33 msecs and there's no
mechanism in CFS to keep that from happening: it's a perfectly valid
solution that CFS finds.

to fix this we add a granularity/preemption rule that knows about
the "target latency", which makes tasks that run longer than the ideal
latency run a bit less. The simplest approach is to simply decrease the
preemption granularity when a task overruns its ideal latency. For this
we have to track how much the task executed since its last preemption.

( this adds a new field to task_struct, but we can eliminate that
  overhead in 2.6.24 by putting all the scheduler timestamps into an
  anonymous union. )

with this change in place, chew-max output is fluctuation-less all
around:

 out:  28 . 27. 39 | flu:  0 .  2 | ran:   13 .   13 | per:   41 .   40
 out:  28 . 27. 39 | flu:  0 .  2 | ran:   13 .   13 | per:   41 .   40
 out:  28 . 27. 39 | flu:  0 .  2 | ran:   13 .   13 | per:   41 .   40
 out:  28 . 27. 39 | flu:  0 .  2 | ran:   13 .   13 | per:   41 .   40
 out:  28 . 27. 39 | flu:  0 .  1 | ran:   13 .   13 | per:   41 .   40
 out:  28 . 27. 39 | flu:  0 .  1 | ran:   13 .   13 | per:   41 .   40

this patch has no impact on any fastpath or on any globally observable
scheduling property. (unless you have sharp enough eyes to see
millisecond-level ruckles in glxgears smoothness :-)

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mike Galbraith <efault@gmx.de>
2007-08-28 12:53:24 +02:00
Ingo Molnar 50c46637aa sched: s/sched_latency/sched_min_granularity
runtime limit and wakeup granularity used to be a function of
granularity and that was incorrect changed to sched_latency.

Fix this to make wakeup granularity a function of min-granularity,
and the runtime limit equal to latency.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-25 22:17:19 +02:00
Ingo Molnar 172ac3dbb7 sched: cleanup, sched_granularity -> sched_min_granularity
due to adaptive granularity scheduling the role of sched_granularity
has changed to "minimum granularity", so rename the variable (and the
tunable) accordingly.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
2007-08-25 18:41:53 +02:00
Peter Zijlstra 218050855e sched: adaptive scheduler granularity
Instead of specifying the preemption granularity, specify the wanted
latency. By fixing the granlarity to a constany the wakeup latency
it a function of the number of running tasks on the rq.

Invert this relation.

sysctl_sched_granularity becomes a minimum for the dynamic granularity
computed from the new sysctl_sched_latency.

Then use this latency to do more intelligent granularity decisions: if
there are fewer tasks running then we can schedule coarser. This helps
performance while still always keeping the latency target.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-25 18:41:53 +02:00
Sven-Thorsten Dietrich deac4ee65a sched: simplify can_migrate_task()
Remove trivial conditional branch in Linux scheduler's
can_migrate_task() function.

   text    data     bss     dec     hex filename
   34770    2998      24   37792    93a0 sched.o.before
   34757    2998      24   37779    9393 sched.o.after

Signed-off-by: Sven-Thorsten Dietrich <sven@thebigcorporation.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-24 20:39:10 +02:00
Ingo Molnar 71fd371463 sched: remove HZ dependency from the granularity default
remove HZ dependency from the granularity default. Use 10 msec for
the base granularity, 1 msec for wakeup granularity and 25 msec for
batch wakeup granularity. (These defaults are close to the values
that the default HZ=250 setting got previously, and thus it's the
most common setting.)

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-24 20:39:10 +02:00
Ingo Molnar 505c0efd58 sched: tweak the sched_runtime_limit tunable
Michael Gerdau reported reniced task CPU usage weirdnesses.
Such symptoms can be caused by limit underruns so double the
sched_runtime_limit.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-23 15:18:02 +02:00
Suresh Siddha f549da848e sched: skip updating rq's next_balance under null SD
Was playing with sched_smt_power_savings/sched_mc_power_savings and
found out that while the scheduler domains are reconstructed when sysfs
settings change, rebalance_domains() can get triggered with null domain
on other cpus, which is setting next_balance to jiffies + 60*HZ.
Resulting in no idle/busy balancing for 60 seconds.

Fix this.

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-23 15:18:02 +02:00
Suresh Siddha f8700df7c4 sched: fix broken SMT/MC optimizations
On a four package system with HT - HT load balancing optimizations were
broken.  For example, if two tasks end up running on two logical threads
of one of the packages, scheduler is not able to pull one of the tasks
to a completely idle package.

In this scenario, for nice-0 tasks, imbalance calculated by scheduler
will be 512 and find_busiest_queue() will return 0 (as each cpu's load
is 1024 > imbalance and has only one task running).

Similarly MC scheduler optimizations also get fixed with this patch.

[ mingo@elte.hu: restored fair balancing by increasing the fuzz and
                 adding it back to the power decision, without the /2
                 factor. ]

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-23 15:18:02 +02:00
Eric W. Biederman c57baf1e1e sched: fix sysctl directory permissions
There are two remaining gotchas:

- The directories have impossible permissions (writeable).

- The ctl_name for the kernel directory is inconsistent with
  everything else.  It should be CTL_KERN.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-23 15:18:02 +02:00
Ingo Molnar 2aa44d0567 sched: sched_clock_idle_[sleep|wakeup]_event()
construct a more or less wall-clock time out of sched_clock(), by
using ACPI-idle's existing knowledge about how much time we spent
idling. This allows the rq clock to work around TSC-stops-in-C2,
TSC-gets-corrupted-in-C3 type of problems.

( Besides the scheduler's statistics this also benefits blktrace and
  printk-timestamps as well. )

Furthermore, the precise before-C2/C3-sleep and after-C2/C3-wakeup
callbacks allow the scheduler to get out the most of the period where
the CPU has a reliable TSC. This results in slightly more precise
task statistics.

the ACPI bits were acked by Len.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Len Brown <len.brown@intel.com>
2007-08-23 15:18:02 +02:00
Oleg Nesterov de0cf899bb sched: run_rebalance_domains: s/SCHED_IDLE/CPU_IDLE/
rebalance_domains(SCHED_IDLE) looks strange (typo), change it to CPU_IDLE.

the effect of this bug was slightly more agressive idle-balancing on
SMP than intended.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-12 18:08:19 +02:00
Adrian Bunk 6707de00fd sched: make global code static
This patch makes the following needlessly global code static:

- arch_reinit_sched_domains()
- struct attr_sched_mc_power_savings
- struct attr_sched_smt_power_savings

Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-12 18:08:19 +02:00
Ingo Molnar 529c77261b sched: improve rq-clock overflow logic
improve the rq-clock overflow logic: limit the absolute rq->clock
delta since the last scheduler tick, instead of limiting the delta
itself.

tested by Arjan van de Ven - whole laptop was misbehaving due to
an incorrectly calibrated cpu_khz confusing sched_clock().

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
2007-08-10 23:05:11 +02:00
Ingo Molnar 194081ebfa sched: round a bit better
round a tiny bit better in high-frequency rescheduling scenarios,
by rounding around zero instead of rounding down.

(this is pretty theoretical though)

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:51 +02:00
Ingo Molnar 254753dc32 sched: make the multiplication table more accurate
do small deltas in the weight and multiplication constant table so
that the worst-case numeric error is better than 1:100000000. (8 digits)

the current error table is:

     nice       mult *   inv_mult   error
     ------------------------------------------
     -20:      88761 *      48388  -0.0000000065
     -19:      71755 *      59856  -0.0000000037
     -18:      56483 *      76040   0.0000000056
     -17:      46273 *      92818   0.0000000042
     -16:      36291 *     118348  -0.0000000065
     -15:      29154 *     147320  -0.0000000037
     -14:      23254 *     184698  -0.0000000009
     -13:      18705 *     229616  -0.0000000037
     -12:      14949 *     287308  -0.0000000009
     -11:      11916 *     360437  -0.0000000009
     -10:       9548 *     449829  -0.0000000009
      -9:       7620 *     563644  -0.0000000037
      -8:       6100 *     704093   0.0000000009
      -7:       4904 *     875809   0.0000000093
      -6:       3906 *    1099582  -0.0000000009
      -5:       3121 *    1376151  -0.0000000058
      -4:       2501 *    1717300   0.0000000009
      -3:       1991 *    2157191  -0.0000000035
      -2:       1586 *    2708050   0.0000000009
      -1:       1277 *    3363326   0.0000000014
       0:       1024 *    4194304   0.0000000000
       1:        820 *    5237765   0.0000000009
       2:        655 *    6557202   0.0000000033
       3:        526 *    8165337  -0.0000000079
       4:        423 *   10153587   0.0000000012
       5:        335 *   12820798   0.0000000079
       6:        272 *   15790321   0.0000000037
       7:        215 *   19976592  -0.0000000037
       8:        172 *   24970740  -0.0000000037
       9:        137 *   31350126  -0.0000000079
      10:        110 *   39045157  -0.0000000061
      11:         87 *   49367440  -0.0000000037
      12:         70 *   61356676   0.0000000056
      13:         56 *   76695844  -0.0000000075
      14:         45 *   95443717  -0.0000000072
      15:         36 *  119304647  -0.0000000009
      16:         29 *  148102320  -0.0000000037
      17:         23 *  186737708  -0.0000000028
      18:         18 *  238609294  -0.0000000009
      19:         15 *  286331153  -0.0000000002

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:51 +02:00
Ingo Molnar 6e82a3befe sched: optimize update_rq_clock() calls in the load-balancer
optimize update_rq_clock() calls in the load-balancer: update them
right after locking the runqueue(s) so that the pull functions do
not have to call it.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:51 +02:00
Ingo Molnar 2daa357705 sched: optimize activate_task()
optimize activate_task() by removing update_rq_clock() from it.
(and add update_rq_clock() to all callsites of activate_task() that
did not have it before.)

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:51 +02:00
Ingo Molnar 546fe3c909 sched: move the __update_rq_clock() call to scheduler_tick()
move the __update_rq_clock() call from update_cpu_load() to
scheduler_tick().

( identity transformation that causes no change in functionality. )

this allows the direct use of rq->clock in ->task_tick() functions.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:51 +02:00
Ingo Molnar bdd4dfa89c sched: remove the 'u64 now' local variables
final step: remove all (now superfluous) 'u64 now' variables.

( identity transformation that causes no change in functionality. )

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:51 +02:00
Ingo Molnar 2e1cb74a50 sched: remove the 'u64 now' parameter from deactivate_task()
remove the 'u64 now' parameter from deactivate_task().

( identity transformation that causes no change in functionality. )

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:49 +02:00
Ingo Molnar 69be72c13d sched: remove the 'u64 now' parameter from dequeue_task()
remove the 'u64 now' parameter from dequeue_task().

( identity transformation that causes no change in functionality. )

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:49 +02:00
Ingo Molnar 8159f87e2b sched: remove the 'u64 now' parameter from enqueue_task()
remove the 'u64 now' parameter from enqueue_task().

( identity transformation that causes no change in functionality. )

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:49 +02:00
Ingo Molnar db53181e41 sched: remove the 'u64 now' parameter from dec_nr_running()
remove the 'u64 now' parameter from dec_nr_running().

( identity transformation that causes no change in functionality. )

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:49 +02:00
Ingo Molnar e5fa2237b5 sched: remove the 'u64 now' parameter from inc_nr_running()
remove the 'u64 now' parameter from inc_nr_running().

( identity transformation that causes no change in functionality. )

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:49 +02:00
Ingo Molnar 79b5dddf83 sched: remove the 'u64 now' parameter from dec_load()
remove the 'u64 now' parameter from dec_load().

( identity transformation that causes no change in functionality. )

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:49 +02:00
Ingo Molnar 29b4b623fe sched: remove the 'u64 now' parameter from inc_load()
remove the 'u64 now' parameter from inc_load().

( identity transformation that causes no change in functionality. )

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:49 +02:00
Ingo Molnar 84a1d7a2f9 sched: remove the 'u64 now' parameter from update_curr_load()
remove the 'u64 now' parameter from update_curr_load().

( identity transformation that causes no change in functionality. )

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:49 +02:00
Ingo Molnar ee0827d8b5 sched: remove the 'u64 now' parameter from ->task_new()
remove the 'u64 now' parameter from ->task_new().

( identity transformation that causes no change in functionality. )

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:49 +02:00
Ingo Molnar 31ee529cc2 sched: remove the 'u64 now' parameter from ->put_prev_task()
remove the 'u64 now' parameter from ->put_prev_task().

( identity transformation that causes no change in functionality. )

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:49 +02:00
Ingo Molnar ff95f3df54 sched: remove the 'u64 now' parameter from pick_next_task()
remove the 'u64 now' parameter from pick_next_task().

( identity transformation that causes no change in functionality. )

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:49 +02:00
Ingo Molnar fb8d472402 sched: remove the 'u64 now' parameter from ->pick_next_task()
remove the 'u64 now' parameter from ->pick_next_task().

( identity transformation that causes no change in functionality. )

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:48 +02:00
Ingo Molnar f02231e51a sched: remove the 'u64 now' parameter from ->dequeue_task()
remove the 'u64 now' parameter from ->dequeue_task().

( identity transformation that causes no change in functionality. )

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:48 +02:00
Ingo Molnar fd390f6a04 sched: remove the 'u64 now' parameter from ->enqueue_task()
remove the 'u64 now' parameter from ->enqueue_task().

( identity transformation that causes no change in functionality. )

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:48 +02:00
Ingo Molnar d281918d7c sched: remove 'now' use from assignments
change all 'now' timestamp uses in assignments to rq->clock.

( this is an identity transformation that causes no functionality change:
  all such new rq->clock is necessarily preceded by an update_rq_clock()
  call. )

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:47 +02:00
Ingo Molnar eb59449400 sched: remove __rq_clock()
remove the (now unused) __rq_clock() function.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:47 +02:00
Ingo Molnar c1b3da3ecd sched: eliminate __rq_clock() use
eliminate __rq_clock() use by changing it to:

   __update_rq_clock(rq)
   now = rq->clock;

identity transformation - no change in behavior.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:47 +02:00
Ingo Molnar 2ab81159fa sched: remove rq_clock()
remove the now unused rq_clock() function.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:47 +02:00
Ingo Molnar a8e504d2a5 sched: eliminate rq_clock() use
eliminate rq_clock() use by changing it to:

   update_rq_clock(rq)
   now = rq->clock;

identity transformation - no change in behavior.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:47 +02:00
Ingo Molnar b04a0f4c16 sched: add [__]update_rq_clock(rq)
add the [__]update_rq_clock(rq) functions. (No change in functionality,
just reorganization to prepare for elimination of the heavy 64-bit
timestamp-passing in the scheduler.)

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:46 +02:00
Peter Williams a4ac01c36e sched: fix bug in balance_tasks()
There are two problems with balance_tasks() and how it used:

1. The variables best_prio and best_prio_seen (inherited from the old
move_tasks()) were only required to handle problems caused by the
active/expired arrays, the order in which they were processed and the
possibility that the task with the highest priority could be on either.
  These issues are no longer present and the extra overhead associated
with their use is unnecessary (and possibly wrong).

2. In the absence of CONFIG_FAIR_GROUP_SCHED being set, the same
this_best_prio variable needs to be used by all scheduling classes or
there is a risk of moving too much load.  E.g. if the highest priority
task on this at the beginning is a fairly low priority task and the rt
class migrates a task (during its turn) then that moved task becomes the
new highest priority task on this_rq but when the sched_fair class
initializes its copy of this_best_prio it will get the priority of the
original highest priority task as, due to the run queue locks being
held, the reschedule triggered by pull_task() will not have taken place.
  This could result in inappropriate overriding of skip_for_load and
excessive load being moved.

The attached patch addresses these problems by deleting all reference to
best_prio and best_prio_seen and making this_best_prio a reference
parameter to the various functions involved.

load_balance_fair() has also been modified so that this_best_prio is
only reset (in the loop) if CONFIG_FAIR_GROUP_SCHED is set.  This should
preserve the effect of helping spread groups' higher priority tasks
around the available CPUs while improving system performance when
CONFIG_FAIR_GROUP_SCHED isn't set.

Signed-off-by: Peter Williams <pwil3058@bigpond.net.au>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:46 +02:00
Alexey Dobriyan e0361851e5 sched: remove binary sysctls from kernel.sched_domain
kernel.sched_domain hierarchy is under CTL_UNNUMBERED and thus
unreachable to sysctl(2). Generating .ctl_number's in such situation is
not useful.

Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:46 +02:00
Ingo Molnar 8e717b194c sched: schedule() speedup
speed up schedule(): share the 'now' parameter that deactivate_task()
was calculating internally.

( this also fixes the small accounting window between the deactivate
  call and the pick_next_task() call. )

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:46 +02:00
Ingo Molnar 7bfd048587 sched: uninline rq_clock()
uninline rq_clock() to save 263 bytes of code:

   text    data     bss     dec     hex filename
   39561    3642      24   43227    a8db sched.o.before
   39298    3642      24   42964    a7d4 sched.o.after

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:46 +02:00
Ulrich Drepper 9531b62f5e sched: clean up sched_getaffinity()
here's another tiny cleanup.  The generated code is not affected (gcc is
smart enough) but for people looking over the code it is just irritating
to have the extra conditional.

Signed-off-by: Ulrich Drepper <drepper@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:46 +02:00
Peter Williams 4301065920 sched: simplify move_tasks()
The move_tasks() function is currently multiplexed with two distinct
capabilities:

1. attempt to move a specified amount of weighted load from one run
queue to another; and
2. attempt to move a specified number of tasks from one run queue to
another.

The first of these capabilities is used in two places, load_balance()
and load_balance_idle(), and in both of these cases the return value of
move_tasks() is used purely to decide if tasks/load were moved and no
notice of the actual number of tasks moved is taken.

The second capability is used in exactly one place,
active_load_balance(), to attempt to move exactly one task and, as
before, the return value is only used as an indicator of success or failure.

This multiplexing of sched_task() was introduced, by me, as part of the
smpnice patches and was motivated by the fact that the alternative, one
function to move specified load and one to move a single task, would
have led to two functions of roughly the same complexity as the old
move_tasks() (or the new balance_tasks()).  However, the new modular
design of the new CFS scheduler allows a simpler solution to be adopted
and this patch addresses that solution by:

1. adding a new function, move_one_task(), to be used by
active_load_balance(); and
2. making move_tasks() a single purpose function that tries to move a
specified weighted load and returns 1 for success and 0 for failure.

One of the consequences of these changes is that neither move_one_task()
or the new move_tasks() care how many tasks sched_class.load_balance()
moves and this enables its interface to be simplified by returning the
amount of load moved as its result and removing the load_moved pointer
from the argument list.  This helps simplify the new move_tasks() and
slightly reduces the amount of work done in each of
sched_class.load_balance()'s implementations.

Further simplification, e.g. changes to balance_tasks(), are possible
but (slightly) complicated by the special needs of load_balance_fair()
so I've left them to a later patch (if this one gets accepted).

NB Since move_tasks() gets called with two run queue locks held even
small reductions in overhead are worthwhile.

[ mingo@elte.hu ]

this change also reduces code size nicely:

   text    data     bss     dec     hex filename
   39216    3618      24   42858    a76a sched.o.before
   39173    3618      24   42815    a73f sched.o.after

Signed-off-by: Peter Williams <pwil3058@bigpond.net.au>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:46 +02:00
Ingo Molnar f1a438d813 sched: reorder update_cpu_load(rq) with the ->task_tick() call
Peter Williams suggested to flip the order of update_cpu_load(rq) with
the ->task_tick() call. This is a NOP for the current scheduler (the
two functions are independent of each other), ->task_tick() might
create some state for update_cpu_load() in the future (or in PlugSched).

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:45 +02:00
Ingo Molnar 6cfb0d5d06 [PATCH] sched: reduce debug code
move the rest of the debugging/instrumentation code to under
CONFIG_SCHEDSTATS too. This reduces code size and speeds code up:

    text    data     bss     dec     hex filename
   33044    4122      28   37194    914a sched.o.before
   32708    4122      28   36858    8ffa sched.o.after

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-02 17:41:40 +02:00
Ingo Molnar 9c2172459a [PATCH] sched: move load-calculation functions
move load-calculation functions so that they can use the per-policy
declarations and methods.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-02 17:41:40 +02:00
Ingo Molnar cad60d93e1 [PATCH] sched: ->task_new cleanup
make sched_class.task_new == NULL a 'default method', this
allows the removal of task_rt_new.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-02 17:41:40 +02:00
Ingo Molnar 4e6f96f313 [PATCH] sched: uninline inc/dec_nr_running()
uninline inc_nr_running() and dec_nr_running():

   text    data     bss     dec     hex filename
   29039    4162      24   33225    81c9 sched.o.before
   29027    4162      24   33213    81bd sched.o.after

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-02 17:41:40 +02:00
Ingo Molnar cb1c4fc924 [PATCH] sched: uninline calc_delta_mine()
uninline calc_delta_mine():

   text    data     bss     dec     hex filename
   29162    4162      24   33348    8244 sched.o.before
   29039    4162      24   33225    81c9 sched.o.after

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-02 17:41:40 +02:00
Ingo Molnar ecf691daf7 [PATCH] sched: calc_delta_mine(): use fixed limit
use fixed limit in calc_delta_mine() - this saves an instruction :)

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-02 17:41:40 +02:00
Peter Williams 5a4f3ea77e [PATCH] sched: tidy up left over smpnice code
1. The only place that RTPRIO_TO_LOAD_WEIGHT() is used is in the call to
move_tasks() in the function active_load_balance() and its purpose here
is just to make sure that the load to be moved is big enough to ensure
that exactly one task is moved (if there's one available).  This can be
accomplished by using ULONG_MAX instead and this allows
RTPRIO_TO_LOAD_WEIGHT() to be deleted.

2. This, in turn, allows PRIO_TO_LOAD_WEIGHT() to be deleted.

3. This allows load_weight() to be deleted which allows
TIME_SLICE_NICE_ZERO to be deleted along with the comment above it.

Signed-off-by: Peter Williams <pwil3058@bigpond.net.au>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-02 17:41:40 +02:00
Ingo Molnar 362a701663 [PATCH] sched: remove cache_hot_time
remove the last unused remains of cache_hot_time.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-02 17:41:40 +02:00
Randy Dunlap 421cee2935 sched: fix kernel-doc warnings
Fix kernel-doc warnings in sched.c:

Warning(linux-2623-rc1g4//kernel/sched.c:1685): No description found for parameter 'notifier'
Warning(linux-2623-rc1g4//kernel/sched.c:1696): No description found for parameter 'notifier'
Warning(linux-2623-rc1g4//kernel/sched.c:1750): No description found for parameter 'prev'

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-31 15:39:38 -07:00
Nick Piggin e692ab5347 [PATCH] sched: debug feature - make the sched-domains tree runtime-tweakable
debugging feature: make the sched-domains tree runtime-tweakable.

Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
[ mingo@elte.hu: made it depend on CONFIG_SCHED_DEBUG & small updates ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-07-26 13:40:43 +02:00
Ingo Molnar 2cd4d0ea19 [PATCH] sched: make cpu_clock() not use the rq clock
it is enough to disable interrupts to get the precise rq-clock
of the local CPU.

this also solves an NMI watchdog regression: the NMI watchdog
calls touch_softlockup_watchdog(), which might deadlock on
rq->lock if the NMI hits an rq-locked critical section.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-07-26 13:40:43 +02:00
Satoru Takeuchi 018a221295 [PATCH] sched: remove unused rq->load_balance_class
Remove unused rq->load_balance_class.

Signed-off-by: Satoru Takeuchi <takeuchi_satoru@jp.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-07-26 13:40:43 +02:00
Avi Kivity e107be36ef [PATCH] sched: arch preempt notifier mechanism
This adds a general mechanism whereby a task can request the scheduler to
notify it whenever it is preempted or scheduled back in.  This allows the
task to swap any special-purpose registers like the fpu or Intel's VT
registers.

Signed-off-by: Avi Kivity <avi@qumranet.com>
[ mingo@elte.hu: fixes, cleanups ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-07-26 13:40:43 +02:00
Ingo Molnar e436d80085 [PATCH] sched: implement cpu_clock(cpu) high-speed time source
Implement the cpu_clock(cpu) interface for kernel-internal use:
high-speed (but slightly incorrect) per-cpu clock constructed from
sched_clock().

This API, unused at the moment, will be used in the future by blktrace,
by the softlockup-watchdog, by printk and by lockstat.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-07-19 21:28:35 +02:00
Suresh Siddha 969bb4e403 [PATCH] sched: fix the all pinned logic in load_balance_newidle()
nr_moved is not the correct check for triggering all pinned logic. Fix
the all pinned logic in the case of load_balance_newidle().

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-07-19 21:28:35 +02:00
Suresh Siddha 9439aab8db [PATCH] sched: fix newly idle load balance in case of SMT
In the presence of SMT, newly idle balance was never happening for
multi-core and SMP domains (even when both the logical siblings are
idle).

If thread 0 is already idle and when thread 1 is about to go to idle,
newly idle load balance always think that one of the threads is not idle
and skips doing the newly idle load balance for multi-core and SMP
domains.

This is because of the idle_cpu() macro, which checks if the current
process on a cpu is an idle process. But this is not the case for the
thread doing the load_balance_newidle().

Fix this by using runqueue's nr_running field instead of idle_cpu(). And
also skip the logic of 'only one idle cpu in the group will be doing
load balancing' during newly idle case.

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-07-19 21:28:35 +02:00
Fenghua Yu f34e3b61f2 use the new percpu interface for shared data
Currently most of the per cpu data, which is accessed by different cpus,
has a ____cacheline_aligned_in_smp attribute.  Move all this data to the
new per cpu shared data section: .data.percpu.shared_aligned.

This will seperate the percpu data which is referenced frequently by other
cpus from the local only percpu data.

Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Acked-by: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-19 10:04:45 -07:00
Rafael J. Wysocki 8314418629 Freezer: make kernel threads nonfreezable by default
Currently, the freezer treats all tasks as freezable, except for the kernel
threads that explicitly set the PF_NOFREEZE flag for themselves.  This
approach is problematic, since it requires every kernel thread to either
set PF_NOFREEZE explicitly, or call try_to_freeze(), even if it doesn't
care for the freezing of tasks at all.

It seems better to only require the kernel threads that want to or need to
be frozen to use some freezer-related code and to remove any
freezer-related code from the other (nonfreezable) kernel threads, which is
done in this patch.

The patch causes all kernel threads to be nonfreezable by default (ie.  to
have PF_NOFREEZE set by default) and introduces the set_freezable()
function that should be called by the freezable kernel threads in order to
unset PF_NOFREEZE.  It also makes all of the currently freezable kernel
threads call set_freezable(), so it shouldn't cause any (intentional)
change of behaviour to appear.  Additionally, it updates documentation to
describe the freezing of tasks more accurately.

[akpm@linux-foundation.org: build fixes]
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Nigel Cunningham <nigel@nigel.suspend2.net>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Gautham R Shenoy <ego@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-17 10:23:02 -07:00
Ingo Molnar e4af30be8f [PATCH] sched: prettify prio_to_wmult[]
prettify the prio_to_wmult[] array. (this could have saved us from the typos)

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-07-16 09:46:31 +02:00
Ingo Molnar 5714d2de93 [PATCH] sched: document prio_to_wmult[]
document prio_to_wmult[].

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-07-16 09:46:31 +02:00
Ingo Molnar f9153ee6c7 [PATCH] sched: improve weight-array comments
improve the comments around the wmult array (which controls the weight
of niced tasks). Clarify that to achieve a 10% difference in CPU
utilization, a weight multiplier of 1.25 has to be used.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-07-16 09:46:30 +02:00
Thomas Gleixner 4fd885170b CFS: Fix missing digit off in wmult table
Roman Zippel noticed another inconsistency of the wmult table.

wmult[16] has a missing digit.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-13 16:45:43 -07:00
Ingo Molnar 4bd77321a8 [PATCH] sched: fix show_task()/show_tasks() output
fix show_task()/show_tasks() output:

- there's no sibling info anymore

- the fields were not aligned properly with the description

- get rid of the lazy-TLB output: it's been quite some time since
  we last had a bug there, and when we had a bug it wasnt helped a
  bit by this debug output.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-13 10:11:17 -07:00
Ingo Molnar a5968df873 [PATCH] sched: allow larger granularity
Allow granularity up to 100 msecs, instead of 10 msecs.
(needed on larger boxes)

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-13 10:10:08 -07:00
Mike Galbraith e127031f4f [PATCH] sched: fix prio_to_wmult[] for nice 1
There's a typo in the values in prio_to_wmult[] for nice level 1.  While
it did not cause bad CPU distribution, but caused more rescheduling
between nice-0 and nice-1 tasks than necessary.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-13 10:09:02 -07:00
Ingo Molnar c31f2e8a42 sched: add CFS credits
add credits for recent major scheduler contributions:

  Con Kolivas, for pioneering the fair-scheduling approach
  Peter Williams, for smpnice
  Mike Galbraith, for interactivity tuning of CFS
  Srivatsa Vaddagiri, for group scheduling enhancements

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-07-09 18:52:01 +02:00
Ingo Molnar 0fec171cdb sched: clean up sleep_on() APIs
clean up the sleep_on() APIs:

 - do not use fastcall
 - replace fragile macro magic with proper inline functions

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-07-09 18:52:01 +02:00
Ingo Molnar 9761eea851 sched: style cleanups
4 small style cleanups to sched.c: checkpatch.pl is now happy about
the totality of sched.c [ignoring false positives] - yay! ;-)

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-07-09 18:52:00 +02:00
Ingo Molnar b2cfba19f6 sched: remove unused rq types from sched.c
remove unused rq types from sched.c, now that we switched
over to CFS.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-07-09 18:52:00 +02:00
Ingo Molnar 634fa8c97c sched: remove interactivity types
remove now unused interactivity-heuristics related defined and
types of the old scheduler.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-07-09 18:52:00 +02:00
Ingo Molnar dff06c157b sched: clean up include files in sched.c
clean up include files in sched.c, they were still old-style <asm/>.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-07-09 18:52:00 +02:00
Ingo Molnar 1b9f19c212 sched: turn on the use of unstable events
make use of sched-clock-unstable events.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-07-09 18:51:59 +02:00
Ingo Molnar bb29ab2686 sched: x86, track TSC-unstable events
track TSC-unstable events and propagate it to the scheduler code.
Also allow sched_clock() to be used when the TSC is unstable,
the rq_clock() wrapper creates a reliable clock out of it.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-07-09 18:51:59 +02:00
Ingo Molnar dd41f596cd sched: cfs core code
apply the CFS core code.

this change switches over the scheduler core to CFS's modular
design and makes use of kernel/sched_fair/rt/idletask.c to implement
Linux's scheduling policies.

thanks to Andrew Morton and Thomas Gleixner for lots of detailed review
feedback and for fixlets.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Dmitry Adamushko <dmitry.adamushko@gmail.com>
Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
2007-07-09 18:51:59 +02:00
Ingo Molnar f3479f10c5 sched: remove the sleep-bonus interactivity code
remove the sleep-bonus interactivity code from the core scheduler.

scheduling policy is implemented in the policy modules, and CFS does
not need such type of heuristics.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-07-09 18:51:59 +02:00
Ingo Molnar c18a17329b sched: remove expired_starving()
remove the expired_starving() heuristics from the core scheduler.

CFS does not need it, and this did not really work well in practice
anyway, due to the rq->nr_running multiplier to STARVATION_LIMIT.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-07-09 18:51:59 +02:00
Ingo Molnar f2ac58ee61 sched: remove sleep_type
remove the sleep_type heuristics from the core scheduler - scheduling
policy is implemented in the scheduling-policy modules. (and CFS does
not use this type of sleep-type heuristics)

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-07-09 18:51:59 +02:00
Ingo Molnar 45bf76df48 sched: cfs, add load-calculation methods
add the new load-calculation methods of CFS.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-07-09 18:51:59 +02:00
Ingo Molnar 14531189f0 sched: clean up __normal_prio() position
clean up: move __normal_prio() in head of normal_prio().

no code changed.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-07-09 18:51:59 +02:00
Ingo Molnar 71f8bd4600 sched: cleanup: move dequeue/enqueue_task()
cleanup: move dequeue/enqueue_task() to a more logical place, to
not split up __normal_prio()/normal_prio().

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-07-09 18:51:59 +02:00
Ingo Molnar c24d20dbef sched: move around resched_task()
move resched_task()/resched_cpu() into the 'public interfaces'
section of sched.c, for use by kernel/sched_fair/rt/idletask.c

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-07-09 18:51:59 +02:00
Ingo Molnar e05606d330 sched: clean up the rt priority macros
clean up the rt priority macros, pointed out by Andrew Morton.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-07-09 18:51:59 +02:00
Ingo Molnar 138a8aeb5b sched: add cfs_rq ops
add the set_task_cfs_rq() abstraction needed by CONFIG_FAIR_GROUP_SCHED.

(not activated yet)

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-07-09 18:51:58 +02:00
Ingo Molnar 41b86e9c51 sched: make posix-cpu-timers use CFS's accounting information
update the posix-cpu-timers code to use CFS's CPU accounting information.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-07-09 18:51:58 +02:00
Ingo Molnar 20d315d42a sched: add rq_clock()/__rq_clock()
add rq_clock()/__rq_clock(), a robust wrapper around sched_clock(),
used by CFS. It protects against common type of sched_clock() problems
(caused by hardware): time warps forwards and backwards.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-07-09 18:51:58 +02:00
Ingo Molnar 6aa645ea5f sched: cfs rq data types
add the CFS rq data types to sched.c.

(the old scheduler fields are still intact, they are removed
 by a later patch)

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-07-09 18:51:58 +02:00
Ingo Molnar 425e0968a2 sched: move code into kernel/sched_stats.h
create sched_stats.h and move sched.c schedstats code into it.
This cleans up sched.c a bit.

no code changes are caused by this patch.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-07-09 18:51:58 +02:00
Ingo Molnar 1df21055e3 sched: add init_idle_bootup_task()
add the init_idle_bootup_task() callback to the bootup thread,
unused at the moment. (CFS will use it to switch the scheduling
class of the boot thread to the idle class)

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-07-09 18:51:58 +02:00
Ingo Molnar f64f61145a sched: remove sched_exit()
remove sched_exit(): the elaborate dance of us trying to recover
timeslices given to child tasks never really worked.

CFS does not need it either.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-07-09 18:51:58 +02:00
Ingo Molnar c65cc87052 sched: uninline set_task_cpu()
uninline set_task_cpu(): CFS will add more code to it.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-07-09 18:51:58 +02:00
Ingo Molnar 0437e109e1 sched: zap the migration init / cache-hot balancing code
the SMP load-balancer uses the boot-time migration-cost estimation
code to attempt to improve the quality of balancing. The reason for
this code is that the discrete priority queues do not preserve
the order of scheduling accurately, so the load-balancer skips
tasks that were running on a CPU 'recently'.

this code is fundamental fragile: the boot-time migration cost detector
doesnt really work on systems that had large L3 caches, it caused boot
delays on large systems and the whole cache-hot concept made the
balancing code pretty undeterministic as well.

(and hey, i wrote most of it, so i can say it out loud that it sucks ;-)

under CFS the same purpose of cache affinity can be achieved without
any special cache-hot special-case: tasks are sorted in the 'timeline'
tree and the SMP balancer picks tasks from the left side of the
tree, thus the most cache-cold task is balanced automatically.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-07-09 18:51:57 +02:00
Ingo Molnar d15bcfdbe1 sched: rename idle_type/SCHED_IDLE
enum idle_type (used by the load-balancer) clashes with the
SCHED_IDLE name that we want to introduce. 'CPU_IDLE' instead
of 'SCHED_IDLE' is more descriptive as well.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-07-09 18:51:57 +02:00
Christoph Lameter 92c4ca5c3a sched: fix next_interval determination in idle_balance()
The intervals of domains that do not have SD_BALANCE_NEWIDLE must be
considered for the calculation of the time of the next balance.  Otherwise
we may defer rebalancing forever.

Siddha also spotted that the conversion of the balance interval
to jiffies is missing. Fix that to.

From: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>

also continue the loop if !(sd->flags & SD_LOAD_BALANCE).

Tested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

It did in fact trigger under all three of mainline, CFS, and -rt including CFS
-- see below for a couple of emails from last Friday giving results for these
three on the AMD box (where it happened) and on a single-quad NUMA-Q system
(where it did not, at least not with such severity).

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-06-24 08:59:11 -07:00
Linus Torvalds fa490cfd15 Fix possible runqueue lock starvation in wait_task_inactive()
Miklos Szeredi reported very long pauses (several seconds, sometimes
more) on his T60 (with a Core2Duo) which he managed to track down to
wait_task_inactive()'s open-coded busy-loop.

He observed that an interrupt on one core tries to acquire the
runqueue-lock but does not succeed in doing so for a very long time -
while wait_task_inactive() on the other core loops waiting for the first
core to deschedule a task (which it wont do while spinning in an
interrupt handler).

This rewrites wait_task_inactive() to do all its waiting optimistically
without any locks taken at all, and then just double-check the end
result with the proper runqueue lock held over just a very short
section.  If there were races in the optimistic wait, of a preemption
event scheduled the process away, we simply re-synchronize, and start
over.

So the code now looks like this:

	repeat:
		/* Unlocked, optimistic looping! */
		rq = task_rq(p);
		while (task_running(rq, p))
			cpu_relax();

		/* Get the *real* values */
		rq = task_rq_lock(p, &flags);
		running = task_running(rq, p);
		array = p->array;
		task_rq_unlock(rq, &flags);

		/* Check them.. */
		if (unlikely(running)) {
			cpu_relax();
			goto repeat;
		}

		/* Preempted away? Yield if so.. */
		if (unlikely(array)) {
			yield();
			goto repeat;
		}

Basically, that first "while()" loop is done entirely without any
locking at all (and doesn't check for the case where the target process
might have been preempted away), and so it's possibly "incorrect", but
we don't really care.  Both the runqueue used, and the "task_running()"
check might be the wrong tests, but they won't oops - they just mean
that we could possibly get the wrong results due to lack of locking and
exit the loop early in the case of a race condition.

So once we've exited the loop, we then get the proper (and careful) rq
lock, and check the running/runnable state _safely_.  And if it turns
out that our quick-and-dirty and unsafe loop was wrong after all, we
just go back and try it all again.

(The patch also adds a lot of comments, which is the actual bulk of it
all, to make it more obvious why we can do these things without holding
the locks).

Thanks to Miklos for all the testing and tracking it down.

Tested-by: Miklos Szeredi <miklos@szeredi.hu>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-06-18 11:52:55 -07:00
Ingo Molnar a0f98a1cb7 sched: fix SysRq-N (normalize RT tasks)
Gene Heskett reported the following problem while testing CFS: SysRq-N
is not always effective in normalizing tasks back to SCHED_OTHER.

The reason for that turns out to be the following bug:

 - normalize_rt_tasks() uses for_each_process() to iterate through all
   tasks in the system.  The problem is, this method does not iterate
   through all tasks, it iterates through all thread groups.

The proper mechanism to enumerate over all threads is to use a
do_each_thread() + while_each_thread() loop.

Reported-by: Gene Heskett <gene.heskett@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-06-18 11:52:55 -07:00
Thomas Gleixner 98d8256739 Prevent going idle with softirq pending
The NOHZ patch contains a check for softirqs pending when a CPU goes idle.
The BUG is unrelated to NOHZ, it just was made visible by the NOHZ patch.
The BUG showed up mainly on P4 / hyperthreading enabled machines which lead
the investigations into the wrong direction in the first place.  The real
cause is in cond_resched_softirq():

cond_resched_softirq() is enabling softirqs without invoking the softirq
daemon when softirqs are pending.  This leads to the warning message in the
NOHZ idle code:

t1 runs softirq disabled code on CPU#0
interrupt happens, softirq is raised, but deferred (softirqs disabled)
t1 calls cond_resched_softirq()
	enables softirqs via _local_bh_enable()
	calls schedule()
t2 runs
t1 is migrated to CPU#1
t2 is done and invokes idle()
NOHZ detects the pending softirq

Fix: change _local_bh_enable() to local_bh_enable() so the softirq
daemon is invoked.

Thanks to Anant Nitya for debugging this with great patience !

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-23 20:14:15 -07:00
Rafael J. Wysocki 8bb7844286 Add suspend-related notifications for CPU hotplug
Since nonboot CPUs are now disabled after tasks and devices have been
frozen and the CPU hotplug infrastructure is used for this purpose, we need
special CPU hotplug notifications that will help the CPU-hotplug-aware
subsystems distinguish normal CPU hotplug events from CPU hotplug events
related to a system-wide suspend or resume operation in progress.  This
patch introduces such notifications and causes them to be used during
suspend and resume transitions.  It also changes all of the
CPU-hotplug-aware subsystems to take these notifications into consideration
(for now they are handled in the same way as the corresponding "normal"
ones).

[oleg@tv-sign.ru: cleanups]
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Gautham R Shenoy <ego@in.ibm.com>
Cc: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-09 12:30:56 -07:00
Gautham R Shenoy 5be9361cdf Eliminate lock_cpu_hotplug in kernel/schedc
Eliminate lock_cpu_hotplug from kernel/sched.c and use sched_hotcpu_mutex
instead to postpone a hotplug event.

In the migration_call hotcpu callback function, take sched_hotcpu_mutex
while handling the event CPU_LOCK_ACQUIRE and release it while handling
CPU_LOCK_RELEASE event.

[akpm@linux-foundation.org: fix deadlock]
Signed-off-by: Gautham R Shenoy <ego@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-09 12:30:51 -07:00
Andrew Morton d5f9f942c6 revert 'sched: redundant reschedule when set_user_nice() boosts a prio of a task from the "expired" array'
Revert commit bd53f96ca5.

Con says:

This is no good, sorry. The one I saw originally was with the staircase
deadline cpu scheduler in situ and was different.

  #define TASK_PREEMPTS_CURR(p, rq) \
     ((p)->prio < (rq)->curr->prio)
     (((p)->prio < (rq)->curr->prio) && ((p)->array == (rq)->active))

This will fail to wake up a runqueue for a task that has been migrated to the
expired array of a runqueue which is otherwise idle which can happen with smp
balancing,

Cc: Dmitry Adamushko <dmitry.adamushko@gmail.com>
Cc: Con Kolivas <kernel@kolivas.org>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-08 20:41:15 -07:00
Siddha, Suresh B c3396620ca sched: align rq to cacheline boundary
Align the per cpu runqueue to the cacheline boundary.  This will minimize
the number of cachelines touched during remote wakeup.

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Ravikiran G Thirumalai <kiran@scalex86.org>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-08 11:15:17 -07:00
Dmitry Adamushko bd53f96ca5 sched: redundant reschedule when set_user_nice() boosts a prio of a task from the "expired" array
- Make TASK_PREEMPTS_CURR(task, rq) return "true" only if the task's prio
  is higher than the current's one and the task is in the "active" array.
  This ensures we don't make redundant resched_task() calls when the task
  is in the "expired" array (as may happen now in set_user_prio(),
  rt_mutex_setprio() and pull_task() ) ;

- generalise conditions for a call to resched_task() in set_user_nice(),
  rt_mutex_setprio() and sched_setscheduler()

Signed-off-by: Dmitry Adamushko <dmitry.adamushko@gmail.com>
Cc: Con Kolivas <kernel@kolivas.org>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-08 11:15:17 -07:00
Siddha, Suresh B 4953198b6c sched: optimize siblings status check logic in wake_idle()
When a logical cpu 'x' already has more than one process running, then most
likely the siblings of that cpu 'x' must be busy.  Otherwise the idle
siblings would have likely(in most of the scenarios) picked up the extra
load making the load on 'x' atmost one.

Use this logic to eliminate the siblings status check and minimize the cache
misses encountered on a heavily loaded system.

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-08 11:15:17 -07:00
Eric Dumazet 5517d86bea Speed up divides by cpu_power in scheduler
I noticed expensive divides done in try_to_wakeup() and
find_busiest_group() on a bi dual core Opteron machine (total of 4 cores),
moderatly loaded (15.000 context switch per second)

oprofile numbers :

CPU: AMD64 processors, speed 2600.05 MHz (estimated)
Counted CPU_CLK_UNHALTED events (Cycles outside of halt state) with a unit
mask of 0x00 (No unit mask) count 50000
samples  %        symbol name
...
613914    1.0498  try_to_wake_up
    834  0.0013 :ffffffff80227ae1:   div    %rcx
77513  0.1191 :ffffffff80227ae4:   mov    %rax,%r11

608893    1.0413  find_busiest_group
   1841  0.0031 :ffffffff802260bf:       div    %rdi
140109  0.2394 :ffffffff802260c2:       test   %sil,%sil

Some of these divides can use the reciprocal divides we introduced some
time ago (currently used in slab AFAIK)

We can assume a load will fit in a 32bits number, because with a
SCHED_LOAD_SCALE=128 value, its still a theorical limit of 33554432

When/if we reach this limit one day, probably cpus will have a fast
hardware divide and we can zap the reciprocal divide trick.

Ingo suggested to rename cpu_power to __cpu_power to make clear it should
not be modified without changing its reciprocal value too.

I did not convert the divide in cpu_avg_load_per_task(), because tracking
nr_running changes may be not worth it ?  We could use a static table of 32
reciprocal values but it would add a conditional branch and table lookup.

[akpm@linux-foundation.org: !SMP build fix]
Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-08 11:15:17 -07:00
Siddha, Suresh B 46cb4b7c88 sched: dynticks idle load balancing
Fix the process idle load balancing in the presence of dynticks.  cpus for
which ticks are stopped will sleep till the next event wakes it up.
Potentially these sleeps can be for large durations and during which today,
there is no periodic idle load balancing being done.

This patch nominates an owner among the idle cpus, which does the idle load
balancing on behalf of the other idle cpus.  And once all the cpus are
completely idle, then we can stop this idle load balancing too.  Checks added
in fast path are minimized.  Whenever there are busy cpus in the system, there
will be an owner(idle cpu) doing the system wide idle load balancing.

Open items:
1. Intelligent owner selection (like an idle core in a busy package).
2. Merge with rcu's nohz_cpu_mask?

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-08 11:15:17 -07:00
Siddha, Suresh B bdecea3a92 sched: fix idle load balancing in softirqd context
Periodic load balancing in recent kernels happen in the softirq.  In
certain -rt configurations, these softirqs are handled in softirqd context.
 And hence the check for idle processor was always returning busy (as
nr_running > 1).

This patch captures the idle information at the tick and passes this info
to softirq context through an element 'idle_at_tick' in rq.

[kernel@kolivas.org: Fix reverse idle at tick logic]
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-08 11:15:17 -07:00
Jeremy Fitzhardinge 04c9167f91 add touch_all_softlockup_watchdogs()
Add touch_all_softlockup_watchdogs() to allow the softlockup watchdog
timers on all cpus to be updated.  This is used to prevent sysrq-t from
generating a spurious watchdog message when generating lots of output.

Softlockup watchdogs use sched_clock() as its timebase, which is inherently
per-cpu (at least, when it is measuring unstolen time).  Because of this,
it isn't possible for one CPU to directly update the other CPU's timers,
but it is possible to tell the other CPUs to do update themselves
appropriately.

Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Acked-by: Chris Lalancette <clalance@redhat.com>
Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Cc: Rick Lindsley <ricklind@us.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-08 11:15:06 -07:00
Christoph Lameter 476f35348e Safer nr_node_ids and nr_node_ids determination and initial values
The nr_cpu_ids value is currently only calculated in smp_init.  However, it
may be needed before (SLUB needs it on kmem_cache_init!) and other kernel
components may also want to allocate dynamically sized per cpu array before
smp_init.  So move the determination of possible cpus into sched_init()
where we already loop over all possible cpus early in boot.

Also initialize both nr_node_ids and nr_cpu_ids with the highest value they
could take.  If we have accidental users before these values are determined
then the current valud of 0 may cause too small per cpu and per node arrays
to be allocated.  If it is set to the maximum possible then we only waste
some memory for early boot users.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-07 12:12:51 -07:00
Ingo Molnar 39bc89fd40 make SysRq-T show all tasks again
show_state() (SysRq-T) developed the buggy habbit of not showing
TASK_RUNNING tasks.  This was due to the mistaken belief that state_filter
== -1 would be a pass-through filter - while in reality it did not let
TASK_RUNNING == 0 p->state values through.

Fix this by restoring the original '!state_filter means all tasks'
special-case i had in the original version.  Test-built and test-booted on
i686, SysRq-T now works as intended.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-04-27 10:46:51 -07:00
Linus Torvalds d354d2f4a6 sched.c: Remove unused variable 'relative'
Getting rid of the p->children printout in show_task() left behind an
unused variable.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-04-07 10:18:33 -07:00
Ingo Molnar 35f6f753b7 [PATCH] sched: get rid of p->children use in show_task()
the p->parent PID printout gives us all the information about the
task tree that we need - the eldest_child()/older_sibling()/
younger_sibling() printouts are mostly historic and i do not
remember ever having used those fields. (IMO in fact they confuse
the SysRq-T output.) So remove them.

This code has sentimental value though, those fields and
printouts are one of the oldest ones still surviving from
Linux v0.95's kernel/sched.c:

        if (p->p_ysptr || p->p_osptr)
                printk("   Younger sib=%d, older sib=%d\n\r",
                        p->p_ysptr ? p->p_ysptr->pid : -1,
                        p->p_osptr ? p->p_osptr->pid : -1);
        else
                printk("\n\r");

written 15 years ago, in early 1992.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus 'snif' Torvalds <torvalds@linux-foundation.org>
2007-04-07 10:06:51 -07:00
Con Kolivas 69f7c0a1be [PATCH] sched: remove SMT nice
Remove the SMT-nice feature which idles sibling cpus on SMT cpus to
facilitiate nice working properly where cpu power is shared.  The idling of
cpus in the presence of runnable tasks is considered too fragile, easy to
break with outside code, and the complexity of managing this system if an
architecture comes along with many logical cores sharing cpu power will be
unworkable.

Remove the associated per_cpu_gain variable in sched_domains used only by
this code.

Also:

  The reason is that with dynticks enabled, this code breaks without yet
  further tweaks so dynticks brought on the rapid demise of this code.  So
  either we tweak this code or kill it off entirely.  It was Ingo's preference
  to kill it off.  Either way this needs to happen for 2.6.21 since dynticks
  has gone in.

Signed-off-by: Con Kolivas <kernel@kolivas.org>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-03-05 07:57:51 -08:00
Ingo Molnar 7355690ead [PATCH] sched: fix SMT scheduler bug
The SMT scheduler incorrectly skips kernel threads even if they are
runnable (but they are preempted by a higher-prio user-space task which got
SMT-delayed by an even higher-priority task running on a sibling CPU).

Fix this for now by only doing the SMT-nice optimization if the
to-be-delayed task is the only runnable task.  (This should cover most of
the real-life cases anyway.)

This bug has been in the SMT scheduler since 2.6.17 or so, but has only
been noticed now by the active check in the dynticks code.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Michal Piotrowski <michal.k.k.piotrowski@gmail.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-03-01 14:53:38 -08:00
Thomas Gleixner c1e16aa279 [PATCH] Fix posix-cpu-timer breakage caused by stale p->last_ran value
Problem description at:
http://bugzilla.kernel.org/show_bug.cgi?id=8048

Commit b18ec80396
    [PATCH] sched: improve migration accuracy
optimized the scheduler time calculations, but broke posix-cpu-timers.

The problem is that the p->last_ran value is not updated after a context
switch.  So a subsequent call to current_sched_time() calculates with a
stale p->last_ran value, i.e.  accounts the full time, which the task was
scheduled away.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-03-01 14:53:37 -08:00
Zachary Amsden 9226d125d9 [PATCH] i386: paravirt CPU hypercall batching mode
The VMI ROM has a mode where hypercalls can be queued and batched.  This turns
out to be a significant win during context switch, but must be done at a
specific point before side effects to CPU state are visible to subsequent
instructions.  This is similar to the MMU batching hooks already provided.
The same hooks could be used by the Xen backend to implement a context switch
multicall.

To explain a bit more about lazy modes in the paravirt patches, basically, the
idea is that only one of lazy CPU or MMU mode can be active at any given time.
 Lazy MMU mode is similar to this lazy CPU mode, and allows for batching of
multiple PTE updates (say, inside a remap loop), but to avoid keeping some
kind of state machine about when to flush cpu or mmu updates, we just allow
one or the other to be active.  Although there is no real reason a more
comprehensive scheme could not be implemented, there is also no demonstrated
need for this extra complexity.

Signed-off-by: Zachary Amsden <zach@vmware.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Andi Kleen <ak@suse.de>
Cc: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
2007-02-13 13:26:21 +01:00
Nick Piggin ff91691bcc [PATCH] sched: avoid div in rebalance_tick
Avoid expensive integer divide 3 times per CPU per tick.

A userspace test of this loop went from 26ns, down to 19ns on a G5; and
from 123ns down to 28ns on a P3.

(Also avoid a variable bit shift, as suggested by Alan. The effect
of this wasn't noticable on the CPUs I tested with).

Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-12 09:48:37 -08:00
Robert P. J. Day 72fd4a35a8 [PATCH] Numerous fixes to kernel-doc info in source files.
A variety of (mostly) innocuous fixes to the embedded kernel-doc content in
source files, including:

  * make multi-line initial descriptions single line
  * denote some function names, constants and structs as such
  * change erroneous opening '/*' to '/**' in a few places
  * reword some text for clarity

Signed-off-by: Robert P. J. Day <rpjday@mindspring.com>
Cc: "Randy.Dunlap" <rdunlap@xenotime.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-11 10:51:32 -08:00
Alexey Dobriyan b035b6de24 [PATCH] Consolidate default sched_clock()
Use attribute(weak).

Signed-off-by: Alexey Dobriyan <adobriyan@openvz.org>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-11 10:51:28 -08:00
Nathan Lynch e5e5673f82 [PATCH] sched: tasks cannot run on cpus onlined after boot
Commit 5c1e176781 ("sched: force /sbin/init
off isolated cpus") sets init's cpus_allowed to a subset of cpu_online_map
at boot time, which means that tasks won't be scheduled on cpus that are
added to the system later.

Make init's cpus_allowed a subset of cpu_possible_map instead.  This should
still preserve the behavior that Nick's change intended.

Thanks to Giuliano Pochini for reporting this and testing the fix:

http://ozlabs.org/pipermail/linuxppc-dev/2006-December/029397.html

Signed-off-by: Nathan Lynch <ntl@pobox.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2007-01-11 18:18:20 -08:00
Ingo Molnar 9414232fa0 [PATCH] sched: fix cond_resched_softirq() offset
Remove the __resched_legal() check: it is conceptually broken.  The biggest
problem it had is that it can mask buggy cond_resched() calls.  A
cond_resched() call is only legal if we are not in an atomic context, with
two narrow exceptions:

 - if the system is booting
 - a reacquire_kernel_lock() down() done while PREEMPT_ACTIVE is set

But __resched_legal() hid this and just silently returned whenever
these primitives were called from invalid contexts. (Same goes for
cond_resched_locked() and cond_resched_softirq()).

Furthermore, the __legal_resched(0) call was buggy in that it caused
unnecessarily long softirq latencies via cond_resched_softirq().  (which is
only called from softirq-off sections, hence the code did nothing.)

The fix is to resurrect the efficiency of the might_sleep checks and to
only allow the narrow exceptions.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-30 10:56:41 -08:00
Tim Chen 67af63a6ab [PATCH] sched: remove __cpuinitdata anotation to cpu_isolated_map
The structure cpu_isolated_map is used not only during initialization.
Multi-core scheduler configuration changes and exclusive cpusets
use this during run time.  During setting of sched_mc_power_savings
 policy, this structure is accessed to update sched_domains.

Signed-off-by: Tim Chen <tim.c.chen@intel.com>
Acked-by: Suresh Siddha <suresh.b.siddha@intel.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-22 08:55:47 -08:00
Mark Fasheh ba0084048a [PATCH] Conditionally check expected_preempt_count in __resched_legal()
Commit 2d7d253548 ("fix cond_resched() fix")
introduced an 'expected_preempt_count' parameter to __resched_legal() to
fix a bug where it was returning a false negative when called from
cond_resched_lock() and preemption was enabled.

Unfortunately this broke things for when preemption is disabled.
preempt_count() will always return zero, thus failing the check against any
value of expected_preempt_count not equal to zero.  cond_resched_lock() for
example, passes an expected_preempt_count value of 1.

So fix the fix for the cond_resched() fix by skipping the check of
preempt_count() against expected_preempt_count when preemption is disabled.

Credit should go to Sunil Mushran for spotting the bug during testing.

Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-22 08:55:46 -08:00
Peter Williams bc947631d1 [PATCH] sched: improve efficiency of sched_fork()
Problem:
  sched_fork() has always called scheduler_tick() in some (unlikely)
  circumstances in order to update the current task in light of those
  circumstances.  It has always been the case that the work done by
  scheduler_tick() was more than was required to handle the problem in
  hand but no harm was done except for the waste of a few CPU cycles.

  However, the splitting of scheduler_tick() into two procedures in
  2.6.20-rc1 enables the wasted cycles to be saved as the new procedure
  task_running_tick() does all the work that is required to rectify the
  problem being handled.

Solution:
  Replace the call to scheduler_tick() in sched_fork() with a call to
  task_running_tick().

Signed-off-by: Peter Williams <pwil3058@bigpond.com.au>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-21 00:11:51 -08:00
Ingo Molnar 3117df0453 [PATCH] lockdep: print irq-trace info on asserts
When we print an assert due to scheduling-in-atomic bugs, and if lockdep
is enabled, then the IRQ tracing information of lockdep can be printed
to pinpoint the code location that disabled interrupts. This saved me
quite a bit of debugging time in cases where the backtrace did not
identify the irq-disabling site well enough.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-13 09:05:50 -08:00
Miguel Ojeda Sandonis 33859f7f97 [PATCH] kernel/sched.c: whitespace cleanups
[akpm@osdl.org: additional cleanups]
Signed-off-by: Miguel Ojeda Sandonis <maxextreme@gmail.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-10 09:57:20 -08:00
Chen, Kenneth W 62ab616d54 [PATCH] sched: optimize activate_task for RT task
RT task does not participate in interactiveness priority and thus shouldn't
be bothered with timestamp and p->sleep_type manipulation when task is
being put on run queue.  Bypass all of the them with a single if (rt_task)
test.

Signed-off-by: Ken Chen <kenneth.w.chen@intel.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: "Siddha, Suresh B" <suresh.b.siddha@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-10 09:55:43 -08:00
Chen, Kenneth W 06066714f6 [PATCH] sched: remove lb_stopbalance counter
Remove scheduler stats lb_stopbalance counter.  This counter can be
calculated by: lb_balanced - lb_nobusyg - lb_nobusyq.  There is no need to
create gazillion counters while we can derive the value.

Signed-off-by: Ken Chen <kenneth.w.chen@intel.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-10 09:55:43 -08:00
Siddha, Suresh B 783609c6cb [PATCH] sched: decrease number of load balances
Currently at a particular domain, each cpu in the sched group will do a
load balance at the frequency of balance_interval.  More the cores and
threads, more the cpus will be in each sched group at SMP and NUMA domain.
And we endup spending quite a bit of time doing load balancing in those
domains.

Fix this by making only one cpu(first idle cpu or first cpu in the group if
all the cpus are busy) in the sched group do the load balance at that
particular sched domain and this load will slowly percolate down to the
other cpus with in that group(when they do load balancing at lower
domains).

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Christoph Lameter <clameter@engr.sgi.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-10 09:55:43 -08:00
Mike Galbraith b18ec80396 [PATCH] sched: improve migration accuracy
Co-opt rq->timestamp_last_tick to maintain a cache_hot_time evaluation
reference timestamp at both tick and sched times to prevent said reference,
formerly rq->timestamp_last_tick, from being behind task->last_ran at
evaluation time, and to move said reference closer to current time on the
remote processor, intent being to improve cache hot evaluation and
timestamp adjustment accuracy for task migration.

Fix minor sched_time double accounting error which occurs when a task
passing through schedule() does not schedule off, and takes the next timer
tick.

[kenneth.w.chen@intel.com: cleanup]
Signed-off-by: Mike Galbraith <efault@gmx.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Ken Chen <kenneth.w.chen@intel.com>
Cc: Don Mullis <dwm@meer.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-10 09:55:43 -08:00
Christoph Lameter 08c183f31b [PATCH] sched: add option to serialize load balancing
Large sched domains can be very expensive to scan.  Add an option SD_SERIALIZE
to the sched domain flags.  If that flag is set then we make sure that no
other such domain is being balanced.

[akpm@osdl.org: build fix]
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Peter Williams <pwil3058@bigpond.net.au>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: "Siddha, Suresh B" <suresh.b.siddha@intel.com>
Cc: "Chen, Kenneth W" <kenneth.w.chen@intel.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-10 09:55:43 -08:00
Christoph Lameter 1bd77f2da5 [PATCH] sched: call tasklet less frequently
Trigger softirq less frequently

We trigger the softirq before this patch using offset of sd->interval.
However, if the queue is busy then it is sufficient to schedule the softirq
with sd->interval * busy_factor.

So we modify the calculation of the next time to balance by taking
the interval added to last_balance again. This is only the
right value if the idle/busy situation continues as is.

There are two potential trouble spots:
- If the queue was idle and now gets busy then we call rebalance
  early. However, that is not a problem because we will then use
  the longer interval for the next period.

- If the queue was busy and becomes idle then we potentially
  wait too long before rebalancing. However, when the task
  goes idle then idle_balance is called. We add another calculation
  of the next balance time based on sd->interval in idle_balance
  so that we will rebalance soon.

V2->V3:
- Calculate rebalance time based on current jiffies and not
  based on the jiffies at the last time we load balanced.
  We no longer rely on staggering and therefore we can
  affort to do this now.

V3->V4:
- Use functions to do jiffy comparisons.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Peter Williams <pwil3058@bigpond.net.au>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: "Siddha, Suresh B" <suresh.b.siddha@intel.com>
Cc: "Chen, Kenneth W" <kenneth.w.chen@intel.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-10 09:55:43 -08:00
Christoph Lameter c9819f4593 [PATCH] sched: use softirq for load balancing
Call rebalance_tick (renamed to run_rebalance_domains) from a newly introduced
softirq.

We calculate the earliest time for each layer of sched domains to be rescanned
(this is the rescan time for idle) and use the earliest of those to schedule
the softirq via a new field "next_balance" added to struct rq.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Peter Williams <pwil3058@bigpond.net.au>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: "Siddha, Suresh B" <suresh.b.siddha@intel.com>
Cc: "Chen, Kenneth W" <kenneth.w.chen@intel.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-10 09:55:42 -08:00
Christoph Lameter e418e1c2bf [PATCH] sched: move idle status calculation into rebalance_tick()
Perform the idle state determination in rebalance_tick.

If we separate balancing from sched_tick then we also need to determine the
idle state in rebalance_tick.

V2->V3
	Remove useless idlle != 0 check. Checking nr_running seems
	to be sufficient. Thanks Suresh.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Peter Williams <pwil3058@bigpond.net.au>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: "Siddha, Suresh B" <suresh.b.siddha@intel.com>
Cc: "Chen, Kenneth W" <kenneth.w.chen@intel.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-10 09:55:42 -08:00
Christoph Lameter 7835b98bc6 [PATCH] sched: extract load calculation from rebalance_tick
A load calculation is always done in rebalance_tick() in addition to the real
load balancing activities that only take place when certain jiffie counts have
been reached.  Move that processing into a separate function and call it
directly from scheduler_tick().

Also extract the time slice handling from scheduler_tick and put it into a
separate function.  Then we can clean up scheduler_tick significantly.  It
will no longer have any gotos.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Peter Williams <pwil3058@bigpond.net.au>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: "Siddha, Suresh B" <suresh.b.siddha@intel.com>
Cc: "Chen, Kenneth W" <kenneth.w.chen@intel.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-10 09:55:42 -08:00
Christoph Lameter fe2eea3faf [PATCH] sched: disable interrupts for locking in load_balance()
Interrupts must be disabled for request queue locks if we want to run
load_balance() with interrupts enabled.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Peter Williams <pwil3058@bigpond.net.au>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: "Siddha, Suresh B" <suresh.b.siddha@intel.com>
Cc: "Chen, Kenneth W" <kenneth.w.chen@intel.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-10 09:55:42 -08:00
Christoph Lameter 4211a9a2e9 [PATCH] sched: remove staggering of load balancing
Timer interrupts already are staggered.  We do not need an additional layer of
time staggering for short load balancing actions that take a reasonably small
portion of the time slice.

For load balancing on large sched_domains we will add a serialization later
that avoids concurrent load balance operations and thus has the same effect as
load staggering.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Peter Williams <pwil3058@bigpond.net.au>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: "Siddha, Suresh B" <suresh.b.siddha@intel.com>
Cc: "Chen, Kenneth W" <kenneth.w.chen@intel.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-10 09:55:42 -08:00
Christoph Lameter 571f6d2fb0 [PATCH] sched: avoid taking rq lock in wake_priority_sleeper
Avoid taking the request queue lock in wake_priority_sleeper if there are no
running processes.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Peter Williams <pwil3058@bigpond.net.au>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: "Siddha, Suresh B" <suresh.b.siddha@intel.com>
Cc: "Chen, Kenneth W" <kenneth.w.chen@intel.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-10 09:55:42 -08:00
Kirill Korotaev 054b9108e0 [PATCH] move_task_off_dead_cpu() should be called with disabled ints
move_task_off_dead_cpu() requires interrupts to be disabled, while
migrate_dead() calls it with enabled interrupts.  Added appropriate
comments to functions and added BUG_ON(!irqs_disabled()) into
double_rq_lock() and double_lock_balance() which are the origin sources of
such bugs.

Signed-off-by: Kirill Korotaev <dev@openvz.org>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-10 09:55:42 -08:00
Siddha, Suresh B 6711cab43e [PATCH] ched domain: move sched group allocations to percpu area
Move the sched group allocations to percpu area.  This will minimize cross
node memory references and also cleans up the sched groups allocation for
allnodes sched domain.

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-10 09:55:42 -08:00
Robert P. J. Day cc2a73b5ca [PATCH] sched.c: correct comment for this_rq_lock()
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Robert P. J. Day <rpjday@mindspring.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-10 09:55:42 -08:00
Helge Deller 15ad7cdcfd [PATCH] struct seq_operations and struct file_operations constification
- move some file_operations structs into the .rodata section

 - move static strings from policy_types[] array into the .rodata section

 - fix generic seq_operations usages, so that those structs may be defined
   as "const" as well

[akpm@osdl.org: couple of fixes]
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-07 08:39:46 -08:00
Chris Caputo 301827acbe [PATCH] sched: correct output of show_state()
At present show_state prints a header the does not match the output of
show_task, as follows:

-
                                               sibling
  task             PC      pid father child younger older
init          S 00000000     0     1      0     2               (NOTLB)
-

This patch corrects the output of show_state so that the header is
aligned with the data, ala:

-
                         free                        sibling
  task             PC    stack   pid father child younger older
init          S 00000000     0     1      0     2               (NOTLB)
-

Signed-off-by: Chris Caputo <ccaputo@alt.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-07 08:39:42 -08:00
Ingo Molnar 0231606785 [PATCH] hotplug CPU: clean up hotcpu_notifier() use
There was lots of #ifdef noise in the kernel due to hotcpu_notifier(fn,
prio) not correctly marking 'fn' as used in the !HOTPLUG_CPU case, and thus
generating compiler warnings of unused symbols, hence forcing people to add
#ifdefs.

the compiler can skip truly unused functions just fine:

    text    data     bss     dec     hex filename
 1624412  728710 3674856 6027978  5bfaca vmlinux.before
 1624412  728710 3674856 6027978  5bfaca vmlinux.after

[akpm@osdl.org: topology.c fix]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-07 08:39:39 -08:00
Ingo Molnar ece8a684c7 [PATCH] sleep profiling
Implement prof=sleep profiling.  TASK_UNINTERRUPTIBLE sleeps will be taken
as a profile hit, and every millisecond spent sleeping causes a profile-hit
for the call site that initiated the sleep.

Sample readprofile output on i386:

   306 ps2_sendbyte                               1.3973
   432 call_usermodehelper_keys                   1.9548
   484 ps2_command                                0.6453
   790 __driver_attach                            4.7879
  1593 msleep                                    44.2500
  3976 sync_buffer                               64.1290
  4076 do_lookup                                 12.4648
  8587 sync_page                                122.6714
 20820 total                                      0.0067

(NOTE: architectures need to check whether get_wchan() can be called from
deep within the wakeup path.)

akpm: we need to mark more functions __sched.  lock_sock(), msleep(), others..

akpm: the contention in do_lookup() is a surprise.  Presumably doing disk
reads for directory contents while holding i_mutex.

[akpm@osdl.org: various fixes]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-07 08:39:36 -08:00
Peter Zijlstra a4c410f00f [PATCH] lockdep: print current locks on in_atomic warnings
Add debug_show_held_locks(current) to __might_sleep() and schedule(); this
makes finding the offending lock leak easier.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-07 08:39:36 -08:00
Ingo Molnar e59e2ae2c2 [PATCH] SysRq-X: show blocked tasks
Add SysRq-X support: show blocked (TASK_UNINTERRUPTIBLE) tasks only.

Useful for debugging IO stalls.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-07 08:39:32 -08:00
Nigel Cunningham 7dfb71030f [PATCH] Add include/linux/freezer.h and move definitions from sched.h
Move process freezing functions from include/linux/sched.h to freezer.h, so
that modifications to the freezer or the kernel configuration don't require
recompiling just about everything.

[akpm@osdl.org: fix ueagle driver]
Signed-off-by: Nigel Cunningham <nigel@suspend2.net>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-07 08:39:27 -08:00