percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files. percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.
percpu.h -> slab.h dependency is about to be removed. Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability. As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.
http://userweb.kernel.org/~tj/misc/slabh-sweep.py
The script does the followings.
* Scan files for gfp and slab usages and update includes such that
only the necessary includes are there. ie. if only gfp is used,
gfp.h, if slab is used, slab.h.
* When the script inserts a new include, it looks at the include
blocks and try to put the new include such that its order conforms
to its surrounding. It's put in the include block which contains
core kernel includes, in the same order that the rest are ordered -
alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
doesn't seem to be any matching order.
* If the script can't find a place to put a new include (mostly
because the file doesn't have fitting include block), it prints out
an error message indicating which .h file needs to be added to the
file.
The conversion was done in the following steps.
1. The initial automatic conversion of all .c files updated slightly
over 4000 files, deleting around 700 includes and adding ~480 gfp.h
and ~3000 slab.h inclusions. The script emitted errors for ~400
files.
2. Each error was manually checked. Some didn't need the inclusion,
some needed manual addition while adding it to implementation .h or
embedding .c file was more appropriate for others. This step added
inclusions to around 150 files.
3. The script was run again and the output was compared to the edits
from #2 to make sure no file was left behind.
4. Several build tests were done and a couple of problems were fixed.
e.g. lib/decompress_*.c used malloc/free() wrappers around slab
APIs requiring slab.h to be added manually.
5. The script was run on all .h files but without automatically
editing them as sprinkling gfp.h and slab.h inclusions around .h
files could easily lead to inclusion dependency hell. Most gfp.h
inclusion directives were ignored as stuff from gfp.h was usually
wildly available and often used in preprocessor macros. Each
slab.h inclusion directive was examined and added manually as
necessary.
6. percpu.h was updated not to include slab.h.
7. Build test were done on the following configurations and failures
were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my
distributed build env didn't work with gcov compiles) and a few
more options had to be turned off depending on archs to make things
build (like ipr on powerpc/64 which failed due to missing writeq).
* x86 and x86_64 UP and SMP allmodconfig and a custom test config.
* powerpc and powerpc64 SMP allmodconfig
* sparc and sparc64 SMP allmodconfig
* ia64 SMP allmodconfig
* s390 SMP allmodconfig
* alpha SMP allmodconfig
* um on x86_64 SMP allmodconfig
8. percpu.h modifications were reverted so that it could be applied as
a separate patch and serve as bisection point.
Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.
Signed-off-by: Tejun Heo <tj@kernel.org>
Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
Support for the PMU's BTS features has been upstreamed in
v2.6.32, but we still have the old and disabled ptrace-BTS,
as Linus noticed it not so long ago.
It's buggy: TIF_DEBUGCTLMSR is trampling all over that MSR without
regard for other uses (perf) and doesn't provide the flexibility
needed for perf either.
Its users are ptrace-block-step and ptrace-bts, since ptrace-bts
was never used and ptrace-block-step can be implemented using a
much simpler approach.
So axe all 3000 lines of it. That includes the *locked_memory*()
APIs in mm/mlock.c as well.
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Roland McGrath <roland@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Markus Metzger <markus.t.metzger@intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
LKML-Reference: <20100325135413.938004390@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
On UP:
kernel/sched.c: In function 'wake_up_new_task':
kernel/sched.c:2631: warning: unused variable 'cpu'
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
[ Note, this commit changes the syscall ABI for > 1024 CPUs systems. ]
Recently, some distro decided to use NR_CPUS=4096 for mysterious reasons.
Unfortunately, glibc sched interface has the following definition:
# define __CPU_SETSIZE 1024
# define __NCPUBITS (8 * sizeof (__cpu_mask))
typedef unsigned long int __cpu_mask;
typedef struct
{
__cpu_mask __bits[__CPU_SETSIZE / __NCPUBITS];
} cpu_set_t;
It mean, if NR_CPUS is bigger than 1024, cpu_set_t makes an
ABI issue ...
More recently, Sharyathi Nagesh reported following test program makes
misterious syscall failure:
-----------------------------------------------------------------------
#define _GNU_SOURCE
#include<stdio.h>
#include<errno.h>
#include<sched.h>
int main()
{
cpu_set_t set;
if (sched_getaffinity(0, sizeof(cpu_set_t), &set) < 0)
printf("\n Call is failing with:%d", errno);
}
-----------------------------------------------------------------------
Because the kernel assumes len argument of sched_getaffinity() is bigger
than NR_CPUS. But now it is not correct.
Now we are faced with the following annoying dilemma, due to
the limitations of the glibc interface built in years ago:
(1) if we change glibc's __CPU_SETSIZE definition, we lost
binary compatibility of _all_ application.
(2) if we don't change it, we also lost binary compatibility of
Sharyathi's use case.
Then, I would propse to change the rule of the len argument of
sched_getaffinity().
Old:
len should be bigger than NR_CPUS
New:
len should be bigger than maximum possible cpu id
This creates the following behavior:
(A) In the real 4096 cpus machine, the above test program still
return -EINVAL.
(B) NR_CPUS=4096 but the machine have less than 1024 cpus (almost
all machines in the world), the above can run successfully.
Fortunatelly, BIG SGI machine is mainly used for HPC use case. It means
they can rebuild their programs.
IOW we hope they are not annoyed by this issue ...
Reported-by: Sharyathi Nagesh <sharyath@in.ibm.com>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: Ulrich Drepper <drepper@redhat.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jack Steiner <steiner@sgi.com>
Cc: Russ Anderson <rja@sgi.com>
Cc: Mike Travis <travis@sgi.com>
LKML-Reference: <20100312161316.9520.A69D9226@jp.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
* 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
sched: Fix pick_next_highest_task_rt() for cgroups
sched: Cleanup: remove unused variable in try_to_wake_up()
x86: Fix sched_clock_cpu for systems with unsynchronized TSC
Sync wakeups are critical functionality with a long history. Remove it, we don't
need the branch or icache footprint.
Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1268301817.6785.47.camel@marge.simson.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Now that we no longer depend on the clock being updated prior to enqueueing
on migratory wakeup, we can clean up a bit, placing calls to update_rq_clock()
exactly where they are needed, ie on enqueue, dequeue and schedule events.
In the case of a freshly enqueued task immediately preempting, we can skip the
update during preemption, as the clock was just updated by the enqueue event.
We also save an unneeded call during a migratory wakeup by not updating the
previous runqueue, where update_curr() won't be invoked.
Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1268301199.6785.32.camel@marge.simson.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Both avg_overlap and avg_wakeup had an inherent problem in that their accuracy
was detrimentally affected by cross-cpu wakeups, this because we are missing
the necessary call to update_curr(). This can't be fixed without increasing
overhead in our already too fat fastpath.
Additionally, with recent load balancing changes making us prefer to place tasks
in an idle cache domain (which is good for compute bound loads), communicating
tasks suffer when a sync wakeup, which would enable affine placement, is turned
into a non-sync wakeup by SYNC_LESS. With one task on the runqueue, wake_affine()
rejects the affine wakeup request, leaving the unfortunate where placed, taking
frequent cache misses.
Remove it, and recover some fastpath cycles.
Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1268301121.6785.30.camel@marge.simson.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Testing the load which led to this heuristic (nfs4 kbuild) shows that it has
outlived it's usefullness. With intervening load balancing changes, I cannot
see any difference with/without, so recover there fastpath cycles.
Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1268301062.6785.29.camel@marge.simson.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Entering nohz code on every micro-idle is costing ~10% throughput for netperf
TCP_RR when scheduling cross-cpu. Rate limiting entry fixes this, but raises
ticks a bit. On my Q6600, an idle box goes from ~85 interrupts/sec to 128.
The higher the context switch rate, the more nohz entry costs. With this patch
and some cycle recovery patches in my tree, max cross cpu context switch rate is
improved by ~16%, a large portion of which of which is this ratelimiting.
Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1268301003.6785.28.camel@marge.simson.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Put all statistic fields of sched_entity in one struct, sched_statistics,
and embed it into sched_entity.
This change allows to memset the sched_statistics to 0 when needed (for
instance when forking), avoiding bugs of non initialized fields.
Signed-off-by: Lucas De Marchi <lucas.de.marchi@gmail.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1268275065-18542-1-git-send-email-lucas.de.marchi@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
We haven't used the "orig_rq" variable since
055a00865d "Fix/add missing update_rq_clock() calls"
Signed-off-by: Dan Carpenter <error27@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andreas Herrmann <andreas.herrmann3@amd.com>
Cc: Gautham R Shenoy <ego@in.ibm.com>
Cc: efault@gmx.de
LKML-Reference: <20100306111752.GL4958@bicker>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Passing the attribute to the low level IO functions allows all kinds
of cleanups, by sharing low level IO code without requiring
an own function for every piece of data.
Also drivers can extend the attributes with own data fields
and use that in the low level function.
Similar to sysdev_attributes and normal attributes.
This is a tree-wide sweep, converting everything in one go.
No functional changes in this patch other than passing the new
argument everywhere.
Tested on x86, the non x86 parts are uncompiled.
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Make sure compiler won't do weird things with limits. E.g. fetching them
twice may return 2 different values after writable limits are implemented.
I.e. either use rlimit helpers added in commit 3e10e716ab ("resource:
add helpers for fetching rlimits") or ACCESS_ONCE if not applicable.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: john stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (25 commits)
sched: Fix SCHED_MC regression caused by change in sched cpu_power
sched: Don't use possibly stale sched_class
kthread, sched: Remove reference to kthread_create_on_cpu
sched: cpuacct: Use bigger percpu counter batch values for stats counters
percpu_counter: Make __percpu_counter_add an inline function on UP
sched: Remove member rt_se from struct rt_rq
sched: Change usage of rt_rq->rt_se to rt_rq->tg->rt_se[cpu]
sched: Remove unused update_shares_locked()
sched: Use for_each_bit
sched: Queue a deboosted task to the head of the RT prio queue
sched: Implement head queueing for sched_rt
sched: Extend enqueue_task to allow head queueing
sched: Remove USER_SCHED
sched: Fix the place where group powers are updated
sched: Assume *balance is valid
sched: Remove load_balance_newidle()
sched: Unify load_balance{,_newidle}()
sched: Add a lock break for PREEMPT=y
sched: Remove from fwd decls
sched: Remove rq_iterator from move_one_task
...
Fix up trivial conflicts in kernel/sched.c
* 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
sched: Fix race between ttwu() and task_rq_lock()
sched: Fix SMT scheduler regression in find_busiest_queue()
sched: Fix sched_mv_power_savings for !SMT
kernel/sched.c: Suppress unused var warning
setscheduler() saves task->sched_class outside of the rq->lock held
region for a check after the setscheduler changes have become
effective. That might result in checking a stale value.
rtmutex_setprio() has the same problem, though it is protected by
p->pi_lock against setscheduler(), but for correctness sake (and to
avoid bad examples) it needs to be fixed as well.
Retrieve task->sched_class inside of the rq->lock held region.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: stable@kernel.org
Add __percpu sparse annotations to core subsystems.
These annotations are to make sparse consider percpu variables to be
in a different address space and warn if accessed without going
through percpu accessors. This patch doesn't affect normal builds.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Christoph Lameter <cl@linux-foundation.org>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: linux-mm@kvack.org
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Dipankar Sarma <dipankar@in.ibm.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Eric Biederman <ebiederm@xmission.com>
Conflicts: kernel/sched.c
Necessary due to the urgent fixes which conflict with the code move
from sched.c to sched_fair.c
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Thomas found that due to ttwu() changing a task's cpu without holding
the rq->lock, task_rq_lock() might end up locking the wrong rq.
Avoid this by serializing against TASK_WAKING.
Reported-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1266241712.15770.420.camel@laptop>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Fix a SMT scheduler performance regression that is leading to a scenario
where SMT threads in one core are completely idle while both the SMT threads
in another core (on the same socket) are busy.
This is caused by this commit (with the problematic code highlighted)
commit bdb94aa5db
Author: Peter Zijlstra <a.p.zijlstra@chello.nl>
Date: Tue Sep 1 10:34:38 2009 +0200
sched: Try to deal with low capacity
@@ -4203,15 +4223,18 @@ find_busiest_queue()
...
for_each_cpu(i, sched_group_cpus(group)) {
+ unsigned long power = power_of(i);
...
- wl = weighted_cpuload(i);
+ wl = weighted_cpuload(i) * SCHED_LOAD_SCALE;
+ wl /= power;
- if (rq->nr_running == 1 && wl > imbalance)
+ if (capacity && rq->nr_running == 1 && wl > imbalance)
continue;
On a SMT system, power of the HT logical cpu will be 589 and
the scheduler load imbalance (for scenarios like the one mentioned above)
can be approximately 1024 (SCHED_LOAD_SCALE). The above change of scaling
the weighted load with the power will result in "wl > imbalance" and
ultimately resulting in find_busiest_queue() return NULL, causing
load_balance() to think that the load is well balanced. But infact
one of the tasks can be moved to the idle core for optimal performance.
We don't need to use the weighted load (wl) scaled by the cpu power to
compare with imabalance. In that condition, we already know there is only a
single task "rq->nr_running == 1" and the comparison between imbalance,
wl is to make sure that we select the correct priority thread which matches
imbalance. So we really need to compare the imabalnce with the original
weighted load of the cpu and not the scaled load.
But in other conditions where we want the most hammered(busiest) cpu, we can
use scaled load to ensure that we consider the cpu power in addition to the
actual load on that cpu, so that we can move the load away from the
guy that is getting most hammered with respect to the actual capacity,
as compared with the rest of the cpu's in that busiest group.
Fix it.
Reported-by: Ma Ling <ling.ma@intel.com>
Initial-Analysis-by: Zhang, Yanmin <yanmin_zhang@linux.intel.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1266023662.2808.118.camel@sbs-t61.sc.intel.com>
Cc: stable@kernel.org [2.6.32.x]
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
When CONFIG_VIRT_CPU_ACCOUNTING and CONFIG_CGROUP_CPUACCT are
enabled we can call cpuacct_update_stats with values much larger
than percpu_counter_batch. This means the call to
percpu_counter_add will always add to the global count which is
protected by a spinlock and we end up with a global spinlock in
the scheduler.
Based on an idea by KOSAKI Motohiro, this patch scales the batch
value by cputime_one_jiffy such that we have the same batch
limit as we would if CONFIG_VIRT_CPU_ACCOUNTING was disabled.
His patch did this once at boot but that initialisation happened
too early on PowerPC (before time_init) and it was never updated
at runtime as a result of a hotplug cpu add/remove.
This patch instead scales percpu_counter_batch by
cputime_one_jiffy at runtime, which keeps the batch correct even
after cpu hotplug operations. We cap it at INT_MAX in case of
overflow.
For architectures that do not support
CONFIG_VIRT_CPU_ACCOUNTING, cputime_one_jiffy is the constant 1
and gcc is smart enough to optimise min(s32
percpu_counter_batch, INT_MAX) to just percpu_counter_batch at
least on x86 and PowerPC. So there is no need to add an #ifdef.
On a 64 thread PowerPC box with CONFIG_VIRT_CPU_ACCOUNTING and
CONFIG_CGROUP_CPUACCT enabled, a context switch microbenchmark
is 234x faster and almost matches a CONFIG_CGROUP_CPUACCT
disabled kernel:
CONFIG_CGROUP_CPUACCT disabled: 16906698 ctx switches/sec
CONFIG_CGROUP_CPUACCT enabled: 61720 ctx switches/sec
CONFIG_CGROUP_CPUACCT + patch: 16663217 ctx switches/sec
Tested with:
wget http://ozlabs.org/~anton/junkcode/context_switch.c
make context_switch
for i in `seq 0 63`; do taskset -c $i ./context_switch & done
vmstat 1
Signed-off-by: Anton Blanchard <anton@samba.org>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Tested-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
On UP:
kernel/sched.c: In function 'wake_up_new_task':
kernel/sched.c:2631: warning: unused variable 'cpu'
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
It's a duplicate of tg->rt_se[cpu] and the only usage is
sched_rt_rq_dequeue() and sched_rt_rq_enqueue(). After the
first patch to those two function. rt_se can be removed.
Signed-off-by: Yong Zhang <yong.zhang0@gmail.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <2674af741001282258q38781619u653ca4a7dd267347@mail.gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Commit f492e12ef0 ("sched: Remove
load_balance_newidle()") removed the only user of this function,
so remove it too.
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1265019219.24455.128.camel@laptop>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
rtmutex_set_prio() is used to implement priority inheritance for
futexes. When a task is deboosted it gets enqueued at the tail of its
RT priority list. This is violating the POSIX scheduling semantics:
rt priority list X contains two runnable tasks A and B
task A runs with priority X and holds mutex M
task C preempts A and is blocked on mutex M
-> task A is boosted to priority of task C (Y)
task A unlocks the mutex M and deboosts itself
-> A is dequeued from rt priority list Y
-> A is enqueued to the tail of rt priority list X
task C schedules away
task B runs
This is wrong as task A did not schedule away and therefor violates
the POSIX scheduling semantics.
Enqueue the task to the head of the priority list instead.
Reported-by: Mathias Weber <mathias.weber.mw1@roche.com>
Reported-by: Carsten Emde <cbe@osadl.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Tested-by: Carsten Emde <cbe@osadl.org>
Tested-by: Mathias Weber <mathias.weber.mw1@roche.com>
LKML-Reference: <20100120171629.809074113@linutronix.de>
The ability of enqueueing a task to the head of a SCHED_FIFO priority
list is required to fix some violations of POSIX scheduling policy.
Extend the related functions with a "head" argument.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Tested-by: Carsten Emde <cbe@osadl.org>
Tested-by: Mathias Weber <mathias.weber.mw1@roche.com>
LKML-Reference: <20100120171629.734886007@linutronix.de>
There are a number of issues:
1) TASK_WAKING vs cgroup_clone (cpusets)
copy_process():
sched_fork()
child->state = TASK_WAKING; /* waiting for wake_up_new_task() */
if (current->nsproxy != p->nsproxy)
ns_cgroup_clone()
cgroup_clone()
mutex_lock(inode->i_mutex)
mutex_lock(cgroup_mutex)
cgroup_attach_task()
ss->can_attach()
ss->attach() [ -> cpuset_attach() ]
cpuset_attach_task()
set_cpus_allowed_ptr();
while (child->state == TASK_WAKING)
cpu_relax();
will deadlock the system.
2) cgroup_clone (cpusets) vs copy_process
So even if the above would work we still have:
copy_process():
if (current->nsproxy != p->nsproxy)
ns_cgroup_clone()
cgroup_clone()
mutex_lock(inode->i_mutex)
mutex_lock(cgroup_mutex)
cgroup_attach_task()
ss->can_attach()
ss->attach() [ -> cpuset_attach() ]
cpuset_attach_task()
set_cpus_allowed_ptr();
...
p->cpus_allowed = current->cpus_allowed
over-writing the modified cpus_allowed.
3) fork() vs hotplug
if we unplug the child's cpu after the sanity check when the child
gets attached to the task_list but before wake_up_new_task() shit
will meet with fan.
Solve all these issues by moving fork cpu selection into
wake_up_new_task().
Reported-by: Serge E. Hallyn <serue@us.ibm.com>
Tested-by: Serge E. Hallyn <serue@us.ibm.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1264106190.4283.1314.camel@laptop>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Remove the USER_SCHED feature. It has been scheduled to be removed in
2.6.34 as per http://marc.info/?l=linux-kernel&m=125728479022976&w=2
Signed-off-by: Dhaval Giani <dhaval.giani@gmail.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1263990378.24844.3.camel@localhost>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Take out the sched_class methods for load-balancing.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Straight fwd code movement.
Since non of the load-balance abstractions are used anymore, do away with
them and simplify the code some. In preparation move the code around.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Assume A->B schedule is processing, if B have acquired BKL before and it
need reschedule this time. Then on B's context, it will go to
need_resched_nonpreemptible for reschedule. But at this time, prev and
switch_count are related to A. It's wrong and will lead to incorrect
scheduler statistics.
Signed-off-by: Yong Zhang <yong.zhang0@gmail.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <2674af741001102238w7b0ddcadref00d345e2181d11@mail.gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
perf_event_task_sched_in() expects interrupts to be disabled,
but on architectures with __ARCH_WANT_INTERRUPTS_ON_CTXSW
defined, this isn't true. If this is defined, disable irqs
around the call in finish_task_switch().
Signed-off-by: Jamie Iles <jamie.iles@picochip.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King - ARM Linux <linux@arm.linux.org.uk>
LKML-Reference: <1262964453-27370-1-git-send-email-jamie.iles@picochip.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Fixes a warning when building with g++:
warning: deprecated conversion from string constant to 'char*'
And the file parameter use is constant, so mark it as such.
Signed-off-by: Simon Kagstrom <simon.kagstrom@netinsight.net>
Cc: peterz@infradead.org
LKML-Reference: <20091223110818.442d848e@marrow.netinsight.se>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Since we only ever schedule the local cpu, there is no need to pass the
cpu number to the perf sched hooks.
This micro-optimizes things a bit.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Effectively reverts 738d2be430.
As demonstrated by Eric, we really need to call __set_task_cpu()
early in the fork() path to properly initialize the various task
state -- specifically the cgroup state through set_task_rq().
[ we could probably fix this by explicitly calling
__set_task_cpu() from sched_fork(), but lets try that for the
next cycle and simply revert to the old behaviour for now. ]
Reported-by: Eric Paris <eparis@redhat.com>
Tested-by: Eric Paris <eparis@redhat.com>,
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: efault@gmx.de
LKML-Reference: <1261492999.4937.36.camel@laptop>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
The hot-unplug kstopmachine usage does a wakeup after
deactivating the cpu, hence we cannot use cpu_active()
here but must rely on the good olde online.
Reported-by: Sachin Sant <sachinp@in.ibm.com>
Reported-by: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Tested-by: Jens Axboe <jens.axboe@oracle.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
LKML-Reference: <1261326987.4314.24.camel@laptop>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Revert the braindead pr_* crap. (Commit 663997d "sched: Use
pr_fmt() and pr_<level>()")
It's dumb and causes stupid "sched: " strings all over the place.
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Mike Galbraith <efault@gmx.de>
Cc: Joe Perches <joe@perches.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
LKML-Reference: <1261315437.4314.6.camel@laptop>
[ i dont mind the pr_*() patterns that much - but Peter dislikes them with a vengence. ]
[ - v2: remove spurious diffstat from changelog :-/ ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
There's a preemption race in the set_task_cpu() debug check in
that when we get preempted after setting task->state we'd still
be on the rq proper, but fail the test.
Check for preempted tasks, since those are always on the RQ.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20091217121830.137155561@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
In practice, it is harmless to voluntarily sleep in a
rcu_read_lock() section if we are running under preempt rcu, but
it is illegal if we build a kernel running non-preemptable rcu.
Currently, might_sleep() doesn't notice sleepable operations
under rcu_read_lock() sections if we are running under
preemptable rcu because preempt_count() is left untouched after
rcu_read_lock() in this case. But we want developers who test
their changes under such config to notice the "sleeping while
atomic" issues.
So we add rcu_read_lock_nesting to prempt_count() in
might_sleep() checks.
[ v2: Handle rcu-tiny ]
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <1260991265-8451-1-git-send-regression-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Rearrange code a bit now that its a simpler function.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
LKML-Reference: <20091216170518.269101883@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
In order to remove the cfs_rq dependency from set_task_cpu() we
need to ensure the task is cfs_rq invariant for all callsites.
The simple approach is to substract cfs_rq->min_vruntime from
se->vruntime on dequeue, and add cfs_rq->min_vruntime on
enqueue.
However, this has the downside of breaking FAIR_SLEEPERS since
we loose the old vruntime as we only maintain the relative
position.
To solve this, we observe that we only migrate runnable tasks,
we do this using deactivate_task(.sleep=0) and
activate_task(.wakeup=0), therefore we can restrain the
min_vruntime invariance to that state.
The only other case is wakeup balancing, since we want to
maintain the old vruntime we cannot make it relative on dequeue,
but since we don't migrate inactive tasks, we can do so right
before we activate it again.
This is where we need the new pre-wakeup hook, we need to call
this while still holding the old rq->lock. We could fold it into
->select_task_rq(), but since that has multiple callsites and
would obfuscate the locking requirements, that seems like a
fudge.
This leaves the fork() case, simply make sure that ->task_fork()
leaves the ->vruntime in a relative state.
This covers all cases where set_task_cpu() gets called, and
ensures it sees a relative vruntime.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
LKML-Reference: <20091216170518.191697025@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
As will be apparent in the next patch, we need a pre wakeup hook
for sched_fair task migration, hence rename the post wakeup hook
and one pre wakeup.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
LKML-Reference: <20091216170518.114746117@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Since kthread_bind() lost its dependencies on sched.c, move it
back where it came from.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
LKML-Reference: <20091216170518.039524041@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Since select_task_rq() is now responsible for guaranteeing
->cpus_allowed and cpu_active_mask, we need to verify this.
select_task_rq_rt() can blindly return
smp_processor_id()/task_cpu() without checking the valid masks,
select_task_rq_fair() can do the same in the rare case that all
SD_flags are disabled.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
LKML-Reference: <20091216170517.961475466@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Since we access ->cpus_allowed without holding rq->lock we need
a retry loop to validate the result, this comes for near free
when we merge sched_migrate_task() into sched_exec() since that
already does the needed check.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
LKML-Reference: <20091216170517.884743662@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
In order to clean up the set_task_cpu() rq dependencies we need
to ensure it is never called on blocked tasks because such usage
does not pair with consistent rq->lock usage.
This puts the migration burden on ttwu().
Furthermore we need to close a race against changing
->cpus_allowed, since select_task_rq() runs with only preemption
disabled.
For sched_fork() this is safe because the child isn't in the
tasklist yet, for wakeup we fix this by synchronizing
set_cpus_allowed_ptr() against TASK_WAKING, which leaves
sched_exec to be a problem
This also closes a hole in (6ad4c1888 sched: Fix balance vs
hotplug race) where ->select_task_rq() doesn't validate the
result against the sched_domain/root_domain.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
LKML-Reference: <20091216170517.807938893@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
For later convenience use TASK_WAKING for fresh tasks.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
LKML-Reference: <20091216170517.732561278@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Make sure not to access sched_fair fields before verifying it is
indeed a sched_fair task.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
CC: stable@kernel.org
LKML-Reference: <20091216170517.577998058@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Convert locks which cannot be sleeping locks in preempt-rt to
raw_spinlocks.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Ingo Molnar <mingo@elte.hu>
Convert locks which cannot be sleeping locks in preempt-rt to
raw_spinlocks.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Ingo Molnar <mingo@elte.hu>
Convert locks which cannot be sleeping locks in preempt-rt to
raw_spinlocks.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Ingo Molnar <mingo@elte.hu>
The name space hierarchy for the internal lock functions is now a bit
backwards. raw_spin* functions map to _spin* which use __spin*, while
we would like to have _raw_spin* and __raw_spin*.
_raw_spin* is already used by lock debugging, so rename those funtions
to do_raw_spin* to free up the _raw_spin* name space.
No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Ingo Molnar <mingo@elte.hu>
Now that the raw_spin name space is freed up, we can implement
raw_spinlock and the related functions which are used to annotate the
locks which are not converted to sleeping spinlocks in preempt-rt.
A side effect is that only such locks can be used with the low level
lock fsunctions which circumvent lockdep.
For !rt spin_* functions are mapped to the raw_spin* implementations.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Ingo Molnar <mingo@elte.hu>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu: (34 commits)
m68k: rename global variable vmalloc_end to m68k_vmalloc_end
percpu: add missing per_cpu_ptr_to_phys() definition for UP
percpu: Fix kdump failure if booted with percpu_alloc=page
percpu: make misc percpu symbols unique
percpu: make percpu symbols in ia64 unique
percpu: make percpu symbols in powerpc unique
percpu: make percpu symbols in x86 unique
percpu: make percpu symbols in xen unique
percpu: make percpu symbols in cpufreq unique
percpu: make percpu symbols in oprofile unique
percpu: make percpu symbols in tracer unique
percpu: make percpu symbols under kernel/ and mm/ unique
percpu: remove some sparse warnings
percpu: make alloc_percpu() handle array types
vmalloc: fix use of non-existent percpu variable in put_cpu_var()
this_cpu: Use this_cpu_xx in trace_functions_graph.c
this_cpu: Use this_cpu_xx for ftrace
this_cpu: Use this_cpu_xx in nmi handling
this_cpu: Use this_cpu operations in RCU
this_cpu: Use this_cpu ops for VM statistics
...
Fix up trivial (famous last words) global per-cpu naming conflicts in
arch/x86/kvm/svm.c
mm/slab.c
read_lock(&tasklist_lock) does not protect
sys_sched_get_rr_param() against a concurrent update of the
policy or scheduler parameters as do_sched_scheduler() does not
take the tasklist_lock.
The access to task->sched_class->get_rr_interval is protected by
task_rq_lock(task).
Use rcu_read_lock() to protect find_task_by_vpid() and prevent
the task struct from going away.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <20091209100706.862897167@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
tasklist_lock is held read locked to protect the
find_task_by_vpid() call and to prevent the task going away.
sched_setaffinity acquires a task struct ref and drops tasklist
lock right away. The access to the cpus_allowed mask is
protected by rq->lock.
rcu_read_lock() provides the same protection here.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <20091209100706.789059966@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
read_lock(&tasklist_lock) does not protect
sys_sched_getscheduler and sys_sched_getparam() against a
concurrent update of the policy or scheduler parameters as
do_sched_setscheduler() does not take the tasklist_lock. The
accessed integers can be retrieved w/o locking and are snapshots
anyway.
Using rcu_read_lock() to protect find_task_by_vpid() and prevent
the task struct from going away is not changing the above
situation.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <20091209100706.753790977@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Alan Stern noticed that all the wakeup side (and atomic) variants of the
completion APIs should be irq safe, but the newly introduced
completion_done() and try_wait_for_completion() aren't. The use of the
irq unsafe variants in IRQ contexts can cause crashes/hangs.
Fix the problem by making them use spin_lock_irqsave() and
spin_lock_irqrestore().
Reported-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Zhang Rui <rui.zhang@intel.com>
Cc: pm list <linux-pm@lists.linux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: David Chinner <david@fromorbit.com>
Cc: Lachlan McIlroy <lachlan@sgi.com>
LKML-Reference: <200912130007.30541.rjw@sisk.pl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This build warning:
kernel/sched.c: In function 'set_task_cpu':
kernel/sched.c:2070: warning: unused variable 'old_rq'
Made me realize that the forced2_migrations stat looks pretty
pointless (and a misnomer) - remove it.
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
If the second in each of these pairs of allocations fails, then the
first one will not be freed in the error route out.
Found by a static code analysis tool.
Signed-off-by: Phil Carmody <ext-phil.2.carmody@nokia.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1260448177-28448-1-git-send-email-ext-phil.2.carmody@nokia.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
The normalized values are also recalculated in case the scaling factor
changes.
This patch updates the internally used scheduler tuning values that are
normalized to one cpu in case a user sets new values via sysfs.
Together with patch 2 of this series this allows to let user configured
values scale (or not) to cpu add/remove events taking place later.
Signed-off-by: Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1259579808-11357-4-git-send-email-ehrhardt@linux.vnet.ibm.com>
[ v2: fix warning ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
As scaling now takes place on all kind of cpu add/remove events a user
that configures values via proc should be able to configure if his set
values are still rescaled or kept whatever happens.
As the comments state that log2 was just a second guess that worked the
interface is not just designed for on/off, but to choose a scaling type.
Currently this allows none, log and linear, but more important it allwos
us to keep the interface even if someone has an even better idea how to
scale the values.
Signed-off-by: Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1259579808-11357-3-git-send-email-ehrhardt@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Based on Peter Zijlstras patch suggestion this enables recalculation of
the scheduler tunables in response of a change in the number of cpus. It
also adds a max of eight cpus that are considered in that scaling.
Signed-off-by: Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1259579808-11357-2-git-send-email-ehrhardt@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
83f9ac removed a call to effective_prio() in wake_up_new_task(), which
leads to tasks running at MAX_PRIO.
This is caused by the idle thread being set to MAX_PRIO before forking
off init. O(1) used that to make sure idle was always preempted, CFS
uses check_preempt_curr_idle() for that so we can savely remove this bit
of legacy code.
Reported-by: Mike Galbraith <efault@gmx.de>
Tested-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1259754383.4003.610.camel@laptop>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
When setting the weight for a per-cpu task-group, we have to put in a
phantom weight when there is no work on that cpu, otherwise we'll not
service that cpu when new work gets placed there until we again update
the per-cpu weights.
We used to add these phantom weights to the total, so that the idle
per-cpu shares don't get inflated, this however causes the non-idle
parts to get deflated, causing unexpected weight distibutions.
Reverse this, so that the non-idle shares are correct but the idle
shares are inflated.
Reported-by: Yasunori Goto <y-goto@jp.fujitsu.com>
Tested-by: Yasunori Goto <y-goto@jp.fujitsu.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1257934048.23203.76.camel@twins>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
WAKEUP_RUNNING was an experiment, not sure why that ever ended up being
merged...
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Currently we try to do task placement in wake_up_new_task() after we do
the load-balance pass in sched_fork(). This yields complicated semantics
in that we have to deal with tasks on different RQs and the
set_task_cpu() calls in copy_process() and sched_fork()
Rename ->task_new() to ->task_fork() and call it from sched_fork()
before the balancing, this gives the policy a clear point to place the
task.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Since set_task_clock() doesn't rely on rq->clock anymore we can simplyfy
the mess in ttwu().
Optimize things a bit by not fiddling with the IRQ state there.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
set_task_cpu() should be rq invariant and only touch task state, it
currently fails to do so, which opens up a few races, since not all
callers hold both rq->locks.
Remove the relyance on rq->clock, as any site calling set_task_cpu()
should also do a remote clock update, which should ensure the observed
time between these two cpus is monotonic, as per
kernel/sched_clock.c:sched_clock_remote().
Therefore we can simply remove the clock_offset bits and be happy.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
sched_rr_get_param calls
task->sched_class->get_rr_interval(task) without protection
against a concurrent sched_setscheduler() call which modifies
task->sched_class.
Serialize the access with task_rq_lock(task) and hand the rq
pointer into get_rr_interval() as it's needed at least in the
sched_fair implementation.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <alpine.LFD.2.00.0912090930120.3089@localhost.localdomain>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
sched_getaffinity() is not protected against a concurrent
modification of the tasks affinity.
Serialize the access with task_rq_lock(task).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <20091208202026.769251187@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
* git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/sysctl-2.6: (43 commits)
security/tomoyo: Remove now unnecessary handling of security_sysctl.
security/tomoyo: Add a special case to handle accesses through the internal proc mount.
sysctl: Drop & in front of every proc_handler.
sysctl: Remove CTL_NONE and CTL_UNNUMBERED
sysctl: kill dead ctl_handler definitions.
sysctl: Remove the last of the generic binary sysctl support
sysctl net: Remove unused binary sysctl code
sysctl security/tomoyo: Don't look at ctl_name
sysctl arm: Remove binary sysctl support
sysctl x86: Remove dead binary sysctl support
sysctl sh: Remove dead binary sysctl support
sysctl powerpc: Remove dead binary sysctl support
sysctl ia64: Remove dead binary sysctl support
sysctl s390: Remove dead sysctl binary support
sysctl frv: Remove dead binary sysctl support
sysctl mips/lasat: Remove dead binary sysctl support
sysctl drivers: Remove dead binary sysctl support
sysctl crypto: Remove dead binary sysctl support
sysctl security/keys: Remove dead binary sysctl support
sysctl kernel: Remove binary sysctl logic
...
Since (e761b77: cpu hotplug, sched: Introduce cpu_active_map and redo
sched domain managment) we have cpu_active_mask which is suppose to rule
scheduler migration and load-balancing, except it never (fully) did.
The particular problem being solved here is a crash in try_to_wake_up()
where select_task_rq() ends up selecting an offline cpu because
select_task_rq_fair() trusts the sched_domain tree to reflect the
current state of affairs, similarly select_task_rq_rt() trusts the
root_domain.
However, the sched_domains are updated from CPU_DEAD, which is after the
cpu is taken offline and after stop_machine is done. Therefore it can
race perfectly well with code assuming the domains are right.
Cure this by building the domains from cpu_active_mask on
CPU_DOWN_PREPARE.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (31 commits)
rcu: Make RCU's CPU-stall detector be default
rcu: Add expedited grace-period support for preemptible RCU
rcu: Enable fourth level of TREE_RCU hierarchy
rcu: Rename "quiet" functions
rcu: Re-arrange code to reduce #ifdef pain
rcu: Eliminate unneeded function wrapping
rcu: Fix grace-period-stall bug on large systems with CPU hotplug
rcu: Eliminate __rcu_pending() false positives
rcu: Further cleanups of use of lastcomp
rcu: Simplify association of forced quiescent states with grace periods
rcu: Accelerate callback processing on CPUs not detecting GP end
rcu: Mark init-time-only rcu_bootup_announce() as __init
rcu: Simplify association of quiescent states with grace periods
rcu: Rename dynticks_completed to completed_fqs
rcu: Enable synchronize_sched_expedited() fastpath
rcu: Remove inline from forward-referenced functions
rcu: Fix note_new_gpnum() uses of ->gpnum
rcu: Fix synchronization for rcu_process_gp_end() uses of ->completed counter
rcu: Prepare for synchronization fixes: clean up for non-NO_HZ handling of ->completed counter
rcu: Cleanup: balance rcu_irq_enter()/rcu_irq_exit() calls
...
We don't need to build mutex_spin_on_owner() if we have
CONFIG_DEBUG_MUTEXES or CONFIG_HAVE_DEFAULT_NO_SPIN_MUTEXES as
it won't be used under such configs.
Use CONFIG_MUTEX_SPIN_ON_OWNER as it gathers all the necessary
checks before building it.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <1259783357-8542-2-git-send-regression-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
This is a real fix for problem of utime/stime values decreasing
described in the thread:
http://lkml.org/lkml/2009/11/3/522
Now cputime is accounted in the following way:
- {u,s}time in task_struct are increased every time when the thread
is interrupted by a tick (timer interrupt).
- When a thread exits, its {u,s}time are added to signal->{u,s}time,
after adjusted by task_times().
- When all threads in a thread_group exits, accumulated {u,s}time
(and also c{u,s}time) in signal struct are added to c{u,s}time
in signal struct of the group's parent.
So {u,s}time in task struct are "raw" tick count, while
{u,s}time and c{u,s}time in signal struct are "adjusted" values.
And accounted values are used by:
- task_times(), to get cputime of a thread:
This function returns adjusted values that originates from raw
{u,s}time and scaled by sum_exec_runtime that accounted by CFS.
- thread_group_cputime(), to get cputime of a thread group:
This function returns sum of all {u,s}time of living threads in
the group, plus {u,s}time in the signal struct that is sum of
adjusted cputimes of all exited threads belonged to the group.
The problem is the return value of thread_group_cputime(),
because it is mixed sum of "raw" value and "adjusted" value:
group's {u,s}time = foreach(thread){{u,s}time} + exited({u,s}time)
This misbehavior can break {u,s}time monotonicity.
Assume that if there is a thread that have raw values greater
than adjusted values (e.g. interrupted by 1000Hz ticks 50 times
but only runs 45ms) and if it exits, cputime will decrease (e.g.
-5ms).
To fix this, we could do:
group's {u,s}time = foreach(t){task_times(t)} + exited({u,s}time)
But task_times() contains hard divisions, so applying it for
every thread should be avoided.
This patch fixes the above problem in the following way:
- Modify thread's exit (= __exit_signal()) not to use task_times().
It means {u,s}time in signal struct accumulates raw values instead
of adjusted values. As the result it makes thread_group_cputime()
to return pure sum of "raw" values.
- Introduce a new function thread_group_times(*task, *utime, *stime)
that converts "raw" values of thread_group_cputime() to "adjusted"
values, in same calculation procedure as task_times().
- Modify group's exit (= wait_task_zombie()) to use this introduced
thread_group_times(). It make c{u,s}time in signal struct to
have adjusted values like before this patch.
- Replace some thread_group_cputime() by thread_group_times().
This replacements are only applied where conveys the "adjusted"
cputime to users, and where already uses task_times() near by it.
(i.e. sys_times(), getrusage(), and /proc/<PID>/stat.)
This patch have a positive side effect:
- Before this patch, if a group contains many short-life threads
(e.g. runs 0.9ms and not interrupted by ticks), the group's
cputime could be invisible since thread's cputime was accumulated
after adjusted: imagine adjustment function as adj(ticks, runtime),
{adj(0, 0.9) + adj(0, 0.9) + ....} = {0 + 0 + ....} = 0.
After this patch it will not happen because the adjustment is
applied after accumulated.
v2:
- remove if()s, put new variables into signal_struct.
Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Spencer Candland <spencer@bluehost.com>
Cc: Americo Wang <xiyou.wangcong@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
LKML-Reference: <4B162517.8040909@jp.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
- Remove if({u,s}t)s because no one call it with NULL now.
- Use cputime_{add,sub}().
- Add ifndef-endif for prev_{u,s}time since they are used
only when !VIRT_CPU_ACCOUNTING.
Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Spencer Candland <spencer@bluehost.com>
Cc: Americo Wang <xiyou.wangcong@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
LKML-Reference: <4B1624C7.7040302@jp.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Anton Blanchard wrote:
> We allocate and zero cpu_isolated_map after the isolcpus
> __setup option has run. This means cpu_isolated_map always
> ends up empty and if CPUMASK_OFFSTACK is enabled we write to a
> cpumask that hasn't been allocated.
I introduced this regression in 49557e6203 (sched: Fix
boot crash by zalloc()ing most of the cpu masks).
Use the bootmem allocator if they set isolcpus=, otherwise
allocate and zero like normal.
Reported-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: peterz@infradead.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: <stable@kernel.org>
LKML-Reference: <200912021409.17013.rusty@rustcorp.com.au>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Tested-by: Anton Blanchard <anton@samba.org>
498657a478 incorrectly assumed
that preempt wasn't disabled around context_switch() and thus
was fixing imaginary problem. It also broke KVM because it
depended on ->sched_in() to be called with irq enabled so that
it can do smp calls from there.
Revert the incorrect commit and add comment describing different
contexts under with the two callbacks are invoked.
Avi: spotted transposed in/out in the added comment.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Avi Kivity <avi@redhat.com>
Cc: peterz@infradead.org
Cc: efault@gmx.de
Cc: rusty@rustcorp.com.au
LKML-Reference: <1259726212-30259-2-git-send-email-tj@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Use of msecs_to_jiffies() for nsecs_to_cputime() have some
problems:
- The type of msecs_to_jiffies()'s argument is unsigned int, so
it cannot convert msecs greater than UINT_MAX = about 49.7 days.
- msecs_to_jiffies() returns MAX_JIFFY_OFFSET if MSB of argument
is set, assuming that input was negative value. So it cannot
convert msecs greater than INT_MAX = about 24.8 days too.
This patch defines a new function nsecs_to_jiffies() that can
deal greater values, and that can deal all incoming values as
unsigned.
Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Spencer Candland <spencer@bluehost.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Amrico Wang <xiyou.wangcong@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <johnstul@linux.vnet.ibm.com>
LKML-Reference: <4B0E16E7.5070307@jp.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Now all task_{u,s}time() pairs are replaced by task_times().
And task_gtime() is too simple to be an inline function.
Cleanup them all.
Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Spencer Candland <spencer@bluehost.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Americo Wang <xiyou.wangcong@gmail.com>
LKML-Reference: <4B0E16D1.70902@jp.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Functions task_{u,s}time() are called in pair in almost all
cases. However task_stime() is implemented to call task_utime()
from its inside, so such paired calls run task_utime() twice.
It means we do heavy divisions (div_u64 + do_div) twice to get
utime and stime which can be obtained at same time by one set
of divisions.
This patch introduces a function task_times(*tsk, *utime,
*stime) to retrieve utime and stime at once in better, optimized
way.
Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Spencer Candland <spencer@bluehost.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Americo Wang <xiyou.wangcong@gmail.com>
LKML-Reference: <4B0E16AE.906@jp.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Tejun Heo