__get_page_state() has an open-coded for_each_cpu_mask() loop in it.
Tidy that up, then notice that the code was buggy:
while (cpu < NR_CPUS) {
unsigned long *in, *out, off;
if (!cpu_isset(cpu, *cpumask))
continue;
an obvious infinite loop. I guess we just never call it with a holey cpu
mask.
Even after my cpumask size-reduction work, this patch increases code size :(
Cc: Paul Jackson <pj@sgi.com>
Cc: Christoph Lameter <clameter@engr.sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
The cache reaper currently tries to free all alien caches and all remote
per cpu pages in each pass of cache_reap. For a machines with large number
of nodes (such as Altix) this may lead to sporadic delays of around ~10ms.
Interrupts are disabled while reclaiming creating unacceptable delays.
This patch changes that behavior by adding a per cpu reap_node variable.
Instead of attempting to free all caches, we free only one alien cache and
the per cpu pages from one remote node. That reduces the time spend in
cache_reap. However, doing so will lengthen the time it takes to
completely drain all remote per cpu pagesets and all alien caches. The
time needed will grow with the number of nodes in the system. All caches
are drained when they overflow their respective capacity. So the drawback
here is only that a bit of memory may be wasted for awhile longer.
Details:
1. Rename drain_remote_pages to drain_node_pages to allow the specification
of the node to drain of pcp pages.
2. Add additional functions init_reap_node, next_reap_node for NUMA
that manage a per cpu reap_node counter.
3. Add a reap_alien function that reaps only from the current reap_node.
For us this seems to be a critical issue. Holdoffs of an average of ~7ms
cause some HPC benchmarks to slow down significantly. F.e. NAS parallel
slows down dramatically. NAS parallel has a 12-16 seconds runtime w/o rotor
compared to 5.8 secs with the rotor patches. It gets down to 5.05 secs with
the additional interrupt holdoff reductions.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Some allocations are restricted to a limited set of nodes (due to memory
policies or cpuset constraints). If the page allocator is not able to find
enough memory then that does not mean that overall system memory is low.
In particular going postal and more or less randomly shooting at processes
is not likely going to help the situation but may just lead to suicide (the
whole system coming down).
It is better to signal to the process that no memory exists given the
constraints that the process (or the configuration of the process) has
placed on the allocation behavior. The process may be killed but then the
sysadmin or developer can investigate the situation. The solution is
similar to what we do when running out of hugepages.
This patch adds a check before we kill processes. At that point
performance considerations do not matter much so we just scan the zonelist
and reconstruct a list of nodes. If the list of nodes does not contain all
online nodes then this is a constrained allocation and we should kill the
current process.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Andi Kleen <ak@muc.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Change the find_next_best_node algorithm to correctly skip
over holes in the node online mask. Previously it would not handle
missing nodes correctly and cause crashes at boot.
[Written by Linus, tested by AK]
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Somehow I imagined that calling a NULL destructor would free a compound page
rather than oopsing. No, we must supply a default destructor, __free_pages_ok
using the order noted by prep_compound_page. hugetlb can still replace this
as before with its own free_huge_page pointer.
The case that needs this is not common: rarely does put_compound_page's
put_page_testzero bring the count down to 0. But if get_user_pages is applied
to some part of a compound page, without immediate release (e.g. AIO or
Infiniband), then it's possible for its put_page to come after the containing
vma has been unmapped and the driver done its free_pages.
That's just the kind of case compound pages are supposed to be guarding
against (but Nick points out, nor did PageReserved handle this right).
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
If a compound page has its own put_page_testzero destructor (the only current
example is free_huge_page), that is noted in page[1].mapping of the compound
page. But that's rather a poor place to keep it: functions which call
set_page_dirty_lock after get_user_pages (e.g. Infiniband's
__ib_umem_release) ought to be checking first, otherwise set_page_dirty is
liable to crash on what's not the address of a struct address_space.
And now I'm about to make that worse: it turns out that every compound page
needs a destructor, so we can no longer rely on hugetlb pages going their own
special way, to avoid further problems of page->mapping reuse. For example,
not many people know that: on 50% of i386 -Os builds, the first tail page of a
compound page purports to be PageAnon (when its destructor has an odd
address), which surprises page_add_file_rmap.
Keep the compound page destructor in page[1].lru.next instead. And to free up
the common pairing of mapping and index, also move compound page order from
index to lru.prev. Slab reuses page->lru too: but if we ever need slab to use
compound pages, it can easily stack its use above this.
(akpm: decoded version of the above: the tail pages of a compound page now
have ->mapping==NULL, so there's no need for the set_page_dirty[_lock]()
caller to check that they're not compund pages before doing the dirty).
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
percpu_data blindly allocates bootmem memory to store NR_CPUS instances of
cpudata, instead of allocating memory only for possible cpus.
As a preparation for changing that, we need to convert various 0 -> NR_CPUS
loops to use for_each_cpu().
(The above only applies to users of asm-generic/percpu.h. powerpc has gone it
alone and is presently only allocating memory for present CPUs, so it's
currently corrupting memory).
Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: James Bottomley <James.Bottomley@steeleye.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Jens Axboe <axboe@suse.de>
Cc: Anton Blanchard <anton@samba.org>
Acked-by: William Irwin <wli@holomorphy.com>
Cc: Andi Kleen <ak@muc.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
__meminit has overzelously been modified and crept its way into marking
cpuup callbacks as __meminit.
Signed-off-by: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Some bits for zone reclaim exists in 2.6.15 but they are not usable. This
patch fixes them up, removes unused code and makes zone reclaim usable.
Zone reclaim allows the reclaiming of pages from a zone if the number of
free pages falls below the watermarks even if other zones still have enough
pages available. Zone reclaim is of particular importance for NUMA
machines. It can be more beneficial to reclaim a page than taking the
performance penalties that come with allocating a page on a remote zone.
Zone reclaim is enabled if the maximum distance to another node is higher
than RECLAIM_DISTANCE, which may be defined by an arch. By default
RECLAIM_DISTANCE is 20. 20 is the distance to another node in the same
component (enclosure or motherboard) on IA64. The meaning of the NUMA
distance information seems to vary by arch.
If zone reclaim is not successful then no further reclaim attempts will
occur for a certain time period (ZONE_RECLAIM_INTERVAL).
This patch was discussed before. See
http://marc.theaimsgroup.com/?l=linux-kernel&m=113519961504207&w=2http://marc.theaimsgroup.com/?l=linux-kernel&m=113408418232531&w=2http://marc.theaimsgroup.com/?l=linux-kernel&m=113389027420032&w=2http://marc.theaimsgroup.com/?l=linux-kernel&m=113380938612205&w=2
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Add __meminit to the __init lineup to ensure functions default
to __init when memory hotplug is not enabled. Replace __devinit
with __meminit on functions that were changed when the memory
hotplug code was introduced.
Signed-off-by: Matt Tolentino <matthew.e.tolentino@intel.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Clarify in comments that GFP_ATOMIC means both "don't sleep" and "use
emergency pools", hence both ALLOC_HARDER and ALLOC_HIGH.
Signed-off-by: Paul Jackson <pj@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Let's switch mutex_debug_check_no_locks_freed() to take (addr, len) as
arguments instead, since all its callers were just calculating the 'to'
address for themselves anyway... (and sometimes doing so badly).
Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
more mutex debugging: check for held locks during memory freeing,
task exit, enable sysrq printouts, etc.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@infradead.org>
Provide a simple per-cpuset metric of memory pressure, tracking the -rate-
that the tasks in a cpuset call try_to_free_pages(), the synchronous
(direct) memory reclaim code.
This enables batch managers monitoring jobs running in dedicated cpusets to
efficiently detect what level of memory pressure that job is causing.
This is useful both on tightly managed systems running a wide mix of
submitted jobs, which may choose to terminate or reprioritize jobs that are
trying to use more memory than allowed on the nodes assigned them, and with
tightly coupled, long running, massively parallel scientific computing jobs
that will dramatically fail to meet required performance goals if they
start to use more memory than allowed to them.
This patch just provides a very economical way for the batch manager to
monitor a cpuset for signs of memory pressure. It's up to the batch
manager or other user code to decide what to do about it and take action.
==> Unless this feature is enabled by writing "1" to the special file
/dev/cpuset/memory_pressure_enabled, the hook in the rebalance
code of __alloc_pages() for this metric reduces to simply noticing
that the cpuset_memory_pressure_enabled flag is zero. So only
systems that enable this feature will compute the metric.
Why a per-cpuset, running average:
Because this meter is per-cpuset, rather than per-task or mm, the
system load imposed by a batch scheduler monitoring this metric is
sharply reduced on large systems, because a scan of the tasklist can be
avoided on each set of queries.
Because this meter is a running average, instead of an accumulating
counter, a batch scheduler can detect memory pressure with a single
read, instead of having to read and accumulate results for a period of
time.
Because this meter is per-cpuset rather than per-task or mm, the
batch scheduler can obtain the key information, memory pressure in a
cpuset, with a single read, rather than having to query and accumulate
results over all the (dynamically changing) set of tasks in the cpuset.
A per-cpuset simple digital filter (requires a spinlock and 3 words of data
per-cpuset) is kept, and updated by any task attached to that cpuset, if it
enters the synchronous (direct) page reclaim code.
A per-cpuset file provides an integer number representing the recent
(half-life of 10 seconds) rate of direct page reclaims caused by the tasks
in the cpuset, in units of reclaims attempted per second, times 1000.
Signed-off-by: Paul Jackson <pj@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Try to streamline free_pages_bulk by ensuring callers don't pass in a
'count' that exceeds the list size.
Some cleanups:
Rename __free_pages_bulk to __free_one_page.
Put the page list manipulation from __free_pages_ok into free_one_page.
Make __free_pages_ok static.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Use zone_pcp everywhere even though NUMA code "knows" the internal details
of the zone. Stop other people trying to copy, and it looks nicer.
Also, only print the pagesets of online cpus in zoneinfo.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: "Seth, Rohit" <rohit.seth@intel.com>
Cc: Christoph Lameter <christoph@lameter.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
As recently there has been lot of traffic on the right values for batch and
high water marks for per_cpu_pagelists. This patch makes these two
variables configurable through /proc interface.
A new tunable /proc/sys/vm/percpu_pagelist_fraction is added. This entry
controls the fraction of pages at most in each zone that are allocated for
each per cpu page list. The min value for this is 8. It means that we
don't allow more than 1/8th of pages in each zone to be allocated in any
single per_cpu_pagelist.
The batch value of each per cpu pagelist is also updated as a result. It
is set to pcp->high/4. The upper limit of batch is (PAGE_SHIFT * 8)
Signed-off-by: Rohit Seth <rohit.seth@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
For some reason there is an #ifdef CONFIG_NUMA within another #ifdef
CONFIG_NUMA in the page allocator. Remove innermost #ifdef CONFIG_NUMA
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Hugh says:
page_alloc_cpu_notify() specifically contains code to
/* Add dead cpu's page_states to our own. */
which handles this more efficiently.
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Optimise page_state manipulations by introducing interrupt unsafe accessors
to page_state fields. Callers must provide their own locking (either
disable interrupts or not update from interrupt context).
Switch over the hot callsites that can easily be moved under interrupts off
sections.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Give j and r meaningful names.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
The use k in the inner loop means that the highest zone nr is always used
if any zone of a node is populated. This means that the policy zone is not
correctly determined on arches that do no use HIGHMEM like ia64.
Change the loop to decrement k which also simplifies the BUG_ON.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Currently the function to build a zonelist for a BIND policy has the side
effect to set the policy_zone. This seems to be a bit strange. policy
zone seems to not be initialized elsewhere and therefore 0. Do we police
ZONE_DMA if no bind policy has been used yet?
This patch moves the determination of the zone to apply policies to into
the page allocator. We determine the zone while building the zonelist for
nodes.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Simplify build_zonelists_node by removing the case statement.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
There are numerous places we check whether a zone is populated or not.
Provide a helper function to check for populated zones and convert all
checks for zone->present_pages.
Signed-off-by: Con Kolivas <kernel@kolivas.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Cut down size slightly by not passing bad_page the function name (it should be
able to be determined by dump_stack()). And cut down the number of printks in
bad_page.
Also, cut down some branching in the destroy_compound_page path.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Add dma32 to zone statistics. Also attempt to arrange struct page_state a
bit better (visually).
Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Andi Kleen <ak@muc.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
The attached patch cleans up the way the bootmem allocator frees pages.
A new function, __free_pages_bootmem(), is provided in mm/page_alloc.c that is
called from mm/bootmem.c to turn pages over to the main allocator. All the
bits of code to initialise pages (clearing PG_reserved and setting the page
count) are moved to here. The checks on page validity are removed, on the
assumption that the struct page arrays will have been prepared correctly.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Small cleanups that does not change generated code with the gcc's I've tested
with.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
read_page_state and __get_page_state only traverse online CPUs, which will
cause results to fluctuate when CPUs are plugged in or out.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
bad_range is supposed to be a temporary check. It would be a pity to throw it
out. Make it depend on CONFIG_DEBUG_VM instead.
CONFIG_HOLES_IN_ZONE systems were relying on this to check pfn_valid in the
page allocator. Add that to page_is_buddy instead.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Micro optimise some conditionals where we don't need lazy evaluation.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Slightly optimise some page allocation and freeing functions by taking
advantage of knowing whether or not interrupts are disabled.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
The NODES_SPAN_OTHER_NODES config option was created so that DISCONTIGMEM
could handle pSeries numa layouts. However, support for DISCONTIGMEM has
been replaced by SPARSEMEM on powerpc. As a result, this config option and
supporting code is no longer needed.
I have already sent a patch to Paul that removes the option from powerpc
specific code. This removes the arch independent piece. Doesn't really
matter which is applied first.
Signed-off-by: Mike Kravetz <kravetz@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Two changes to the setting of the ALLOC_CPUSET flag in
mm/page_alloc.c:__alloc_pages()
- A bug fix - the "ignoring mins" case should not be honoring ALLOC_CPUSET.
This case of all cases, since it is handling a request that will free up
more memory than is asked for (exiting tasks, e.g.) should be allowed to
escape cpuset constraints when memory is tight.
- A logic change to make it simpler. Honor cpusets even on GFP_ATOMIC
(!wait) requests. With this, cpuset confinement applies to all requests
except ALLOC_NO_WATERMARKS, so that in a subsequent cleanup patch, I can
remove the ALLOC_CPUSET flag entirely. Since I don't know any real reason
this logic has to be either way, I am choosing the path of the simplest
code.
Signed-off-by: Paul Jackson <pj@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
The code to clamp batch sizes to 2^n - 1 went missing and an extra
check got added, which must have been a hunk of the "higer order pcp
batch refills" work sneaking in.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
I believe this patch is required to fix breakage in the asynch reclaim
watermark logic introduced by this patch:
http://www.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=7fb1d9fca5c6e3b06773b69165a73f3fb786b8ee
Just some background of the watermark logic in case it isn't clear...
Basically what we have is this:
--- pages_high
|
| (a)
|
--- pages_low
|
| (b)
|
--- pages_min
|
| (c)
|
--- 0
Now when pages_low is reached, we want to kick asynch reclaim, which gives us
an interval of "b" before we must start synch reclaim, and gives kswapd an
interval of "a" before it need go back to sleep.
When pages_min is reached, normal allocators must enter synch reclaim, but
PF_MEMALLOC, ALLOC_HARDER, and ALLOC_HIGH (ie. atomic allocations, recursive
allocations, etc.) get access to varying amounts of the reserve "c".
Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: "Seth, Rohit" <rohit.seth@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
It used to be the case that PG_reserved pages were silently never freed, but
in 2.6.15-rc1 they may be freed with a "Bad page state" message. We should
work through such cases as they appear, fixing the code; but for now it's
safer to issue the message without freeing the page, leaving PG_reserved set.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
It looks like snd_xxx is not the only nopage to be using PageReserved as a way
of holding a high-order page together: which no longer works, but is masked by
our failure to free from VM_RESERVED areas. We cannot fix that bug without
first substituting another way to hold the high-order page together, while
farming out the 0-order pages from within it.
That's just what PageCompound is designed for, but it's been kept under
CONFIG_HUGETLB_PAGE. Remove the #ifdefs: which saves some space (out- of-line
put_page), doesn't slow down what most needs to be fast (already using
hugetlb), and unifies the way we handle high-order pages.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
We must reassign z before looping through the zones kicking kswapd,
since it will be NULL if we hit an OOM condition and jump back to the
beginning again. 'z' is initially assigned before the restart: label. So
move the restart label up a little.
Signed-off-by: Jens Axboe <axboe@suse.de>
Has been introduced for x86-64 at some point to save memory
in struct page, but has been obsolete for some time. Just
remove it.
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Add a new 4GB GFP_DMA32 zone between the GFP_DMA and GFP_NORMAL zones.
As a bit of historical background: when the x86-64 port
was originally designed we had some discussion if we should
use a 16MB DMA zone like i386 or a 4GB DMA zone like IA64 or
both. Both was ruled out at this point because it was in early
2.4 when VM is still quite shakey and had bad troubles even
dealing with one DMA zone. We settled on the 16MB DMA zone mainly
because we worried about older soundcards and the floppy.
But this has always caused problems since then because
device drivers had trouble getting enough DMA able memory. These days
the VM works much better and the wide use of NUMA has proven
it can deal with many zones successfully.
So this patch adds both zones.
This helps drivers who need a lot of memory below 4GB because
their hardware is not accessing more (graphic drivers - proprietary
and free ones, video frame buffer drivers, sound drivers etc.).
Previously they could only use IOMMU+16MB GFP_DMA, which
was not enough memory.
Another common problem is that hardware who has full memory
addressing for >4GB misses it for some control structures in memory
(like transmit rings or other metadata). They tended to allocate memory
in the 16MB GFP_DMA or the IOMMU/swiotlb then using pci_alloc_consistent,
but that can tie up a lot of precious 16MB GFPDMA/IOMMU/swiotlb memory
(even on AMD systems the IOMMU tends to be quite small) especially if you have
many devices. With the new zone pci_alloc_consistent can just put
this stuff into memory below 4GB which works better.
One argument was still if the zone should be 4GB or 2GB. The main
motivation for 2GB would be an unnamed not so unpopular hardware
raid controller (mostly found in older machines from a particular four letter
company) who has a strange 2GB restriction in firmware. But
that one works ok with swiotlb/IOMMU anyways, so it doesn't really
need GFP_DMA32. I chose 4GB to be compatible with IA64 and because
it seems to be the most common restriction.
The new zone is so far added only for x86-64.
For other architectures who don't set up this
new zone nothing changes. Architectures can set a compatibility
define in Kconfig CONFIG_DMA_IS_DMA32 that will define GFP_DMA32
as GFP_DMA. Otherwise it's a nop because on 32bit architectures
it's normally not needed because GFP_NORMAL (=0) is DMA able
enough.
One problem is still that GFP_DMA means different things on different
architectures. e.g. some drivers used to have #ifdef ia64 use GFP_DMA
(trusting it to be 4GB) #elif __x86_64__ (use other hacks like
the swiotlb because 16MB is not enough) ... . This was quite
ugly and is now obsolete.
These should be now converted to use GFP_DMA32 unconditionally. I haven't done
this yet. Or best only use pci_alloc_consistent/dma_alloc_coherent
which will use GFP_DMA32 transparently.
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
The pages_high - pages_low and pages_low - pages_min deltas are the asynch
reclaim watermarks. As such, the should be in the same ratios as any other
zone for highmem zones. It is the pages_min - 0 delta which is the
PF_MEMALLOC reserve, and this is the region that isn't very useful for
highmem.
This patch ensures highmem systems have similar characteristics as non highmem
ones with the same amount of memory, and also that highmem zones get similar
reclaim pressures to other zones.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Clean up of __alloc_pages.
Restoration of previous behaviour, plus further cleanups by introducing an
'alloc_flags', removing the last of should_reclaim_zone.
Signed-off-by: Rohit Seth <rohit.seth@intel.com>
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
In __alloc_pages():
if ((p->flags & (PF_MEMALLOC | PF_MEMDIE)) && !in_interrupt()) {
/* go through the zonelist yet again, ignoring mins */
for (i = 0; zones[i] != NULL; i++) {
struct zone *z = zones[i];
page = buffered_rmqueue(z, order, gfp_mask);
if (page) {
zone_statistics(zonelist, z);
goto got_pg;
}
}
goto nopage; <<<< HERE!!! FAIL...
}
kswapd (which has PF_MEMALLOC flag) can fail to allocate memory even when
it allocates it with __GFP_NOFAIL flag.
Signed-Off-By: Pavel Emelianov <xemul@sw.ru>
Signed-Off-By: Denis Lunev <den@sw.ru>
Signed-Off-By: Kirill Korotaev <dev@sw.ru>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
I just hit a page allocation error on a kernel configured to support
64 CPUs. It spewed 60 completely useless unnecessary lines of info.
Signed-off-by: Dave Jones <davej@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
I didn't find any possible modular usage in the kernel.
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
In 'mm' change the explicit use of a for-loop using NR_CPUS into the
general for_each_cpu() constructs. This widens the scope of potential
future optimizations of the general constructs, as well as takes advantage
of the existing optimizations of first_cpu() and next_cpu(), which is
advantageous when the true CPU count is much smaller than NR_CPUS.
Signed-off-by: John Hawkes <hawkes@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This adds generic memory add/remove and supporting functions for memory
hotplug into a new file as well as a memory hotplug kernel config option.
Individual architecture patches will follow.
For now, disable memory hotplug when swsusp is enabled. There's a lot of
churn there right now. We'll fix it up properly once it calms down.
Signed-off-by: Matt Tolentino <matthew.e.tolentino@intel.com>
Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
See the "fixup bad_range()" patch for more information, but this actually
creates a the lock to protect things making assumptions about a zone's size
staying constant at runtime.
Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
pgdat->node_size_lock is basically only neeeded in one place in the normal
code: show_mem(), which is the arch-specific sysrq-m printing function.
Strictly speaking, the architectures not doing memory hotplug do no need this
locking in show_mem(). However, they are all included for completeness. This
should also make any future consolidation of all of the implementations a
little more straightforward.
This lock is also held in the sparsemem code during a memory removal, as
sections are invalidated. This is the place there pfn_valid() is made false
for a memory area that's being removed. The lock is only required when doing
pfn_valid() operations on memory which the user does not already have a
reference on the page, such as in show_mem().
Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
When doing memory hotplug operations, the size of existing zones can obviously
change. This means that zone->zone_{start_pfn,spanned_pages} can change.
There are currently no locks that protect these structure members. However,
they are rarely accessed at runtime. Outside of swsusp, the only place that I
can find is bad_range().
So, split bad_range() up into two pieces: one that needs to be locked and
anther that doesn't.
Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
If a zone is empty at boot-time and then hot-added to later, it needs to run
the same init code that would have been run on it at boot.
This patch breaks out zone table and per-cpu-pages functions for use by the
hotplug code. You can almost see all of the free_area_init_core() function on
one page now. :)
Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Christoph Lameter demonstrated very poor scalability on the SGI 512-way, with
a many-threaded application which concurrently initializes different parts of
a large anonymous area.
This patch corrects that, by using a separate spinlock per page table page, to
guard the page table entries in that page, instead of using the mm's single
page_table_lock. (But even then, page_table_lock is still used to guard page
table allocation, and anon_vma allocation.)
In this implementation, the spinlock is tucked inside the struct page of the
page table page: with a BUILD_BUG_ON in case it overflows - which it would in
the case of 32-bit PA-RISC with spinlock debugging enabled.
Splitting the lock is not quite for free: another cacheline access. Ideally,
I suppose we would use split ptlock only for multi-threaded processes on
multi-cpu machines; but deciding that dynamically would have its own costs.
So for now enable it by config, at some number of cpus - since the Kconfig
language doesn't support inequalities, let preprocessor compare that with
NR_CPUS. But I don't think it's worth being user-configurable: for good
testing of both split and unsplit configs, split now at 4 cpus, and perhaps
change that to 8 later.
There is a benefit even for singly threaded processes: kswapd can be attacking
one part of the mm while another part is busy faulting.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Remove PageReserved() calls from core code by tightening VM_RESERVED
handling in mm/ to cover PageReserved functionality.
PageReserved special casing is removed from get_page and put_page.
All setting and clearing of PageReserved is retained, and it is now flagged
in the page_alloc checks to help ensure we don't introduce any refcount
based freeing of Reserved pages.
MAP_PRIVATE, PROT_WRITE of VM_RESERVED regions is tentatively being
deprecated. We never completely handled it correctly anyway, and is be
reintroduced in future if required (Hugh has a proof of concept).
Once PageReserved() calls are removed from kernel/power/swsusp.c, and all
arch/ and driver code, the Set and Clear calls, and the PG_reserved bit can
be trivially removed.
Last real user of PageReserved is swsusp, which uses PageReserved to
determine whether a struct page points to valid memory or not. This still
needs to be addressed (a generic page_is_ram() should work).
A last caveat: the ZERO_PAGE is now refcounted and managed with rmap (and
thus mapcounted and count towards shared rss). These writes to the struct
page could cause excessive cacheline bouncing on big systems. There are a
number of ways this could be addressed if it is an issue.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Refcount bug fix for filemap_xip.c
Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Set the low water mark for hot pages in pcp to zero.
(akpm: for the life of me I cannot remember why we created pcp->low. Neither
can Martin and the changelog is silent. Maybe it was just a brainfart, but I
have this feeling that there was a reason. If not, we should remove the
fields completely. We'll see.)
Signed-off-by: Rohit Seth <rohit.seth@intel.com>
Cc: <linux-mm@kvack.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Increase the page allocator's per-cpu magazines from 1/4MB to 1/2MB.
Over 100+ runs for a workload, the difference in mean is about 2%. The best
results for both are almost same. Though the max variation in results with
1/2MB is only 2.2%, whereas with 1/4MB it is 12%.
Signed-off-by: Rohit Seth <rohit.seth@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Beginning of gfp_t annotations:
- -Wbitwise added to CHECKFLAGS
- old __bitwise renamed to __bitwise__
- __bitwise defined to either __bitwise__ or nothing, depending on
__CHECK_ENDIAN__ being defined
- gfp_t switched from __nocast to __bitwise__
- force cast to gfp_t added to __GFP_... constants
- new helper - gfp_zone(); extracts zone bits out of gfp_t value and casts
the result to int
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
The NUMA counters in struct per_cpu_pageset (linux/mmzone.h) are never
cleared today. This works ok for CPU 0 on NUMA machines because
boot_pageset[] is already zero, but for other CPU:s this results in
uninitialized counters.
Signed-off-by: Magnus Damm <magnus@valinux.co.jp>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
- added typedef unsigned int __nocast gfp_t;
- replaced __nocast uses for gfp flags with gfp_t - it gives exactly
the same warnings as far as sparse is concerned, doesn't change
generated code (from gcc point of view we replaced unsigned int with
typedef) and documents what's going on far better.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Use the add_taint() interface for setting tainted bit flags instead of
doing it manually.
Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This patch makes use of the previously underutilized cpuset flag
'mem_exclusive' to provide what amounts to another layer of memory placement
resolution. With this patch, there are now the following four layers of
memory placement available:
1) The whole system (interrupt and GFP_ATOMIC allocations can use this),
2) The nearest enclosing mem_exclusive cpuset (GFP_KERNEL allocations can use),
3) The current tasks cpuset (GFP_USER allocations constrained to here), and
4) Specific node placement, using mbind and set_mempolicy.
These nest - each layer is a subset (same or within) of the previous.
Layer (2) above is new, with this patch. The call used to check whether a
zone (its node, actually) is in a cpuset (in its mems_allowed, actually) is
extended to take a gfp_mask argument, and its logic is extended, in the case
that __GFP_HARDWALL is not set in the flag bits, to look up the cpuset
hierarchy for the nearest enclosing mem_exclusive cpuset, to determine if
placement is allowed. The definition of GFP_USER, which used to be identical
to GFP_KERNEL, is changed to also set the __GFP_HARDWALL bit, in the previous
cpuset_gfp_hardwall_flag patch.
GFP_ATOMIC and GFP_KERNEL allocations will stay within the current tasks
cpuset, so long as any node therein is not too tight on memory, but will
escape to the larger layer, if need be.
The intended use is to allow something like a batch manager to handle several
jobs, each job in its own cpuset, but using common kernel memory for caches
and such. Swapper and oom_kill activity is also constrained to Layer (2). A
task in or below one mem_exclusive cpuset should not cause swapping on nodes
in another non-overlapping mem_exclusive cpuset, nor provoke oom_killing of a
task in another such cpuset. Heavy use of kernel memory for i/o caching and
such by one job should not impact the memory available to jobs in other
non-overlapping mem_exclusive cpusets.
This patch enables providing hardwall, inescapable cpusets for memory
allocations of each job, while sharing kernel memory allocations between
several jobs, in an enclosing mem_exclusive cpuset.
Like Dinakar's patch earlier to enable administering sched domains using the
cpu_exclusive flag, this patch also provides a useful meaning to a cpuset flag
that had previously done nothing much useful other than restrict what cpuset
configurations were allowed.
Signed-off-by: Paul Jackson <pj@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Mark variables which are usually accessed for reads with __readmostly.
Signed-off-by: Alok N Kataria <alokk@calsoftinc.com>
Signed-off-by: Shai Fultheim <shai@scalex86.org>
Signed-off-by: Ravikiran Thirumalai <kiran@scalex86.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Move some more frequently read variables that showed up during some of our
performance tests as sometimes ending up in hot cachelines to the
read_mostly section.
Fix: Move the __read_mostly from before hpet_usec_quotient to follow the
variable like the other uses of __read_mostly.
Signed-off-by: Alok N Kataria <alokk@calsoftinc.com>
Signed-off-by: Christoph Lameter <christoph@scalex86.org>
Signed-off-by: Shai Fultheim <shai@scalex86.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Add page_state info to the per-node meminfo file in sysfs. This is mostly
just for informational purposes.
The lack of this information was brought up recently during a discussion
regarding pagecache clearing, and I put this patch together to test out one
of the suggestions.
It seems like interesting info to have, so I'm submitting the patch.
Signed-off-by: Martin Hicks <mort@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Christoph Lameter and Marcelo Tosatti asked to get rid of the
atomic_inc_and_test() to cleanup the atomic ops in the zone reclaim code.
Signed-off-by: Martin Hicks <mort@sgi.com>
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This bitop does not need to be atomic because it is performed when there will
be no references to the page (ie. the page is being freed).
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
We are iterating over all nodes in nr_free_zone_pages(). Because the
fallback zonelists contain all nodes in the system, and we walk all the
zonelists, we're counting memory multiple times (once for each node). This
caused us to make a size estimate of 32GB for an 8GB AMD64 box, which makes
all the dirty ratio calculations, etc incorrect.
There's still a further bug to fix from e820 holes causing overestimation
as well, but this fix is separate, and good as is, and fixes one class of
problems. Problem found by Badari, and tested by Ram Pai - thanks!
Signed-off-by: Martin J. Bligh <mbligh@mbligh.org>
Signed-off-by: Matt Dobson <colpatch@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Originally __free_pages_bulk used the relative page number within a zone to
define its buddies. This meant that to maintain the "maximally aligned"
requirements (that an allocation of size N will be aligned at least to N
physically) zones had to also be aligned to 1<<MAX_ORDER pages. When
__free_pages_bulk was updated to use the relative page frame numbers of the
free'd pages to pair buddies this released the alignment constraint on the
'left' edge of the zone. This allows _either_ edge of the zone to contain
partial MAX_ORDER sized buddies. These simply never will have matching
buddies and thus will never make it to the 'top' of the pyramid.
The patch below removes a now redundant check ensuring that the mem_map was
aligned to MAX_ORDER.
Signed-off-by: Andy Whitcroft <apw@shadowen.org>
Cc: Christoph Lameter <christoph@lameter.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Remove completly bogus comment from did_some_progress != 0 handling (that
same comment is a few lines below on did_some_progress = 0 case, where it
belongs).
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
I spotted this issue while in memmap_init last week. I can't say the
change has any test coverage by me. start_pfn was formerly used in main
"for" loop. The fix is replace start_pfn with pfn.
Signed-off-by: Bob Picco <bob.picco@hp.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Make sparse's initalization be accessible at runtime. This allows sparse
mappings to be created after boot in a hotplug situation.
This patch is separated from the previous one just to give an indication how
much of the sparse infrastructure is *just* for hotplug memory.
The section_mem_map doesn't really store a pointer. It stores something that
is convenient to do some math against to get a pointer. It isn't valid to
just do *section_mem_map, so I don't think it should be stored as a pointer.
There are a couple of things I'd like to store about a section. First of all,
the fact that it is !NULL does not mean that it is present. There could be
such a combination where section_mem_map *is* NULL, but the math gets you
properly to a real mem_map. So, I don't think that check is safe.
Since we're storing 32-bit-aligned structures, we have a few bits in the
bottom of the pointer to play with. Use one bit to encode whether there's
really a mem_map there, and the other one to tell whether there's a valid
section there. We need to distinguish between the two because sometimes
there's a gap between when a section is discovered to be present and when we
can get the mem_map for it.
Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: Jack Steiner <steiner@sgi.com>
Signed-off-by: Bob Picco <bob.picco@hp.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
The part of the sparsemem patch which modifies memmap_init_zone() has recently
become a problem. It changes behavior so that there is a call to
pfn_to_page() for each individual page inside of a node's range:
node_start_pfn through node_end_pfn. It used to simply do this once, at the
beginning of the node, but having sparsemem's non-contiguous mem_map[]s inside
of a node made it necessary to change.
Mike Kravetz recently wrote a patch which made the NUMA code accept some new
kinds of layouts. The system's memory was laid out like this, with node 0's
memory in two pieces: one before and one after node 1's memory:
Node 0: +++++ +++++
Node 1: +++++
Previous behavior before Mike's patch was to assign nodes like this:
Node 0: 00000 XXXXX
Node 1: 11111
Where the 'X' areas were simply thrown away. The new behavior was to make the
pg_data_t span node 0 across all of its areas, including areas that are really
node 1's: Node 0: 000000000000000 Node 1: 11111
This wastes a little bit of mem_map space, but ends up being OK, and more
fully utilizes the system's memory. memmap_init_zone() initializes all of the
"struct page"s for node 0, even for the "hole", but those never get used,
because there is no pfn_to_page() that resolves to those pages. However, only
calling pfn_to_page() once, memmap_init_zone() always uses the pages that were
allocated for node0->node_mem_map because:
struct page *start = pfn_to_page(start_pfn);
// effectively start = &node->node_mem_map[0]
for (page = start; page < (start + size); page++) {
init_page_here();...
page++;
}
Slow, and wasteful, but generally harmless.
But, modify that to call pfn_to_page() for each loop iteration (like sparsemem
does):
for (pfn = start_pfn; pfn < < (start_pfn + size); pfn++++) {
page = pfn_to_page(pfn);
}
And you end up trying to initialize node 1's pages too early, along with bogus
data from node 0. This patch checks for those weird layouts and declines to
touch the pages, making the more frequent pfn_to_page() calls OK to do.
Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Sparsemem abstracts the use of discontiguous mem_maps[]. This kind of
mem_map[] is needed by discontiguous memory machines (like in the old
CONFIG_DISCONTIGMEM case) as well as memory hotplug systems. Sparsemem
replaces DISCONTIGMEM when enabled, and it is hoped that it can eventually
become a complete replacement.
A significant advantage over DISCONTIGMEM is that it's completely separated
from CONFIG_NUMA. When producing this patch, it became apparent in that NUMA
and DISCONTIG are often confused.
Another advantage is that sparse doesn't require each NUMA node's ranges to be
contiguous. It can handle overlapping ranges between nodes with no problems,
where DISCONTIGMEM currently throws away that memory.
Sparsemem uses an array to provide different pfn_to_page() translations for
each SECTION_SIZE area of physical memory. This is what allows the mem_map[]
to be chopped up.
In order to do quick pfn_to_page() operations, the section number of the page
is encoded in page->flags. Part of the sparsemem infrastructure enables
sharing of these bits more dynamically (at compile-time) between the
page_zone() and sparsemem operations. However, on 32-bit architectures, the
number of bits is quite limited, and may require growing the size of the
page->flags type in certain conditions. Several things might force this to
occur: a decrease in the SECTION_SIZE (if you want to hotplug smaller areas of
memory), an increase in the physical address space, or an increase in the
number of used page->flags.
One thing to note is that, once sparsemem is present, the NUMA node
information no longer needs to be stored in the page->flags. It might provide
speed increases on certain platforms and will be stored there if there is
room. But, if out of room, an alternate (theoretically slower) mechanism is
used.
This patch introduces CONFIG_FLATMEM. It is used in almost all cases where
there used to be an #ifndef DISCONTIG, because SPARSEMEM and DISCONTIGMEM
often have to compile out the same areas of code.
Signed-off-by: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Martin Bligh <mbligh@aracnet.com>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Yasunori Goto <y-goto@jp.fujitsu.com>
Signed-off-by: Bob Picco <bob.picco@hp.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
There is some confusion that arose when working on SPARSEMEM patch between
what is needed for DISCONTIG vs. NUMA.
Multiple pg_data_t's are needed for DISCONTIGMEM or NUMA, independently.
All of the current NUMA implementations require an implementation of
DISCONTIG. Because of this, quite a lot of code which is really needed for
NUMA is actually under DISCONTIG #ifdefs. For SPARSEMEM, we changed some
of these #ifdefs to CONFIG_NUMA, but that broke the DISCONTIG=y and NUMA=n
case.
Introducing this new NEED_MULTIPLE_NODES config option allows code that is
needed for both NUMA or DISCONTIG to be separated out from code that is
specific to DISCONTIG.
One great advantage of this approach is that it doesn't require every
architecture to be converted over. All of the current implementations
should "just work", only the ones implementing SPARSEMEM will have to be
fixed up.
The change to free_area_init() makes it work inside, or out of the new
config option.
Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Generify the value fields in the page_flags. The aim is to allow the location
and size of these fields to be varied. Additionally we want to move away from
fixed allocations per field whilst still enforcing the overall bit utilisation
limits. We rely on the compiler to spot and optimise the accessor functions.
Signed-off-by: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Introduce a simple allocator for the NUMA remap space. This space is very
scarce, used for structures which are best allocated node local.
This mechanism is also used on non-NUMA ia64 systems with a vmem_map to keep
the pgdat->node_mem_map initialized in a consistent place for all
architectures.
Issues:
o alloc_remap takes a node_id where we might expect a pgdat which was intended
to allow us to allocate the pgdat's using this mechanism; which we do not yet
do. Could have alloc_remap_node() and alloc_remap_nid() for this purpose.
Signed-off-by: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
The boot_pageset needs to be preserved for hotplugging and for off line
processors and nodes. Otherwise pointers will point into memory that has
now a different use. /proc/zoneinfo is currently showing strange results
if processors / nodes are not present.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Since free_pages_check complains if PG_reclaim or PG_slab is set, bad_page
ought to clear them to avoid repetitive reports (Nikita noticed this too).
Let prep_new_page check page_count and PG_slab as free_pages_check does.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Reduce size of the huge per_cpu_pageset structure in __initdata introduced
into mm1 with the pageset localization patchset. Use one specially
configured pageset per cpu for all zones and nodes during bootup.
- Avoid duplication of pageset initialization code.
- do the adding to the pageset list before potential free_pages_bulk
in free_hot_cold_page (otherwise we would have to hold a page
in a pageset during the period that the boot pagesets are in use).
- remove mistaken __cpuinitdata attribute and revert back to __initdata
for the boot pageset. A boot pageset is not necessary for cpu hotplug.
Tested for UP SMP NUMA on x86_64 (2.6.12-rc6-mm1): UP SMP NUMA Tested on
IA64 (2.6.12-rc5-mm2): NUMA (2.6.12-rc6-mm1 broken for IA64 because of
sparsemem patches)
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
The pageset array can potentially acquire a huge amount of memory on large
NUMA systems. F.e. on a system with 512 processors and 256 nodes there
will be 256*512 pagesets. If each pageset only holds 5 pages then we are
talking about 655360 pages.With a 16K page size on IA64 this results in
potentially 10 Gigabytes of memory being trapped in pagesets. The typical
cases are much less for smaller systems but there is still the potential of
memory being trapped in off node pagesets. Off node memory may be rarely
used if local memory is available and so we may potentially have memory in
seldom used pagesets without this patch.
The slab allocator flushes its per cpu caches every 2 seconds. The
following patch flushes the off node pageset caches in the same way by
tying into the slab flush.
The patch also changes /proc/zoneinfo to include the number of pages
currently in each pageset.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This patch provides more debug info when the system is OOM. It displays
memory stats (basically sysrq-m info) from __alloc_pages() when page
allocation fails and during OOM kill.
Thanks to Dave Jones for coming up with the idea.
Signed-off-by: Janet Morgan <janetmor@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
By making the offset argument of __read_page_state an unsigned long instead of
unsigned, we can avoid forcing the compiler to sign extend a usually constant
argument. This saves 1 instruction on x86-64.
Signed-off-by: Benjamin LaHaise <benjamin.c.lahaise@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
By making the offset argument of __mod_page_state an unsigned long instead
of unsigned, we can avoid forcing the compiler to sign extend a usually
constant argument. This saves 1 instruction on x86-64.
Signed-off-by: Benjamin LaHaise <benjamin.c.lahaise@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
try_to_free_pages accepts a third argument, order, but hasn't used it since
before 2.6.0. The following patch removes the argument and updates all the
calls to try_to_free_pages.
Signed-off-by: Darren Hart <dvhltc@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This patch modifies the way pagesets in struct zone are managed.
Each zone has a per-cpu array of pagesets. So any particular CPU has some
memory in each zone structure which belongs to itself. Even if that CPU is
not local to that zone.
So the patch relocates the pagesets for each cpu to the node that is nearest
to the cpu instead of allocating the pagesets in the (possibly remote) target
zone. This means that the operations to manage pages on remote zone can be
done with information available locally.
We play a macro trick so that non-NUMA pmachines avoid the additional
pointer chase on the page allocator fastpath.
AIM7 benchmark on a 32 CPU SGI Altix
w/o patches:
Tasks jobs/min jti jobs/min/task real cpu
1 484.68 100 484.6769 12.01 1.97 Fri Mar 25 11:01:42 2005
100 27140.46 89 271.4046 21.44 148.71 Fri Mar 25 11:02:04 2005
200 30792.02 82 153.9601 37.80 296.72 Fri Mar 25 11:02:42 2005
300 32209.27 81 107.3642 54.21 451.34 Fri Mar 25 11:03:37 2005
400 34962.83 78 87.4071 66.59 588.97 Fri Mar 25 11:04:44 2005
500 31676.92 75 63.3538 91.87 742.71 Fri Mar 25 11:06:16 2005
600 36032.69 73 60.0545 96.91 885.44 Fri Mar 25 11:07:54 2005
700 35540.43 77 50.7720 114.63 1024.28 Fri Mar 25 11:09:49 2005
800 33906.70 74 42.3834 137.32 1181.65 Fri Mar 25 11:12:06 2005
900 34120.67 73 37.9119 153.51 1325.26 Fri Mar 25 11:14:41 2005
1000 34802.37 74 34.8024 167.23 1465.26 Fri Mar 25 11:17:28 2005
with slab API changes and pageset patch:
Tasks jobs/min jti jobs/min/task real cpu
1 485.00 100 485.0000 12.00 1.96 Fri Mar 25 11:46:18 2005
100 28000.96 89 280.0096 20.79 150.45 Fri Mar 25 11:46:39 2005
200 32285.80 79 161.4290 36.05 293.37 Fri Mar 25 11:47:16 2005
300 40424.15 84 134.7472 43.19 438.42 Fri Mar 25 11:47:59 2005
400 39155.01 79 97.8875 59.46 590.05 Fri Mar 25 11:48:59 2005
500 37881.25 82 75.7625 76.82 730.19 Fri Mar 25 11:50:16 2005
600 39083.14 78 65.1386 89.35 872.79 Fri Mar 25 11:51:46 2005
700 38627.83 77 55.1826 105.47 1022.46 Fri Mar 25 11:53:32 2005
800 39631.94 78 49.5399 117.48 1169.94 Fri Mar 25 11:55:30 2005
900 36903.70 79 41.0041 141.94 1310.78 Fri Mar 25 11:57:53 2005
1000 36201.23 77 36.2012 160.77 1458.31 Fri Mar 25 12:00:34 2005
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Shobhit Dayal <shobhit@calsoftinc.com>
Signed-off-by: Shai Fultheim <Shai@Scalex86.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
When early zone reclaim is turned on the LRU is scanned more frequently when a
zone is low on memory. This limits when the zone reclaim can be called by
skipping the scan if another thread (either via kswapd or sync reclaim) is
already reclaiming from the zone.
Signed-off-by: Martin Hicks <mort@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
When using the early zone reclaim, it was noticed that allocating new pages
that should be spread across the whole system caused eviction of local pages.
This adds a new GFP flag to prevent early reclaim from happening during
certain allocation attempts. The example that is implemented here is for page
cache pages. We want page cache pages to be spread across the whole system,
and we don't want page cache pages to evict other pages to get local memory.
Signed-off-by: Martin Hicks <mort@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This is the core of the (much simplified) early reclaim. The goal of this
patch is to reclaim some easily-freed pages from a zone before falling back
onto another zone.
One of the major uses of this is NUMA machines. With the default allocator
behavior the allocator would look for memory in another zone, which might be
off-node, before trying to reclaim from the current zone.
This adds a zone tuneable to enable early zone reclaim. It is selected on a
per-zone basis and is turned on/off via syscall.
Adding some extra throttling on the reclaim was also required (patch
4/4). Without the machine would grind to a crawl when doing a "make -j"
kernel build. Even with this patch the System Time is higher on
average, but it seems tolerable. Here are some numbers for kernbench
runs on a 2-node, 4cpu, 8Gig RAM Altix in the "make -j" run:
wall user sys %cpu ctx sw. sleeps
---- ---- --- ---- ------ ------
No patch 1009 1384 847 258 298170 504402
w/patch, no reclaim 880 1376 667 288 254064 396745
w/patch & reclaim 1079 1385 926 252 291625 548873
These numbers are the average of 2 runs of 3 "make -j" runs done right
after system boot. Run-to-run variability for "make -j" is huge, so
these numbers aren't terribly useful except to seee that with reclaim
the benchmark still finishes in a reasonable amount of time.
I also looked at the NUMA hit/miss stats for the "make -j" runs and the
reclaim doesn't make any difference when the machine is thrashing away.
Doing a "make -j8" on a single node that is filled with page cache pages
takes 700 seconds with reclaim turned on and 735 seconds without reclaim
(due to remote memory accesses).
The simple zone_reclaim syscall program is at
http://www.bork.org/~mort/sgi/zone_reclaim.c
Signed-off-by: Martin Hicks <mort@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Andrew Morton