mirror of https://gitee.com/openkylin/linux.git
10323 Commits
| Author | SHA1 | Message | Date |
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Ming Li
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a4a921aa5c |
mm/swap.c: put activate_page_pvecs and other pagevecs together
Put the activate_page_pvecs definition next to those of the other pagevecs, for clarity. Signed-off-by: Ming Li <mingli199x@qq.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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David Rientjes
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297880f4af |
mm, hugetlb_cgroup: round limit_in_bytes down to hugepage size
The page_counter rounds limits down to page size values. This makes sense, except in the case of hugetlb_cgroup where it's not possible to charge partial hugepages. If the hugetlb_cgroup margin is less than the hugepage size being charged, it will fail as expected. Round the hugetlb_cgroup limit down to hugepage size, since it is the effective limit of the cgroup. For consistency, round down PAGE_COUNTER_MAX as well when a hugetlb_cgroup is created: this prevents error reports when a user cannot restore the value to the kernel default. Signed-off-by: David Rientjes <rientjes@google.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Nikolay Borisov <kernel@kyup.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Konstantin Khlebnikov
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f4fcd55841 |
mm: enable RLIMIT_DATA by default with workaround for valgrind
Since commit
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Yongji Xie
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d5957d2fc2 |
mm: fix incorrect pfn passed to untrack_pfn() in remap_pfn_range()
We use generic hooks in remap_pfn_range() to help archs to track pfnmap
regions. The code is something like:
int remap_pfn_range()
{
...
track_pfn_remap(vma, &prot, pfn, addr, PAGE_ALIGN(size));
...
pfn -= addr >> PAGE_SHIFT;
...
untrack_pfn(vma, pfn, PAGE_ALIGN(size));
...
}
Here we can easily find the pfn is changed but not recovered before
untrack_pfn() is called. That's incorrect.
There are no known runtime effects - this is from inspection.
Signed-off-by: Yongji Xie <xyjxie@linux.vnet.ibm.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Matthew Wilcox <matthew.r.wilcox@intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Chris Wilson
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80c4bd7a5e |
mm/vmalloc: keep a separate lazy-free list
When mixing lots of vmallocs and set_memory_*() (which calls vm_unmap_aliases()) I encountered situations where the performance degraded severely due to the walking of the entire vmap_area list each invocation. One simple improvement is to add the lazily freed vmap_area to a separate lockless free list, such that we then avoid having to walk the full list on each purge. Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Reviewed-by: Roman Pen <r.peniaev@gmail.com> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Roman Pen <r.peniaev@gmail.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Toshi Kani <toshi.kani@hp.com> Cc: Shawn Lin <shawn.lin@rock-chips.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Alexander Kuleshov
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f705ac4b39 |
mm/memblock.c: move memblock_{add,reserve}_region into memblock_{add,reserve}
memblock_add_region() and memblock_reserve_region() do nothing specific
before the call of memblock_add_range(), only print debug output.
We can do the same in memblock_add() and memblock_reserve() since both
memblock_add_region() and memblock_reserve_region() are not used by
anybody outside of memblock.c and memblock_{add,reserve}() have the same
set of flags and nids.
Since memblock_add_region() and memblock_reserve_region() will be
inlined, there will not be functional changes, but will improve code
readability a little.
Signed-off-by: Alexander Kuleshov <kuleshovmail@gmail.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Tang Chen <tangchen@cn.fujitsu.com>
Cc: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Chen Yucong
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495367c051 |
mm/memory-failure.c: replace "MCE" with "Memory failure"
HWPoison was specific to some particular x86 platforms. And it is often
seen as high level machine check handler. And therefore, 'MCE' is used
for the format prefix of printk(). However, 'PowerNV' has also used
HWPoison for handling memory errors[1], so 'MCE' is no longer suitable
to memory_failure.c.
Additionally, 'MCE' and 'Memory failure' have different context. The
former belongs to exception context and the latter belongs to process
context. Furthermore, HWPoison can also be used for off-lining those
sub-health pages that do not trigger any machine check exception.
This patch aims to replace 'MCE' with a more appropriate prefix.
[1] commit
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Yang Shi
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340a43bed6 |
mm: thp: simplify the implementation of mk_huge_pmd()
The implementation of mk_huge_pmd looks verbose, it could be just simplified to one line code. Signed-off-by: Yang Shi <yang.shi@linaro.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Tetsuo Handa
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f44666b046 |
mm,oom: speed up select_bad_process() loop
Since commit
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Michal Hocko
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ec8d7c14ea |
mm, oom_reaper: do not mmput synchronously from the oom reaper context
Tetsuo has properly noted that mmput slow path might get blocked waiting for another party (e.g. exit_aio waits for an IO). If that happens the oom_reaper would be put out of the way and will not be able to process next oom victim. We should strive for making this context as reliable and independent on other subsystems as much as possible. Introduce mmput_async which will perform the slow path from an async (WQ) context. This will delay the operation but that shouldn't be a problem because the oom_reaper has reclaimed the victim's address space for most cases as much as possible and the remaining context shouldn't bind too much memory anymore. The only exception is when mmap_sem trylock has failed which shouldn't happen too often. The issue is only theoretical but not impossible. Signed-off-by: Michal Hocko <mhocko@suse.com> Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Michal Hocko
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bb8a4b7fd1 |
mm, oom_reaper: hide oom reaped tasks from OOM killer more carefully
Commit
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Michal Hocko
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31e49bfda1 |
mm, oom: protect !costly allocations some more for !CONFIG_COMPACTION
Joonsoo has reported that he is able to trigger OOM for !costly high order requests (heavy fork() workload close the OOM) with the new oom detection rework. This is because we rely only on should_reclaim_retry when the compaction is disabled and it only checks watermarks for the requested order and so we might trigger OOM when there is a lot of free memory. It is not very clear what are the usual workloads when the compaction is disabled. Relying on high order allocations heavily without any mechanism to create those orders except for unbound amount of reclaim is certainly not a good idea. To prevent from potential regressions let's help this configuration some. We have to sacrifice the determinsm though because there simply is none here possible. should_compact_retry implementation for !CONFIG_COMPACTION, which was empty so far, will do watermark check for order-0 on all eligible zones. This will cause retrying until either the reclaim cannot make any further progress or all the zones are depleted even for order-0 pages. This means that the number of retries is basically unbounded for !costly orders but that was the case before the rework as well so this shouldn't regress. [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/1463051677-29418-3-git-send-email-mhocko@kernel.org Reported-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Michal Hocko
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86a294a81f |
mm, oom, compaction: prevent from should_compact_retry looping for ever for costly orders
"mm: consider compaction feedback also for costly allocation" has
removed the upper bound for the reclaim/compaction retries based on the
number of reclaimed pages for costly orders. While this is desirable
the patch did miss a mis interaction between reclaim, compaction and the
retry logic. The direct reclaim tries to get zones over min watermark
while compaction backs off and returns COMPACT_SKIPPED when all zones
are below low watermark + 1<<order gap. If we are getting really close
to OOM then __compaction_suitable can keep returning COMPACT_SKIPPED a
high order request (e.g. hugetlb order-9) while the reclaim is not able
to release enough pages to get us over low watermark. The reclaim is
still able to make some progress (usually trashing over few remaining
pages) so we are not able to break out from the loop.
I have seen this happening with the same test described in "mm: consider
compaction feedback also for costly allocation" on a swapless system.
The original problem got resolved by "vmscan: consider classzone_idx in
compaction_ready" but it shows how things might go wrong when we
approach the oom event horizont.
The reason why compaction requires being over low rather than min
watermark is not clear to me. This check was there essentially since
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Michal Hocko
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7854ea6c28 |
mm: consider compaction feedback also for costly allocation
PAGE_ALLOC_COSTLY_ORDER retry logic is mostly handled inside
should_reclaim_retry currently where we decide to not retry after at
least order worth of pages were reclaimed or the watermark check for at
least one zone would succeed after reclaiming all pages if the reclaim
hasn't made any progress. Compaction feedback is mostly ignored and we
just try to make sure that the compaction did at least something before
giving up.
The first condition was added by
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Michal Hocko
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33c2d21438 |
mm, oom: protect !costly allocations some more
should_reclaim_retry will give up retries for higher order allocations if none of the eligible zones has any requested or higher order pages available even if we pass the watermak check for order-0. This is done because there is no guarantee that the reclaimable and currently free pages will form the required order. This can, however, lead to situations where the high-order request (e.g. order-2 required for the stack allocation during fork) will trigger OOM too early - e.g. after the first reclaim/compaction round. Such a system would have to be highly fragmented and there is no guarantee further reclaim/compaction attempts would help but at least make sure that the compaction was active before we go OOM and keep retrying even if should_reclaim_retry tells us to oom if - the last compaction round backed off or - we haven't completed at least MAX_COMPACT_RETRIES active compaction rounds. The first rule ensures that the very last attempt for compaction was not ignored while the second guarantees that the compaction has done some work. Multiple retries might be needed to prevent occasional pigggy backing of other contexts to steal the compacted pages before the current context manages to retry to allocate them. compaction_failed() is taken as a final word from the compaction that the retry doesn't make much sense. We have to be careful though because the first compaction round is MIGRATE_ASYNC which is rather weak as it ignores pages under writeback and gives up too easily in other situations. We therefore have to make sure that MIGRATE_SYNC_LIGHT mode has been used before we give up. With this logic in place we do not have to increase the migration mode unconditionally and rather do it only if the compaction failed for the weaker mode. A nice side effect is that the stronger migration mode is used only when really needed so this has a potential of smaller latencies in some cases. Please note that the compaction doesn't tell us much about how successful it was when returning compaction_made_progress so we just have to blindly trust that another retry is worthwhile and cap the number to something reasonable to guarantee a convergence. If the given number of successful retries is not sufficient for a reasonable workloads we should focus on the collected compaction tracepoints data and try to address the issue in the compaction code. If this is not feasible we can increase the retries limit. [mhocko@suse.com: fix warning] Link: http://lkml.kernel.org/r/20160512061636.GA4200@dhcp22.suse.cz Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <js1304@gmail.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Vladimir Davydov <vdavydov@virtuozzo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Michal Hocko
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ede3771373 |
mm: throttle on IO only when there are too many dirty and writeback pages
wait_iff_congested has been used to throttle allocator before it retried another round of direct reclaim to allow the writeback to make some progress and prevent reclaim from looping over dirty/writeback pages without making any progress. We used to do congestion_wait before commit |
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Michal Hocko
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0a0337e0d1 |
mm, oom: rework oom detection
__alloc_pages_slowpath has traditionally relied on the direct reclaim and did_some_progress as an indicator that it makes sense to retry allocation rather than declaring OOM. shrink_zones had to rely on zone_reclaimable if shrink_zone didn't make any progress to prevent from a premature OOM killer invocation - the LRU might be full of dirty or writeback pages and direct reclaim cannot clean those up. zone_reclaimable allows to rescan the reclaimable lists several times and restart if a page is freed. This is really subtle behavior and it might lead to a livelock when a single freed page keeps allocator looping but the current task will not be able to allocate that single page. OOM killer would be more appropriate than looping without any progress for unbounded amount of time. This patch changes OOM detection logic and pulls it out from shrink_zone which is too low to be appropriate for any high level decisions such as OOM which is per zonelist property. It is __alloc_pages_slowpath which knows how many attempts have been done and what was the progress so far therefore it is more appropriate to implement this logic. The new heuristic is implemented in should_reclaim_retry helper called from __alloc_pages_slowpath. It tries to be more deterministic and easier to follow. It builds on an assumption that retrying makes sense only if the currently reclaimable memory + free pages would allow the current allocation request to succeed (as per __zone_watermark_ok) at least for one zone in the usable zonelist. This alone wouldn't be sufficient, though, because the writeback might get stuck and reclaimable pages might be pinned for a really long time or even depend on the current allocation context. Therefore there is a backoff mechanism implemented which reduces the reclaim target after each reclaim round without any progress. This means that we should eventually converge to only NR_FREE_PAGES as the target and fail on the wmark check and proceed to OOM. The backoff is simple and linear with 1/16 of the reclaimable pages for each round without any progress. We are optimistic and reset counter for successful reclaim rounds. Costly high order pages mostly preserve their semantic and those without __GFP_REPEAT fail right away while those which have the flag set will back off after the amount of reclaimable pages reaches equivalent of the requested order. The only difference is that if there was no progress during the reclaim we rely on zone watermark check. This is more logical thing to do than previous 1<<order attempts which were a result of zone_reclaimable faking the progress. [vdavydov@virtuozzo.com: check classzone_idx for shrink_zone] [hannes@cmpxchg.org: separate the heuristic into should_reclaim_retry] [rientjes@google.com: use zone_page_state_snapshot for NR_FREE_PAGES] [rientjes@google.com: shrink_zones doesn't need to return anything] Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Vladimir Davydov <vdavydov@virtuozzo.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <js1304@gmail.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Michal Hocko
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c5d01d0d18 |
mm, compaction: simplify __alloc_pages_direct_compact feedback interface
__alloc_pages_direct_compact communicates potential back off by two variables: - deferred_compaction tells that the compaction returned COMPACT_DEFERRED - contended_compaction is set when there is a contention on zone->lock resp. zone->lru_lock locks __alloc_pages_slowpath then backs of for THP allocation requests to prevent from long stalls. This is rather messy and it would be much cleaner to return a single compact result value and hide all the nasty details into __alloc_pages_direct_compact. This patch shouldn't introduce any functional changes. Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <js1304@gmail.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Vladimir Davydov <vdavydov@virtuozzo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Michal Hocko
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c8f7de0bfa |
mm, compaction: distinguish between full and partial COMPACT_COMPLETE
COMPACT_COMPLETE now means that compaction and free scanner met. This is not very useful information if somebody just wants to use this feedback and make any decisions based on that. The current caller might be a poor guy who just happened to scan tiny portion of the zone and that could be the reason no suitable pages were compacted. Make sure we distinguish the full and partial zone walks. Consumers should treat COMPACT_PARTIAL_SKIPPED as a potential success and be optimistic in retrying. The existing users of COMPACT_COMPLETE are conservatively changed to use COMPACT_PARTIAL_SKIPPED as well but some of them should be probably reconsidered and only defer the compaction only for COMPACT_COMPLETE with the new semantic. This patch shouldn't introduce any functional changes. Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <js1304@gmail.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Vladimir Davydov <vdavydov@virtuozzo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Michal Hocko
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1d4746d395 |
mm, compaction: distinguish COMPACT_DEFERRED from COMPACT_SKIPPED
try_to_compact_pages() can currently return COMPACT_SKIPPED even when the compaction is defered for some zone just because zone DMA is skipped in 99% of cases due to watermark checks. This makes COMPACT_DEFERRED basically unusable for the page allocator as a feedback mechanism. Make sure we distinguish those two states properly and switch their ordering in the enum. This would mean that the COMPACT_SKIPPED will be returned only when all eligible zones are skipped. As a result COMPACT_DEFERRED handling for THP in __alloc_pages_slowpath will be more precise and we would bail out rather than reclaim. Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <js1304@gmail.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Vladimir Davydov <vdavydov@virtuozzo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Michal Hocko
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c46649deae |
mm, compaction: cover all compaction mode in compact_zone
The compiler is complaining after "mm, compaction: change COMPACT_
constants into enum"
mm/compaction.c: In function `compact_zone':
mm/compaction.c:1350:2: warning: enumeration value `COMPACT_DEFERRED' not handled in switch [-Wswitch]
switch (ret) {
^
mm/compaction.c:1350:2: warning: enumeration value `COMPACT_COMPLETE' not handled in switch [-Wswitch]
mm/compaction.c:1350:2: warning: enumeration value `COMPACT_NO_SUITABLE_PAGE' not handled in switch [-Wswitch]
mm/compaction.c:1350:2: warning: enumeration value `COMPACT_NOT_SUITABLE_ZONE' not handled in switch [-Wswitch]
mm/compaction.c:1350:2: warning: enumeration value `COMPACT_CONTENDED' not handled in switch [-Wswitch]
compaction_suitable is allowed to return only COMPACT_PARTIAL,
COMPACT_SKIPPED and COMPACT_CONTINUE so other cases are simply
impossible. Put a VM_BUG_ON to catch an impossible return value.
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Vladimir Davydov <vdavydov@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Michal Hocko
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ea7ab982b6 |
mm, compaction: change COMPACT_ constants into enum
Compaction code is doing weird dances between COMPACT_FOO -> int -> unsigned long But there doesn't seem to be any reason for that. All functions which return/use one of those constants are not expecting any other value so it really makes sense to define an enum for them and make it clear that no other values are expected. This is a pure cleanup and shouldn't introduce any functional changes. Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <js1304@gmail.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Vladimir Davydov <vdavydov@virtuozzo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Michal Hocko
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b6459cc154 |
vmscan: consider classzone_idx in compaction_ready
Motivation:
As pointed out by Linus [2][3] relying on zone_reclaimable as a way to
communicate the reclaim progress is rater dubious. I tend to agree,
not only it is really obscure, it is not hard to imagine cases where a
single page freed in the loop keeps all the reclaimers looping without
getting any progress because their gfp_mask wouldn't allow to get that
page anyway (e.g. single GFP_ATOMIC alloc and free loop). This is rather
rare so it doesn't happen in the practice but the current logic which we
have is rather obscure and hard to follow a also non-deterministic.
This is an attempt to make the OOM detection more deterministic and
easier to follow because each reclaimer basically tracks its own
progress which is implemented at the page allocator layer rather spread
out between the allocator and the reclaim. The more on the
implementation is described in the first patch.
I have tested several different scenarios but it should be clear that
testing OOM killer is quite hard to be representative. There is usually
a tiny gap between almost OOM and full blown OOM which is often time
sensitive. Anyway, I have tested the following 2 scenarios and I would
appreciate if there are more to test.
Testing environment: a virtual machine with 2G of RAM and 2CPUs without
any swap to make the OOM more deterministic.
1) 2 writers (each doing dd with 4M blocks to an xfs partition with 1G
file size, removes the files and starts over again) running in
parallel for 10s to build up a lot of dirty pages when 100 parallel
mem_eaters (anon private populated mmap which waits until it gets
signal) with 80M each.
This causes an OOM flood of course and I have compared both patched
and unpatched kernels. The test is considered finished after there
are no OOM conditions detected. This should tell us whether there are
any excessive kills or some of them premature (e.g. due to dirty pages):
I have performed two runs this time each after a fresh boot.
* base kernel
$ grep "Out of memory:" base-oom-run1.log | wc -l
78
$ grep "Out of memory:" base-oom-run2.log | wc -l
78
$ grep "Kill process" base-oom-run1.log | tail -n1
[ 91.391203] Out of memory: Kill process 3061 (mem_eater) score 39 or sacrifice child
$ grep "Kill process" base-oom-run2.log | tail -n1
[ 82.141919] Out of memory: Kill process 3086 (mem_eater) score 39 or sacrifice child
$ grep "DMA32 free:" base-oom-run1.log | sed 's@.*free:\([0-9]*\)kB.*@\1@' | calc_min_max.awk
min: 5376.00 max: 6776.00 avg: 5530.75 std: 166.50 nr: 61
$ grep "DMA32 free:" base-oom-run2.log | sed 's@.*free:\([0-9]*\)kB.*@\1@' | calc_min_max.awk
min: 5416.00 max: 5608.00 avg: 5514.15 std: 42.94 nr: 52
$ grep "DMA32.*all_unreclaimable? no" base-oom-run1.log | wc -l
1
$ grep "DMA32.*all_unreclaimable? no" base-oom-run2.log | wc -l
3
* patched kernel
$ grep "Out of memory:" patched-oom-run1.log | wc -l
78
miso@tiehlicka /mnt/share/devel/miso/kvm $ grep "Out of memory:" patched-oom-run2.log | wc -l
77
e grep "Kill process" patched-oom-run1.log | tail -n1
[ 497.317732] Out of memory: Kill process 3108 (mem_eater) score 39 or sacrifice child
$ grep "Kill process" patched-oom-run2.log | tail -n1
[ 316.169920] Out of memory: Kill process 3093 (mem_eater) score 39 or sacrifice child
$ grep "DMA32 free:" patched-oom-run1.log | sed 's@.*free:\([0-9]*\)kB.*@\1@' | calc_min_max.awk
min: 5420.00 max: 5808.00 avg: 5513.90 std: 60.45 nr: 78
$ grep "DMA32 free:" patched-oom-run2.log | sed 's@.*free:\([0-9]*\)kB.*@\1@' | calc_min_max.awk
min: 5380.00 max: 6384.00 avg: 5520.94 std: 136.84 nr: 77
e grep "DMA32.*all_unreclaimable? no" patched-oom-run1.log | wc -l
2
$ grep "DMA32.*all_unreclaimable? no" patched-oom-run2.log | wc -l
3
The patched kernel run noticeably longer while invoking OOM killer same
number of times. This means that the original implementation is much
more aggressive and triggers the OOM killer sooner. free pages stats
show that neither kernels went OOM too early most of the time, though. I
guess the difference is in the backoff when retries without any progress
do sleep for a while if there is memory under writeback or dirty which
is highly likely considering the parallel IO.
Both kernels have seen races where zone wasn't marked unreclaimable
and we still hit the OOM killer. This is most likely a race where
a task managed to exit between the last allocation attempt and the oom
killer invocation.
2) 2 writers again with 10s of run and then 10 mem_eaters to consume as much
memory as possible without triggering the OOM killer. This required a lot
of tuning but I've considered 3 consecutive runs in three different boots
without OOM as a success.
* base kernel
size=$(awk '/MemFree/{printf "%dK", ($2/10)-(16*1024)}' /proc/meminfo)
* patched kernel
size=$(awk '/MemFree/{printf "%dK", ($2/10)-(12*1024)}' /proc/meminfo)
That means 40M more memory was usable without triggering OOM killer. The
base kernel sometimes managed to handle the same as patched but it
wasn't consistent and failed in at least on of the 3 runs. This seems
like a minor improvement.
I was testing also GPF_REPEAT costly requests (hughetlb) with fragmented
memory and under memory pressure. The results are in patch 11 where the
logic is implemented. In short I can see huge improvement there.
I am certainly interested in other usecases as well as well as any
feedback. Especially those which require higher order requests.
This patch (of 14):
While playing with the oom detection rework [1] I have noticed that my
heavy order-9 (hugetlb) load close to OOM ended up in an endless loop
where the reclaim hasn't made any progress but did_some_progress didn't
reflect that and compaction_suitable was backing off because no zone is
above low wmark + 1 << order.
It turned out that this is in fact an old standing bug in
compaction_ready which ignores the requested_highidx and did the
watermark check for 0 classzone_idx. This succeeds for zone DMA most
of the time as the zone is mostly unused because of lowmem protection.
As a result costly high order allocatios always report a successfull
progress even when there was none. This wasn't a problem so far
because these allocations usually fail quite early or retry only few
times with __GFP_REPEAT but this will change after later patch in this
series so make sure to not lie about the progress and propagate
requested_highidx down to compaction_ready and use it for both the
watermak check and compaction_suitable to fix this issue.
[1] http://lkml.kernel.org/r/1459855533-4600-1-git-send-email-mhocko@kernel.org
[2] https://lkml.org/lkml/2015/10/12/808
[3] https://lkml.org/lkml/2015/10/13/597
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: Vladimir Davydov <vdavydov@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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|
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Rik van Riel
|
59dc76b0d4 |
mm: vmscan: reduce size of inactive file list
The inactive file list should still be large enough to contain readahead windows and freshly written file data, but it no longer is the only source for detecting multiple accesses to file pages. The workingset refault measurement code causes recently evicted file pages that get accessed again after a shorter interval to be promoted directly to the active list. With that mechanism in place, we can afford to (on a larger system) dedicate more memory to the active file list, so we can actually cache more of the frequently used file pages in memory, and not have them pushed out by streaming writes, once-used streaming file reads, etc. This can help things like database workloads, where only half the page cache can currently be used to cache the database working set. This patch automatically increases that fraction on larger systems, using the same ratio that has already been used for anonymous memory. [hannes@cmpxchg.org: cgroup-awareness] Signed-off-by: Rik van Riel <riel@redhat.com> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reported-by: Andres Freund <andres@anarazel.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
|
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Johannes Weiner
|
bbddabe2e4 |
mm: filemap: only do access activations on reads
Andres observed that his database workload is struggling with the transaction journal creating pressure on frequently read pages. Access patterns like transaction journals frequently write the same pages over and over, but in the majority of cases those pages are never read back. There are no caching benefits to be had for those pages, so activating them and having them put pressure on pages that do benefit from caching is a bad choice. Leave page activations to read accesses and don't promote pages based on writes alone. It could be said that partially written pages do contain cache-worthy data, because even if *userspace* does not access the unwritten part, the kernel still has to read it from the filesystem for correctness. However, a counter argument is that these pages enjoy at least *some* protection over other inactive file pages through the writeback cache, in the sense that dirty pages are written back with a delay and cache reclaim leaves them alone until they have been written back to disk. Should that turn out to be insufficient and we see increased read IO from partial writes under memory pressure, we can always go back and update grab_cache_page_write_begin() to take (pos, len) so that it can tell partial writes from pages that don't need partial reads. But for now, keep it simple. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reported-by: Andres Freund <andres@anarazel.de> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
|
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Rik van Riel
|
f0281a00fe |
mm: workingset: only do workingset activations on reads
This is a follow-up to http://www.spinics.net/lists/linux-mm/msg101739.html where Andres reported his database workingset being pushed out by the minimum size enforcement of the inactive file list - currently 50% of cache - as well as repeatedly written file pages that are never actually read. Two changes fell out of the discussions. The first change observes that pages that are only ever written don't benefit from caching beyond what the writeback cache does for partial page writes, and so we shouldn't promote them to the active file list where they compete with pages whose cached data is actually accessed repeatedly. This change comes in two patches - one for in-cache write accesses and one for refaults triggered by writes, neither of which should promote a cache page. Second, with the refault detection we don't need to set 50% of the cache aside for used-once cache anymore since we can detect frequently used pages even when they are evicted between accesses. We can allow the active list to be bigger and thus protect a bigger workingset that isn't challenged by streamers. Depending on the access patterns, this can increase major faults during workingset transitions for better performance during stable phases. This patch (of 3): When rewriting a page, the data in that page is replaced with new data. This means that evicting something else from the active file list, in order to cache data that will be replaced by something else, is likely to be a waste of memory. It is better to save the active list for frequently read pages, because reads actually use the data that is in the page. This patch ignores partial writes, because it is unclear whether the complexity of identifying those is worth any potential performance gain obtained from better caching pages that see repeated partial writes at large enough intervals to not get caught by the use-twice promotion code used for the inactive file list. Signed-off-by: Rik van Riel <riel@redhat.com> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reported-by: Andres Freund <andres@anarazel.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Mel Gorman
|
4741526b83 |
mm, page_alloc: restore the original nodemask if the fast path allocation failed
The page allocator fast path uses either the requested nodemask or cpuset_current_mems_allowed if cpusets are enabled. If the allocation context allows watermarks to be ignored then it can also ignore memory policies. However, on entering the allocator slowpath the nodemask may still be cpuset_current_mems_allowed and the policies are enforced. This patch resets the nodemask appropriately before entering the slowpath. Link: http://lkml.kernel.org/r/20160504143628.GU2858@techsingularity.net Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Cc: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Vlastimil Babka
|
4e6118016e |
mm, page_alloc: uninline the bad page part of check_new_page()
Bad pages should be rare so the code handling them doesn't need to be inline for performance reasons. Put it to separate function which returns void. This also assumes that the initial page_expected_state() result will match the result of the thorough check, i.e. the page doesn't become "good" in the meanwhile. This matches the same expectations already in place in free_pages_check(). !DEBUG_VM bloat-o-meter: add/remove: 1/0 grow/shrink: 0/1 up/down: 134/-274 (-140) function old new delta check_new_page_bad - 134 +134 get_page_from_freelist 3468 3194 -274 Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
|
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Mel Gorman
|
e2769dbdc5 |
mm, page_alloc: don't duplicate code in free_pcp_prepare
The new free_pcp_prepare() function shares a lot of code with free_pages_prepare(), which makes this a maintenance risk when some future patch modifies only one of them. We should be able to achieve the same effect (skipping free_pages_check() from !DEBUG_VM configs) by adding a parameter to free_pages_prepare() and making it inline, so the checks (and the order != 0 parts) are eliminated from the call from free_pcp_prepare(). !DEBUG_VM: bloat-o-meter reports no difference, as my gcc was already inlining free_pages_prepare() and the elimination seems to work as expected DEBUG_VM bloat-o-meter: add/remove: 0/1 grow/shrink: 2/0 up/down: 1035/-778 (257) function old new delta __free_pages_ok 297 1060 +763 free_hot_cold_page 480 752 +272 free_pages_prepare 778 - -778 Here inlining didn't occur before, and added some code, but it's ok for a debug option. [akpm@linux-foundation.org: fix build] Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Mel Gorman
|
479f854a20 |
mm, page_alloc: defer debugging checks of pages allocated from the PCP
Every page allocated checks a number of page fields for validity. This
catches corruption bugs of pages that are already freed but it is
expensive. This patch weakens the debugging check by checking PCP pages
only when the PCP lists are being refilled. All compound pages are
checked. This potentially avoids debugging checks entirely if the PCP
lists are never emptied and refilled so some corruption issues may be
missed. Full checking requires DEBUG_VM.
With the two deferred debugging patches applied, the impact to a page
allocator microbenchmark is
4.6.0-rc3 4.6.0-rc3
inline-v3r6 deferalloc-v3r7
Min alloc-odr0-1 344.00 ( 0.00%) 317.00 ( 7.85%)
Min alloc-odr0-2 248.00 ( 0.00%) 231.00 ( 6.85%)
Min alloc-odr0-4 209.00 ( 0.00%) 192.00 ( 8.13%)
Min alloc-odr0-8 181.00 ( 0.00%) 166.00 ( 8.29%)
Min alloc-odr0-16 168.00 ( 0.00%) 154.00 ( 8.33%)
Min alloc-odr0-32 161.00 ( 0.00%) 148.00 ( 8.07%)
Min alloc-odr0-64 158.00 ( 0.00%) 145.00 ( 8.23%)
Min alloc-odr0-128 156.00 ( 0.00%) 143.00 ( 8.33%)
Min alloc-odr0-256 168.00 ( 0.00%) 154.00 ( 8.33%)
Min alloc-odr0-512 178.00 ( 0.00%) 167.00 ( 6.18%)
Min alloc-odr0-1024 186.00 ( 0.00%) 174.00 ( 6.45%)
Min alloc-odr0-2048 192.00 ( 0.00%) 180.00 ( 6.25%)
Min alloc-odr0-4096 198.00 ( 0.00%) 184.00 ( 7.07%)
Min alloc-odr0-8192 200.00 ( 0.00%) 188.00 ( 6.00%)
Min alloc-odr0-16384 201.00 ( 0.00%) 188.00 ( 6.47%)
Min free-odr0-1 189.00 ( 0.00%) 180.00 ( 4.76%)
Min free-odr0-2 132.00 ( 0.00%) 126.00 ( 4.55%)
Min free-odr0-4 104.00 ( 0.00%) 99.00 ( 4.81%)
Min free-odr0-8 90.00 ( 0.00%) 85.00 ( 5.56%)
Min free-odr0-16 84.00 ( 0.00%) 80.00 ( 4.76%)
Min free-odr0-32 80.00 ( 0.00%) 76.00 ( 5.00%)
Min free-odr0-64 78.00 ( 0.00%) 74.00 ( 5.13%)
Min free-odr0-128 77.00 ( 0.00%) 73.00 ( 5.19%)
Min free-odr0-256 94.00 ( 0.00%) 91.00 ( 3.19%)
Min free-odr0-512 108.00 ( 0.00%) 112.00 ( -3.70%)
Min free-odr0-1024 115.00 ( 0.00%) 118.00 ( -2.61%)
Min free-odr0-2048 120.00 ( 0.00%) 125.00 ( -4.17%)
Min free-odr0-4096 123.00 ( 0.00%) 129.00 ( -4.88%)
Min free-odr0-8192 126.00 ( 0.00%) 130.00 ( -3.17%)
Min free-odr0-16384 126.00 ( 0.00%) 131.00 ( -3.97%)
Note that the free paths for large numbers of pages is impacted as the
debugging cost gets shifted into that path when the page data is no
longer necessarily cache-hot.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Mel Gorman
|
4db7548ccb |
mm, page_alloc: defer debugging checks of freed pages until a PCP drain
Every page free checks a number of page fields for validity. This catches premature frees and corruptions but it is also expensive. This patch weakens the debugging check by checking PCP pages at the time they are drained from the PCP list. This will trigger the bug but the site that freed the corrupt page will be lost. To get the full context, a kernel rebuild with DEBUG_VM is necessary. [akpm@linux-foundation.org: fix build] Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Vlastimil Babka
|
002f290627 |
cpuset: use static key better and convert to new API
An important function for cpusets is cpuset_node_allowed(), which
optimizes on the fact if there's a single root CPU set, it must be
trivially allowed. But the check "nr_cpusets() <= 1" doesn't use the
cpusets_enabled_key static key the right way where static keys eliminate
branching overhead with jump labels.
This patch converts it so that static key is used properly. It's also
switched to the new static key API and the checking functions are
converted to return bool instead of int. We also provide a new variant
__cpuset_zone_allowed() which expects that the static key check was
already done and they key was enabled. This is needed for
get_page_from_freelist() where we want to also avoid the relatively
slower check when ALLOC_CPUSET is not set in alloc_flags.
The impact on the page allocator microbenchmark is less than expected
but the cleanup in itself is worthwhile.
4.6.0-rc2 4.6.0-rc2
multcheck-v1r20 cpuset-v1r20
Min alloc-odr0-1 348.00 ( 0.00%) 348.00 ( 0.00%)
Min alloc-odr0-2 254.00 ( 0.00%) 254.00 ( 0.00%)
Min alloc-odr0-4 213.00 ( 0.00%) 213.00 ( 0.00%)
Min alloc-odr0-8 186.00 ( 0.00%) 183.00 ( 1.61%)
Min alloc-odr0-16 173.00 ( 0.00%) 171.00 ( 1.16%)
Min alloc-odr0-32 166.00 ( 0.00%) 163.00 ( 1.81%)
Min alloc-odr0-64 162.00 ( 0.00%) 159.00 ( 1.85%)
Min alloc-odr0-128 160.00 ( 0.00%) 157.00 ( 1.88%)
Min alloc-odr0-256 169.00 ( 0.00%) 166.00 ( 1.78%)
Min alloc-odr0-512 180.00 ( 0.00%) 180.00 ( 0.00%)
Min alloc-odr0-1024 188.00 ( 0.00%) 187.00 ( 0.53%)
Min alloc-odr0-2048 194.00 ( 0.00%) 193.00 ( 0.52%)
Min alloc-odr0-4096 199.00 ( 0.00%) 198.00 ( 0.50%)
Min alloc-odr0-8192 202.00 ( 0.00%) 201.00 ( 0.50%)
Min alloc-odr0-16384 203.00 ( 0.00%) 202.00 ( 0.49%)
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Zefan Li <lizefan@huawei.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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|
|
Mel Gorman
|
0b423ca22f |
mm, page_alloc: inline pageblock lookup in page free fast paths
The function call overhead of get_pfnblock_flags_mask() is measurable in the page free paths. This patch uses an inlined version that is faster. Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
|
|
Mel Gorman
|
e5b31ac2ca |
mm, page_alloc: remove unnecessary variable from free_pcppages_bulk
The original count is never reused so it can be removed. Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
|
|
Mel Gorman
|
da838d4fcb |
mm, page_alloc: pull out side effects from free_pages_check
Check without side-effects should be easier to maintain. It also removes the duplicated cpupid and flags reset done in !DEBUG_VM variant of both free_pcp_prepare() and then bulkfree_pcp_prepare(). Finally, it enables the next patch. It shouldn't result in new branches, thanks to inlining of the check. !DEBUG_VM bloat-o-meter: add/remove: 0/0 grow/shrink: 0/2 up/down: 0/-27 (-27) function old new delta __free_pages_ok 748 739 -9 free_pcppages_bulk 1403 1385 -18 DEBUG_VM: add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-28 (-28) function old new delta free_pages_prepare 806 778 -28 This is also slightly faster because cpupid information is not set on tail pages so we can avoid resets there. Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
|
|
Mel Gorman
|
bb552ac6c6 |
mm, page_alloc: un-inline the bad part of free_pages_check
From: Vlastimil Babka <vbabka@suse.cz> !DEBUG_VM size and bloat-o-meter: add/remove: 1/0 grow/shrink: 0/2 up/down: 124/-370 (-246) function old new delta free_pages_check_bad - 124 +124 free_pcppages_bulk 1288 1171 -117 __free_pages_ok 948 695 -253 DEBUG_VM: add/remove: 1/0 grow/shrink: 0/1 up/down: 124/-214 (-90) function old new delta free_pages_check_bad - 124 +124 free_pages_prepare 1112 898 -214 [akpm@linux-foundation.org: fix whitespace] Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
|
|
Mel Gorman
|
7bfec6f47b |
mm, page_alloc: check multiple page fields with a single branch
Every page allocated or freed is checked for sanity to avoid corruptions
that are difficult to detect later. A bad page could be due to a number
of fields. Instead of using multiple branches, this patch combines
multiple fields into a single branch. A detailed check is only
necessary if that check fails.
4.6.0-rc2 4.6.0-rc2
initonce-v1r20 multcheck-v1r20
Min alloc-odr0-1 359.00 ( 0.00%) 348.00 ( 3.06%)
Min alloc-odr0-2 260.00 ( 0.00%) 254.00 ( 2.31%)
Min alloc-odr0-4 214.00 ( 0.00%) 213.00 ( 0.47%)
Min alloc-odr0-8 186.00 ( 0.00%) 186.00 ( 0.00%)
Min alloc-odr0-16 173.00 ( 0.00%) 173.00 ( 0.00%)
Min alloc-odr0-32 165.00 ( 0.00%) 166.00 ( -0.61%)
Min alloc-odr0-64 162.00 ( 0.00%) 162.00 ( 0.00%)
Min alloc-odr0-128 161.00 ( 0.00%) 160.00 ( 0.62%)
Min alloc-odr0-256 170.00 ( 0.00%) 169.00 ( 0.59%)
Min alloc-odr0-512 181.00 ( 0.00%) 180.00 ( 0.55%)
Min alloc-odr0-1024 190.00 ( 0.00%) 188.00 ( 1.05%)
Min alloc-odr0-2048 196.00 ( 0.00%) 194.00 ( 1.02%)
Min alloc-odr0-4096 202.00 ( 0.00%) 199.00 ( 1.49%)
Min alloc-odr0-8192 205.00 ( 0.00%) 202.00 ( 1.46%)
Min alloc-odr0-16384 205.00 ( 0.00%) 203.00 ( 0.98%)
Again, the benefit is marginal but avoiding excessive branches is
important. Ideally the paths would not have to check these conditions
at all but regrettably abandoning the tests would make use-after-free
bugs much harder to detect.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
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Mel Gorman
|
93ea9964d1 |
mm, page_alloc: remove field from alloc_context
The classzone_idx can be inferred from preferred_zoneref so remove the unnecessary field and save stack space. Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Mel Gorman
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c33d6c06f6 |
mm, page_alloc: avoid looking up the first zone in a zonelist twice
The allocator fast path looks up the first usable zone in a zonelist and
then get_page_from_freelist does the same job in the zonelist iterator.
This patch preserves the necessary information.
4.6.0-rc2 4.6.0-rc2
fastmark-v1r20 initonce-v1r20
Min alloc-odr0-1 364.00 ( 0.00%) 359.00 ( 1.37%)
Min alloc-odr0-2 262.00 ( 0.00%) 260.00 ( 0.76%)
Min alloc-odr0-4 214.00 ( 0.00%) 214.00 ( 0.00%)
Min alloc-odr0-8 186.00 ( 0.00%) 186.00 ( 0.00%)
Min alloc-odr0-16 173.00 ( 0.00%) 173.00 ( 0.00%)
Min alloc-odr0-32 165.00 ( 0.00%) 165.00 ( 0.00%)
Min alloc-odr0-64 161.00 ( 0.00%) 162.00 ( -0.62%)
Min alloc-odr0-128 159.00 ( 0.00%) 161.00 ( -1.26%)
Min alloc-odr0-256 168.00 ( 0.00%) 170.00 ( -1.19%)
Min alloc-odr0-512 180.00 ( 0.00%) 181.00 ( -0.56%)
Min alloc-odr0-1024 190.00 ( 0.00%) 190.00 ( 0.00%)
Min alloc-odr0-2048 196.00 ( 0.00%) 196.00 ( 0.00%)
Min alloc-odr0-4096 202.00 ( 0.00%) 202.00 ( 0.00%)
Min alloc-odr0-8192 206.00 ( 0.00%) 205.00 ( 0.49%)
Min alloc-odr0-16384 206.00 ( 0.00%) 205.00 ( 0.49%)
The benefit is negligible and the results are within the noise but each
cycle counts.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Mel Gorman
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48ee5f3696 |
mm, page_alloc: shortcut watermark checks for order-0 pages
Watermarks have to be checked on every allocation including the number
of pages being allocated and whether reserves can be accessed. The
reserves only matter if memory is limited and the free_pages adjustment
only applies to high-order pages. This patch adds a shortcut for
order-0 pages that avoids numerous calculations if there is plenty of
free memory yielding the following performance difference in a page
allocator microbenchmark;
4.6.0-rc2 4.6.0-rc2
optfair-v1r20 fastmark-v1r20
Min alloc-odr0-1 380.00 ( 0.00%) 364.00 ( 4.21%)
Min alloc-odr0-2 273.00 ( 0.00%) 262.00 ( 4.03%)
Min alloc-odr0-4 227.00 ( 0.00%) 214.00 ( 5.73%)
Min alloc-odr0-8 196.00 ( 0.00%) 186.00 ( 5.10%)
Min alloc-odr0-16 183.00 ( 0.00%) 173.00 ( 5.46%)
Min alloc-odr0-32 173.00 ( 0.00%) 165.00 ( 4.62%)
Min alloc-odr0-64 169.00 ( 0.00%) 161.00 ( 4.73%)
Min alloc-odr0-128 169.00 ( 0.00%) 159.00 ( 5.92%)
Min alloc-odr0-256 180.00 ( 0.00%) 168.00 ( 6.67%)
Min alloc-odr0-512 190.00 ( 0.00%) 180.00 ( 5.26%)
Min alloc-odr0-1024 198.00 ( 0.00%) 190.00 ( 4.04%)
Min alloc-odr0-2048 204.00 ( 0.00%) 196.00 ( 3.92%)
Min alloc-odr0-4096 209.00 ( 0.00%) 202.00 ( 3.35%)
Min alloc-odr0-8192 213.00 ( 0.00%) 206.00 ( 3.29%)
Min alloc-odr0-16384 214.00 ( 0.00%) 206.00 ( 3.74%)
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Mel Gorman
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305347550b |
mm, page_alloc: reduce cost of fair zone allocation policy retry
The fair zone allocation policy is not without cost but it can be
reduced slightly. This patch removes an unnecessary local variable,
checks the likely conditions of the fair zone policy first, uses a bool
instead of a flags check and falls through when a remote node is
encountered instead of doing a full restart. The benefit is marginal
but it's there
4.6.0-rc2 4.6.0-rc2
decstat-v1r20 optfair-v1r20
Min alloc-odr0-1 377.00 ( 0.00%) 380.00 ( -0.80%)
Min alloc-odr0-2 273.00 ( 0.00%) 273.00 ( 0.00%)
Min alloc-odr0-4 226.00 ( 0.00%) 227.00 ( -0.44%)
Min alloc-odr0-8 196.00 ( 0.00%) 196.00 ( 0.00%)
Min alloc-odr0-16 183.00 ( 0.00%) 183.00 ( 0.00%)
Min alloc-odr0-32 175.00 ( 0.00%) 173.00 ( 1.14%)
Min alloc-odr0-64 172.00 ( 0.00%) 169.00 ( 1.74%)
Min alloc-odr0-128 170.00 ( 0.00%) 169.00 ( 0.59%)
Min alloc-odr0-256 183.00 ( 0.00%) 180.00 ( 1.64%)
Min alloc-odr0-512 191.00 ( 0.00%) 190.00 ( 0.52%)
Min alloc-odr0-1024 199.00 ( 0.00%) 198.00 ( 0.50%)
Min alloc-odr0-2048 204.00 ( 0.00%) 204.00 ( 0.00%)
Min alloc-odr0-4096 210.00 ( 0.00%) 209.00 ( 0.48%)
Min alloc-odr0-8192 213.00 ( 0.00%) 213.00 ( 0.00%)
Min alloc-odr0-16384 214.00 ( 0.00%) 214.00 ( 0.00%)
The benefit is marginal at best but one of the most important benefits,
avoiding a second search when falling back to another node is not
triggered by this particular test so the benefit for some corner cases
is understated.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Mel Gorman
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4fcb097117 |
mm, page_alloc: shorten the page allocator fast path
The page allocator fast path checks page multiple times unnecessarily. This patch avoids all the slowpath checks if the first allocation attempt succeeds. Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Mel Gorman
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3777999dd4 |
mm, page_alloc: check once if a zone has isolated pageblocks
When bulk freeing pages from the per-cpu lists the zone is checked for isolated pageblocks on every release. This patch checks it once per drain. [mgorman@techsingularity.net: fix locking radce, per Vlastimil] Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Mel Gorman
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83d4ca8148 |
mm, page_alloc: move __GFP_HARDWALL modifications out of the fastpath
__GFP_HARDWALL only has meaning in the context of cpusets but the fast
path always applies the flag on the first attempt. Move the
manipulations into the cpuset paths where they will be masked by a
static branch in the common case.
With the other micro-optimisations in this series combined, the impact
on a page allocator microbenchmark is
4.6.0-rc2 4.6.0-rc2
decstat-v1r20 micro-v1r20
Min alloc-odr0-1 381.00 ( 0.00%) 377.00 ( 1.05%)
Min alloc-odr0-2 275.00 ( 0.00%) 273.00 ( 0.73%)
Min alloc-odr0-4 229.00 ( 0.00%) 226.00 ( 1.31%)
Min alloc-odr0-8 199.00 ( 0.00%) 196.00 ( 1.51%)
Min alloc-odr0-16 186.00 ( 0.00%) 183.00 ( 1.61%)
Min alloc-odr0-32 179.00 ( 0.00%) 175.00 ( 2.23%)
Min alloc-odr0-64 174.00 ( 0.00%) 172.00 ( 1.15%)
Min alloc-odr0-128 172.00 ( 0.00%) 170.00 ( 1.16%)
Min alloc-odr0-256 181.00 ( 0.00%) 183.00 ( -1.10%)
Min alloc-odr0-512 193.00 ( 0.00%) 191.00 ( 1.04%)
Min alloc-odr0-1024 201.00 ( 0.00%) 199.00 ( 1.00%)
Min alloc-odr0-2048 206.00 ( 0.00%) 204.00 ( 0.97%)
Min alloc-odr0-4096 212.00 ( 0.00%) 210.00 ( 0.94%)
Min alloc-odr0-8192 215.00 ( 0.00%) 213.00 ( 0.93%)
Min alloc-odr0-16384 216.00 ( 0.00%) 214.00 ( 0.93%)
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Mel Gorman
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5bb1b16975 |
mm, page_alloc: remove unnecessary initialisation from __alloc_pages_nodemask()
page is guaranteed to be set before it is read with or without the initialisation. [akpm@linux-foundation.org: fix warning] Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Mel Gorman
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be06af002f |
mm, page_alloc: remove unnecessary initialisation in get_page_from_freelist
Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Mel Gorman
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4dfa6cd8fd |
mm, page_alloc: remove unnecessary local variable in get_page_from_freelist
zonelist here is a copy of a struct field that is used once. Ditch it. Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Mel Gorman
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fa379b9586 |
mm, page_alloc: convert nr_fair_skipped to bool
The number of zones skipped to a zone expiring its fair zone allocation quota is irrelevant. Convert to bool. Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Mel Gorman
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c603844bdc |
mm, page_alloc: convert alloc_flags to unsigned
alloc_flags is a bitmask of flags but it is signed which does not necessarily generate the best code depending on the compiler. Even without an impact, it makes more sense that this be unsigned. Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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Mel Gorman
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f75fb889d1 |
mm, page_alloc: avoid unnecessary zone lookups during pageblock operations
Pageblocks have an associated bitmap to store migrate types and whether the pageblock should be skipped during compaction. The bitmap may be associated with a memory section or a zone but the zone is looked up unconditionally. The compiler should optimise this away automatically so this is a cosmetic patch only in many cases. Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |