The patch titled
Subject: mm, compaction: do not consider a need to reschedule as contention
has been added to the -mm tree. Its filename is
mm-compaction-do-not-consider-a-need-to-reschedule-as-contention.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-compaction-do-not-consider-a-need-to-reschedule-as-contention.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-compaction-do-not-consider-a-need-to-reschedule-as-contention.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Subject: mm, compaction: do not consider a need to reschedule as contention
Scanning on large machines can take a considerable length of time and
eventually need to be rescheduled. This is treated as an abort event but
that's not appropriate as the attempt is likely to be retried after making
numerous checks and taking another cycle through the page allocator. This
patch will check the need to reschedule if necessary but continue the
scanning.
The main benefit is reduced scanning when compaction is taking a long time
or the machine is over-saturated. It also avoids an unnecessary exit of
compaction that ends up being retried by the page allocator in the outer
loop.
4.20.0 4.20.0
synccached-v2r15 noresched-v2r15
Amean fault-both-3 2655.55 ( 0.00%) 2736.50 ( -3.05%)
Amean fault-both-5 4580.67 ( 0.00%) 4133.70 ( 9.76%)
Amean fault-both-7 5740.50 ( 0.00%) 5738.61 ( 0.03%)
Amean fault-both-12 9237.55 ( 0.00%) 9392.82 ( -1.68%)
Amean fault-both-18 12899.51 ( 0.00%) 13257.15 ( -2.77%)
Amean fault-both-24 16342.47 ( 0.00%) 16859.44 ( -3.16%)
Amean fault-both-30 20394.26 ( 0.00%) 16249.30 * 20.32%*
Amean fault-both-32 17450.76 ( 0.00%) 14904.71 * 14.59%*
Link: http://lkml.kernel.org/r/20190104125011.16071-20-mgorman@xxxxxxxxxxxxxxxxxxx
Signed-off-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Huang Ying <ying.huang@xxxxxxxxx>
Cc: Kirill A. Shutemov <kirill@xxxxxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
--- a/mm/compaction.c~mm-compaction-do-not-consider-a-need-to-reschedule-as-contention
+++ a/mm/compaction.c
@@ -398,19 +398,11 @@ static bool compact_lock_irqsave(spinloc
return true;
}
-/*
- * Aside from avoiding lock contention, compaction also periodically checks
- * need_resched() and records async compaction as contended if necessary.
- */
+/* Avoid soft-lockups due to long scan times */
static inline void compact_check_resched(struct compact_control *cc)
{
- /* async compaction aborts if contended */
- if (need_resched()) {
- if (cc->mode == MIGRATE_ASYNC)
- cc->contended = true;
-
+ if (need_resched())
cond_resched();
- }
}
/*
_
Patches currently in -mm which might be from mgorman@xxxxxxxxxxxxxxxxxxx are
mm-page_alloc-do-not-wake-kswapd-with-zone-lock-held.patch
mm-compaction-shrink-compact_control.patch
mm-compaction-rearrange-compact_control.patch
mm-compaction-remove-last_migrated_pfn-from-compact_control.patch
mm-compaction-remove-unnecessary-zone-parameter-in-some-instances.patch
mm-compaction-rename-map_pages-to-split_map_pages.patch
mm-compaction-skip-pageblocks-with-reserved-pages.patch
mm-migrate-immediately-fail-migration-of-a-page-with-no-migration-handler.patch
mm-compaction-always-finish-scanning-of-a-full-pageblock.patch
mm-compaction-use-the-page-allocator-bulk-free-helper-for-lists-of-pages.patch
mm-compaction-ignore-the-fragmentation-avoidance-boost-for-isolation-and-compaction.patch
mm-compaction-use-free-lists-to-quickly-locate-a-migration-source.patch
mm-compaction-keep-migration-source-private-to-a-single-compaction-instance.patch
mm-compaction-use-free-lists-to-quickly-locate-a-migration-target.patch
mm-compaction-avoid-rescanning-the-same-pageblock-multiple-times.patch
mm-compaction-finish-pageblock-scanning-on-contention.patch
mm-compaction-check-early-for-huge-pages-encountered-by-the-migration-scanner.patch
mm-compaction-keep-cached-migration-pfns-synced-for-unusable-pageblocks.patch
mm-compaction-rework-compact_should_abort-as-compact_check_resched.patch
mm-compaction-do-not-consider-a-need-to-reschedule-as-contention.patch
mm-compaction-reduce-unnecessary-skipping-of-migration-target-scanner.patch
mm-compaction-round-robin-the-order-while-searching-the-free-lists-for-a-target.patch
mm-compaction-sample-pageblocks-for-free-pages.patch
mm-compaction-be-selective-about-what-pageblocks-to-clear-skip-hints.patch
mm-compaction-capture-a-page-under-direct-compaction.patch
mm-compaction-do-not-direct-compact-remote-memory.patch
