Subject: + mm-thp-avoid-excessive-compaction-latency-during-fault.patch added to -mm tree
To: rientjes@xxxxxxxxxx,gthelen@xxxxxxxxxx,mgorman@xxxxxxx,n-horiguchi@xxxxxxxxxxxxx,vbabka@xxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Wed, 07 May 2014 14:20:51 -0700
The patch titled
Subject: mm, thp: avoid excessive compaction latency during fault
has been added to the -mm tree. Its filename is
mm-thp-avoid-excessive-compaction-latency-during-fault.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-thp-avoid-excessive-compaction-latency-during-fault.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-thp-avoid-excessive-compaction-latency-during-fault.patch
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------------------------------------------------------
From: David Rientjes <rientjes@xxxxxxxxxx>
Subject: mm, thp: avoid excessive compaction latency during fault
Synchronous memory compaction can be very expensive: it can iterate an
enormous amount of memory without aborting, constantly rescheduling,
waiting on page locks and lru_lock, etc, if a pageblock cannot be
defragmented.
Unfortunately, it's too expensive for transparent hugepage page faults and
it's much better to simply fallback to pages. On 128GB machines, we find
that synchronous memory compaction can take O(seconds) for a single thp
fault.
Now that async compaction remembers where it left off without strictly
relying on sync compaction, this makes thp allocations best-effort without
causing egregious latency during fault. We still need to retry async
compaction after reclaim, but this won't stall for seconds.
Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>
Acked-by: Mel Gorman <mgorman@xxxxxxx>
Cc: Greg Thelen <gthelen@xxxxxxxxxx>
Cc: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)
diff -puN mm/page_alloc.c~mm-thp-avoid-excessive-compaction-latency-during-fault mm/page_alloc.c
--- a/mm/page_alloc.c~mm-thp-avoid-excessive-compaction-latency-during-fault
+++ a/mm/page_alloc.c
@@ -2578,7 +2578,17 @@ rebalance:
&did_some_progress);
if (page)
goto got_pg;
- migration_mode = MIGRATE_SYNC_LIGHT;
+
+ if (gfp_mask & __GFP_NO_KSWAPD) {
+ /*
+ * Khugepaged is allowed to try MIGRATE_SYNC_LIGHT, the latency
+ * of this allocation isn't critical. Everything else, however,
+ * should only be allowed to do MIGRATE_ASYNC to avoid excessive
+ * stalls during fault.
+ */
+ if ((current->flags & (PF_KTHREAD | PF_KSWAPD)) == PF_KTHREAD)
+ migration_mode = MIGRATE_SYNC_LIGHT;
+ }
/*
* If compaction is deferred for high-order allocations, it is because
_
Patches currently in -mm which might be from rientjes@xxxxxxxxxx are
mm-memcontrol-remove-hierarchy-restrictions-for-swappiness-and-oom_control.patch
mm-memcontrol-remove-hierarchy-restrictions-for-swappiness-and-oom_control-fix.patch
hugetlb-prep_compound_gigantic_page-drop-__init-marker.patch
hugetlb-add-hstate_is_gigantic.patch
hugetlb-update_and_free_page-dont-clear-pg_reserved-bit.patch
hugetlb-move-helpers-up-in-the-file.patch
hugetlb-add-support-for-gigantic-page-allocation-at-runtime.patch
mem-hotplug-implement-get-put_online_mems.patch
slab-get_online_mems-for-kmem_cache_createdestroyshrink.patch
mm-debug-make-bad_range-output-more-usable-and-readable.patch
memcg-do-not-hang-on-oom-when-killed-by-userspace-oom-access-to-memory-reserves.patch
mm-migration-add-destination-page-freeing-callback.patch
mm-compaction-return-failed-migration-target-pages-back-to-freelist.patch
mm-compaction-add-per-zone-migration-pfn-cache-for-async-compaction.patch
mm-compaction-embed-migration-mode-in-compact_control.patch
mm-thp-avoid-excessive-compaction-latency-during-fault.patch
mm-compaction-terminate-async-compaction-when-rescheduling.patch
mm-utilc-add-kstrimdup.patch
linux-next.patch
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