The patch titled
Subject: mm, compaction: do not direct compact remote memory
has been added to the -mm tree. Its filename is
mm-compaction-do-not-direct-compact-remote-memory.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-compaction-do-not-direct-compact-remote-memory.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-compaction-do-not-direct-compact-remote-memory.patch
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------------------------------------------------------
From: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Subject: mm, compaction: do not direct compact remote memory
Remote compaction is expensive and possibly counter-productive. Locality
is expected to often have better performance characteristics than remote
high-order pages. For small allocations, it's expected that locality is
generally required or fallbacks are possible. For larger allocations such
as THP, they are forbidden at the time of writing but if __GFP_THISNODE is
ever removed, then it would still be preferable to fallback to small local
base pages over remote THP in the general case. kcompactd is still woken
via kswapd so compaction happens eventually.
While this patch potentially has both positive and negative effects, it is
best to avoid the possibility of remote compaction given the cost relative
to any potential benefit.
Link: http://lkml.kernel.org/r/20190104125011.16071-26-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-direct-compact-remote-memory
+++ a/mm/compaction.c
@@ -2348,6 +2348,16 @@ enum compact_result try_to_compact_pages
continue;
}
+ /*
+ * Do not compact remote memory. It's expensive and high-order
+ * small allocations are expected to prefer or require local
+ * memory. Similarly, larger requests such as THP can fallback
+ * to base pages in preference to remote huge pages if
+ * __GFP_THISNODE is not specified
+ */
+ if (zone_to_nid(zone) != zone_to_nid(ac->preferred_zoneref->zone))
+ continue;
+
status = compact_zone_order(zone, order, gfp_mask, prio,
alloc_flags, ac_classzone_idx(ac), capture);
rc = max(status, rc);
_
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
