mm: numa: Use a two-stage filter to restrict pages being migrated for unlikely task<->node relationships

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Note: This two-stage filter was taken directly from the sched/numa patch
	"sched, numa, mm: Add the scanning page fault machinery" but is
	only a partial extraction. As the end result is not necessarily
	recognisable, the signed-offs-by had to be removed. Will be added
	back if requested.

While it is desirable that all threads in a process run on its home
node, this is not always possible or necessary. There may be more
threads than exist within the node or the node might over-subscribed
with unrelated processes.

This can cause a situation whereby a page gets migrated off its home
node because the threads clearing pte_numa were running off-node. This
patch uses page->last_nid to build a two-stage filter before pages get
migrated to avoid problems with short or unlikely task<->node
relationships.

Signed-off-by: Mel Gorman <mgorman@suse.de>

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This commit is contained in:

Mel Gorman 2012-11-12 09:17:07 +00:00

parent bac0382c6a

commit e42c8ff299

1 changed files with 29 additions and 1 deletions

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mm/mempolicy.c

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