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mm, vmscan: wake up all pfmemalloc-throttled processes at once 

Kswapd in balance_pgdate() currently uses wake_up() on processes waiting
in throttle_direct_reclaim(), which only wakes up a single process.  This
might leave processes waiting for longer than necessary, until the check
is reached in the next loop iteration.  Processes might also be left
waiting if zone was fully balanced in single iteration.  Note that the
comment in balance_pgdat() also says "Wake them", so waking up a single
process does not seem intentional.

Thus, replace wake_up() with wake_up_all().

Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Vladimir Davydov <vdavydov@parallels.com>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Vlastimil Babka 2015-02-11 15:25:12 -08:00 committed by Linus Torvalds
parent 44628d9755
commit cfc5115579
1 changed files with 1 additions and 1 deletions
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2
mm/vmscan.c
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@ -3175,7 +3175,7 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, int order,
*/
if (waitqueue_active(&pgdat->pfmemalloc_wait) &&
pfmemalloc_watermark_ok(pgdat))
wake_up(&pgdat->pfmemalloc_wait);
wake_up_all(&pgdat->pfmemalloc_wait);
/*
* Fragmentation may mean that the system cannot be rebalanced