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vmscan: abort reclaim/compaction if compaction can proceed

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If compaction can proceed, shrink_zones() stops doing any work but its
callers still call shrink_slab() which raises the priority and potentially
sleeps.  This is unnecessary and wasteful so this patch aborts direct
reclaim/compaction entirely if compaction can proceed.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Acked-by: Johannes Weiner <jweiner@redhat.com>
Cc: Josh Boyer <jwboyer@redhat.com>
Cc: Andrea Arcangeli <aarcange@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:
Mel Gorman 2011-10-31 17:09:33 -07:00 committed by Linus Torvalds
parent e0887c19b2
commit e0c23279c9
1 changed files with 21 additions and 11 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

32
mm/vmscan.c
View file

@ -2103,14 +2103,19 @@ static void shrink_zone(int priority, struct zone *zone,
*
* If a zone is deemed to be full of pinned pages then just give it a light
* scan then give up on it.
*
* This function returns true if a zone is being reclaimed for a costly
* high-order allocation and compaction is either ready to begin or deferred.
* This indicates to the caller that it should retry the allocation or fail.
*/
static void shrink_zones(int priority, struct zonelist *zonelist,
static bool shrink_zones(int priority, struct zonelist *zonelist,
struct scan_control *sc)
{
struct zoneref *z;
struct zone *zone;
unsigned long nr_soft_reclaimed;
unsigned long nr_soft_scanned;
bool should_abort_reclaim = false;
for_each_zone_zonelist_nodemask(zone, z, zonelist,
gfp_zone(sc->gfp_mask), sc->nodemask) {
@ -2127,19 +2132,20 @@ static void shrink_zones(int priority, struct zonelist *zonelist,
continue; /* Let kswapd poll it */
if (COMPACTION_BUILD) {
/*
* If we already have plenty of memory
* free for compaction, don't free any
* more. Even though compaction is
* invoked for any non-zero order,
* only frequent costly order
* reclamation is disruptive enough to
* become a noticable problem, like
* transparent huge page allocations.
* If we already have plenty of memory free for
* compaction in this zone, don't free any more.
* Even though compaction is invoked for any
* non-zero order, only frequent costly order
* reclamation is disruptive enough to become a
* noticable problem, like transparent huge page
* allocations.
*/
if (sc->order > PAGE_ALLOC_COSTLY_ORDER &&
(compaction_suitable(zone, sc->order) ||
compaction_deferred(zone)))
compaction_deferred(zone))) {
should_abort_reclaim = true;
continue;
}
}
/*
* This steals pages from memory cgroups over softlimit
@ -2158,6 +2164,8 @@ static void shrink_zones(int priority, struct zonelist *zonelist,
shrink_zone(priority, zone, sc);
}
return should_abort_reclaim;
}
static bool zone_reclaimable(struct zone *zone)
@ -2222,7 +2230,9 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
sc->nr_scanned = 0;
if (!priority)
disable_swap_token(sc->mem_cgroup);
shrink_zones(priority, zonelist, sc);
if (shrink_zones(priority, zonelist, sc))
break;
/*
* Don't shrink slabs when reclaiming memory from
* over limit cgroups