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authorMel Gorman <mgorman@suse.de>2011-10-31 17:09:33 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2011-10-31 17:30:50 -0700
commite0c23279c9f800c403f37511484d9014ac83adec (patch)
tree9dcf058d3d1c691328ea5839dfe9c340e47ee3fa /mm
parente0887c19b2daa140f20ca8104bdc5740f39dbb86 (diff)
downloadlinux-stericsson-e0c23279c9f800c403f37511484d9014ac83adec.tar.gz
vmscan: abort reclaim/compaction if compaction can proceed
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>
Diffstat (limited to 'mm')
-rw-r--r--mm/vmscan.c32
1 files changed, 21 insertions, 11 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 7e0f05797388..a90c603a8d02 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2103,14 +2103,19 @@ restart:
*
* 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