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mm: vmscan: check if reclaim should really abort even if compaction_ready() is true for one zone 

If compaction can proceed for a given zone, shrink_zones() does not
reclaim any more pages from it.  After commit [e0c2327: vmscan: abort
reclaim/compaction if compaction can proceed], do_try_to_free_pages()
tries to finish as soon as possible once one zone can compact.

This was intended to prevent slabs being shrunk unnecessarily but there
are side-effects.  One is that a small zone that is ready for compaction
will abort reclaim even if the chances of successfully allocating a THP
from that zone is small.  It also means that reclaim can return too early
even though sc->nr_to_reclaim pages were not reclaimed.

This partially reverts the commit until it is proven that slabs are really
being shrunk unnecessarily but preserves the check to return 1 to avoid
OOM if reclaim was aborted prematurely.

[aarcange@redhat.com: This patch replaces a revert from Andrea]
Signed-off-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: Dave Jones <davej@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Andy Isaacson <adi@hexapodia.org>
Cc: Nai Xia <nai.xia@gmail.com>
Cc: Johannes Weiner <jweiner@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 2012-01-12 17:19:49 -08:00 committed by Linus Torvalds
parent fe4b1b244b
commit 0cee34fd72
1 changed files with 9 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
mm/vmscan.c
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@ -2217,7 +2217,8 @@ static inline bool compaction_ready(struct zone *zone, struct scan_control *sc)
* *
* This function returns true if a zone is being reclaimed for a costly * This function returns true if a zone is being reclaimed for a costly
* high-order allocation and compaction is ready to begin. This indicates to * high-order allocation and compaction is ready to begin. This indicates to
* the caller that it should retry the allocation or fail. * the caller that it should consider retrying the allocation instead of
* further reclaim.
*/ */
static bool shrink_zones(int priority, struct zonelist *zonelist, static bool shrink_zones(int priority, struct zonelist *zonelist,
struct scan_control *sc) struct scan_control *sc)
@ -2226,7 +2227,7 @@ static bool shrink_zones(int priority, struct zonelist *zonelist,
struct zone *zone; struct zone *zone;
unsigned long nr_soft_reclaimed; unsigned long nr_soft_reclaimed;
unsigned long nr_soft_scanned; unsigned long nr_soft_scanned;
bool should_abort_reclaim = false; bool aborted_reclaim = false;
for_each_zone_zonelist_nodemask(zone, z, zonelist, for_each_zone_zonelist_nodemask(zone, z, zonelist,
gfp_zone(sc->gfp_mask), sc->nodemask) { gfp_zone(sc->gfp_mask), sc->nodemask) {
@ -2252,7 +2253,7 @@ static bool shrink_zones(int priority, struct zonelist *zonelist,
* allocations. * allocations.
*/ */
if (compaction_ready(zone, sc)) { if (compaction_ready(zone, sc)) {
should_abort_reclaim = true; aborted_reclaim = true;
continue; continue;
} }
} }
@ -2274,7 +2275,7 @@ static bool shrink_zones(int priority, struct zonelist *zonelist,
shrink_zone(priority, zone, sc); shrink_zone(priority, zone, sc);
} }
return should_abort_reclaim; return aborted_reclaim;
} }
static bool zone_reclaimable(struct zone *zone) static bool zone_reclaimable(struct zone *zone)
@ -2328,7 +2329,7 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
struct zoneref *z; struct zoneref *z;
struct zone *zone; struct zone *zone;
unsigned long writeback_threshold; unsigned long writeback_threshold;
bool should_abort_reclaim; bool aborted_reclaim;
get_mems_allowed(); get_mems_allowed();
delayacct_freepages_start(); delayacct_freepages_start();
@ -2340,9 +2341,7 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
sc->nr_scanned = 0; sc->nr_scanned = 0;
if (!priority) if (!priority)
disable_swap_token(sc->target_mem_cgroup); disable_swap_token(sc->target_mem_cgroup);
should_abort_reclaim = shrink_zones(priority, zonelist, sc); aborted_reclaim = shrink_zones(priority, zonelist, sc);
if (should_abort_reclaim)
break;
/* /*
* Don't shrink slabs when reclaiming memory from * Don't shrink slabs when reclaiming memory from
@ -2409,8 +2408,8 @@ out:
if (oom_killer_disabled) if (oom_killer_disabled)
return 0; return 0;
/* Aborting reclaim to try compaction? don't OOM, then */ /* Aborted reclaim to try compaction? don't OOM, then */
if (should_abort_reclaim) if (aborted_reclaim)
return 1; return 1;
/* top priority shrink_zones still had more to do? don't OOM, then */ /* top priority shrink_zones still had more to do? don't OOM, then */