From c01043c9aa51a63bd01c60e53494ca4a7e994542 Mon Sep 17 00:00:00 2001 From: Mel Gorman Date: Fri, 7 Oct 2011 16:17:23 +0100 Subject: [PATCH 2/2] mm: Abort reclaim/compaction if compaction can proceed If compaction can proceed, shrink_zones() stops doing any work but the callers still shrink_slab(), raises the priority and potentially sleeps. This patch aborts direct reclaim/compaction entirely if compaction can proceed. Signed-off-by: Mel Gorman --- mm/vmscan.c | 20 ++++++++++++++++---- 1 files changed, 16 insertions(+), 4 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index 8c03534..b295a38 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2000,14 +2000,19 @@ 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) { @@ -2025,12 +2030,15 @@ static void shrink_zones(int priority, struct zonelist *zonelist, if (COMPACTION_BUILD) { /* * If we already have plenty of memory free - * for compaction, don't free any more. + * for compaction in this zone , don't free any + * more. */ 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 @@ -2049,6 +2057,8 @@ 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) @@ -2113,7 +2123,9 @@ 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 -- 1.7.6.4