From 66199712e9eef5aede09dbcd9dfff87798a66917 Mon Sep 17 00:00:00 2001 From: Mel Gorman Date: Thu, 12 Jan 2012 17:19:41 -0800 Subject: [PATCH] mm: page allocator: do not call direct reclaim for THP allocations while compaction is deferred If compaction is deferred, direct reclaim is used to try to free enough pages for the allocation to succeed. For small high-orders, this has a reasonable chance of success. However, if the caller has specified __GFP_NO_KSWAPD to limit the disruption to the system, it makes more sense to fail the allocation rather than stall the caller in direct reclaim. This patch skips direct reclaim if compaction is deferred and the caller specifies __GFP_NO_KSWAPD. Async compaction only considers a subset of pages so it is possible for compaction to be deferred prematurely and not enter direct reclaim even in cases where it should. To compensate for this, this patch also defers compaction only if sync compaction failed. Signed-off-by: Mel Gorman Acked-by: Minchan Kim Reviewed-by: Rik van Riel Cc: Andrea Arcangeli Cc: Dave Jones Cc: Jan Kara Cc: Andy Isaacson Cc: Nai Xia Cc: Johannes Weiner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/page_alloc.c | 45 +++++++++++++++++++++++++++++++++++---------- 1 file changed, 35 insertions(+), 10 deletions(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 9404b38bcdc5..cb5723c491f0 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1981,14 +1981,20 @@ static struct page * __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order, struct zonelist *zonelist, enum zone_type high_zoneidx, nodemask_t *nodemask, int alloc_flags, struct zone *preferred_zone, - int migratetype, unsigned long *did_some_progress, - bool sync_migration) + int migratetype, bool sync_migration, + bool *deferred_compaction, + unsigned long *did_some_progress) { struct page *page; - if (!order || compaction_deferred(preferred_zone)) + if (!order) return NULL; + if (compaction_deferred(preferred_zone)) { + *deferred_compaction = true; + return NULL; + } + current->flags |= PF_MEMALLOC; *did_some_progress = try_to_compact_pages(zonelist, order, gfp_mask, nodemask, sync_migration); @@ -2016,7 +2022,13 @@ __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order, * but not enough to satisfy watermarks. */ count_vm_event(COMPACTFAIL); - defer_compaction(preferred_zone); + + /* + * As async compaction considers a subset of pageblocks, only + * defer if the failure was a sync compaction failure. + */ + if (sync_migration) + defer_compaction(preferred_zone); cond_resched(); } @@ -2028,8 +2040,9 @@ static inline struct page * __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order, struct zonelist *zonelist, enum zone_type high_zoneidx, nodemask_t *nodemask, int alloc_flags, struct zone *preferred_zone, - int migratetype, unsigned long *did_some_progress, - bool sync_migration) + int migratetype, bool sync_migration, + bool *deferred_compaction, + unsigned long *did_some_progress) { return NULL; } @@ -2179,6 +2192,7 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, unsigned long pages_reclaimed = 0; unsigned long did_some_progress; bool sync_migration = false; + bool deferred_compaction = false; /* * In the slowpath, we sanity check order to avoid ever trying to @@ -2259,12 +2273,22 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, zonelist, high_zoneidx, nodemask, alloc_flags, preferred_zone, - migratetype, &did_some_progress, - sync_migration); + migratetype, sync_migration, + &deferred_compaction, + &did_some_progress); if (page) goto got_pg; sync_migration = true; + /* + * If compaction is deferred for high-order allocations, it is because + * sync compaction recently failed. In this is the case and the caller + * has requested the system not be heavily disrupted, fail the + * allocation now instead of entering direct reclaim + */ + if (deferred_compaction && (gfp_mask & __GFP_NO_KSWAPD)) + goto nopage; + /* Try direct reclaim and then allocating */ page = __alloc_pages_direct_reclaim(gfp_mask, order, zonelist, high_zoneidx, @@ -2328,8 +2352,9 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, zonelist, high_zoneidx, nodemask, alloc_flags, preferred_zone, - migratetype, &did_some_progress, - sync_migration); + migratetype, sync_migration, + &deferred_compaction, + &did_some_progress); if (page) goto got_pg; } -- GitLab