From c8f7de0bfae36e8532e5e25a39d15407f02aca78 Mon Sep 17 00:00:00 2001 From: Michal Hocko Date: Fri, 20 May 2016 16:56:47 -0700 Subject: [PATCH] mm, compaction: distinguish between full and partial COMPACT_COMPLETE COMPACT_COMPLETE now means that compaction and free scanner met. This is not very useful information if somebody just wants to use this feedback and make any decisions based on that. The current caller might be a poor guy who just happened to scan tiny portion of the zone and that could be the reason no suitable pages were compacted. Make sure we distinguish the full and partial zone walks. Consumers should treat COMPACT_PARTIAL_SKIPPED as a potential success and be optimistic in retrying. The existing users of COMPACT_COMPLETE are conservatively changed to use COMPACT_PARTIAL_SKIPPED as well but some of them should be probably reconsidered and only defer the compaction only for COMPACT_COMPLETE with the new semantic. This patch shouldn't introduce any functional changes. Signed-off-by: Michal Hocko Acked-by: Vlastimil Babka Acked-by: Hillf Danton Cc: David Rientjes Cc: Johannes Weiner Cc: Joonsoo Kim Cc: Mel Gorman Cc: Tetsuo Handa Cc: Vladimir Davydov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/compaction.h | 10 +++++++++- include/trace/events/compaction.h | 1 + mm/compaction.c | 14 +++++++++++--- mm/internal.h | 1 + 4 files changed, 22 insertions(+), 4 deletions(-) diff --git a/include/linux/compaction.h b/include/linux/compaction.h index 11f228712ed5..9b37f9d3f7a8 100644 --- a/include/linux/compaction.h +++ b/include/linux/compaction.h @@ -21,7 +21,15 @@ enum compact_result { * pages */ COMPACT_PARTIAL, - /* The full zone was compacted */ + /* + * direct compaction has scanned part of the zone but wasn't successfull + * to compact suitable pages. + */ + COMPACT_PARTIAL_SKIPPED, + /* + * The full zone was compacted scanned but wasn't successfull to compact + * suitable pages. + */ COMPACT_COMPLETE, /* For more detailed tracepoint output */ COMPACT_NO_SUITABLE_PAGE, diff --git a/include/trace/events/compaction.h b/include/trace/events/compaction.h index 6ba16c86d7db..36e2d6fb1360 100644 --- a/include/trace/events/compaction.h +++ b/include/trace/events/compaction.h @@ -14,6 +14,7 @@ EM( COMPACT_DEFERRED, "deferred") \ EM( COMPACT_CONTINUE, "continue") \ EM( COMPACT_PARTIAL, "partial") \ + EM( COMPACT_PARTIAL_SKIPPED, "partial_skipped") \ EM( COMPACT_COMPLETE, "complete") \ EM( COMPACT_NO_SUITABLE_PAGE, "no_suitable_page") \ EM( COMPACT_NOT_SUITABLE_ZONE, "not_suitable_zone") \ diff --git a/mm/compaction.c b/mm/compaction.c index b2b94474dd28..4af1577adb5c 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -1252,7 +1252,10 @@ static enum compact_result __compact_finished(struct zone *zone, struct compact_ if (cc->direct_compaction) zone->compact_blockskip_flush = true; - return COMPACT_COMPLETE; + if (cc->whole_zone) + return COMPACT_COMPLETE; + else + return COMPACT_PARTIAL_SKIPPED; } if (is_via_compact_memory(cc->order)) @@ -1413,6 +1416,10 @@ static enum compact_result compact_zone(struct zone *zone, struct compact_contro zone->compact_cached_migrate_pfn[0] = cc->migrate_pfn; zone->compact_cached_migrate_pfn[1] = cc->migrate_pfn; } + + if (cc->migrate_pfn == start_pfn) + cc->whole_zone = true; + cc->last_migrated_pfn = 0; trace_mm_compaction_begin(start_pfn, cc->migrate_pfn, @@ -1634,7 +1641,8 @@ enum compact_result try_to_compact_pages(gfp_t gfp_mask, unsigned int order, goto break_loop; } - if (mode != MIGRATE_ASYNC && status == COMPACT_COMPLETE) { + if (mode != MIGRATE_ASYNC && (status == COMPACT_COMPLETE || + status == COMPACT_PARTIAL_SKIPPED)) { /* * We think that allocation won't succeed in this zone * so we defer compaction there. If it ends up @@ -1881,7 +1889,7 @@ static void kcompactd_do_work(pg_data_t *pgdat) cc.classzone_idx, 0)) { success = true; compaction_defer_reset(zone, cc.order, false); - } else if (status == COMPACT_COMPLETE) { + } else if (status == COMPACT_PARTIAL_SKIPPED || status == COMPACT_COMPLETE) { /* * We use sync migration mode here, so we defer like * sync direct compaction does. diff --git a/mm/internal.h b/mm/internal.h index 3ac544f1963f..f6f3353b0868 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -174,6 +174,7 @@ struct compact_control { enum migrate_mode mode; /* Async or sync migration mode */ bool ignore_skip_hint; /* Scan blocks even if marked skip */ bool direct_compaction; /* False from kcompactd or /proc/... */ + bool whole_zone; /* Whole zone has been scanned */ int order; /* order a direct compactor needs */ const gfp_t gfp_mask; /* gfp mask of a direct compactor */ const unsigned int alloc_flags; /* alloc flags of a direct compactor */