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From: Mel Gorman <mgorman@techsingularity.net>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: David Rientjes <rientjes@google.com>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Vlastimil Babka <vbabka@suse.cz>,
	Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
	Linux-MM <linux-mm@kvack.org>,
	Mel Gorman <mgorman@techsingularity.net>
Subject: [PATCH 14/22] mm, compaction: Check early for huge pages encountered by the migration scanner
Date: Fri, 18 Jan 2019 17:51:28 +0000	[thread overview]
Message-ID: <20190118175136.31341-15-mgorman@techsingularity.net> (raw)
In-Reply-To: <20190118175136.31341-1-mgorman@techsingularity.net>

When scanning for sources or targets, PageCompound is checked for huge
pages as they can be skipped quickly but it happens relatively late after
a lot of setup and checking. This patch short-cuts the check to make it
earlier. It might still change when the lock is acquired but this has
less overhead overall. The free scanner advances but the migration scanner
does not. Typically the free scanner encounters more movable blocks that
change state over the lifetime of the system and also tends to scan more
aggressively as it's actively filling its portion of the physical address
space with data. This could change in the future but for the moment,
this worked better in practice and incurred fewer scan restarts.

The impact on latency and allocation success rates is marginal but the
free scan rates are reduced by 15% and system CPU usage is reduced by
3.3%. The 2-socket results are not materially different.

Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
---
 mm/compaction.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/mm/compaction.c b/mm/compaction.c
index b261c0bfac24..14bb66d48392 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -1061,6 +1061,9 @@ static bool suitable_migration_source(struct compact_control *cc,
 {
 	int block_mt;
 
+	if (pageblock_skip_persistent(page))
+		return false;
+
 	if ((cc->mode != MIGRATE_ASYNC) || !cc->direct_compaction)
 		return true;
 
@@ -1695,12 +1698,17 @@ static isolate_migrate_t isolate_migratepages(struct zone *zone,
 			continue;
 
 		/*
-		 * For async compaction, also only scan in MOVABLE blocks.
-		 * Async compaction is optimistic to see if the minimum amount
-		 * of work satisfies the allocation.
+		 * For async compaction, also only scan in MOVABLE blocks
+		 * without huge pages. Async compaction is optimistic to see
+		 * if the minimum amount of work satisfies the allocation.
+		 * The cached PFN is updated as it's possible that all
+		 * remaining blocks between source and target are unsuitable
+		 * and the compaction scanners fail to meet.
 		 */
-		if (!suitable_migration_source(cc, page))
+		if (!suitable_migration_source(cc, page)) {
+			update_cached_migrate(cc, block_end_pfn);
 			continue;
+		}
 
 		/* Perform the isolation */
 		low_pfn = isolate_migratepages_block(cc, low_pfn,
-- 
2.16.4


  parent reply	other threads:[~2019-01-18 17:54 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-18 17:51 [PATCH 00/22] Increase success rates and reduce latency of compaction v3 Mel Gorman
2019-01-18 17:51 ` [PATCH 01/22] mm, compaction: Shrink compact_control Mel Gorman
2019-01-18 17:51 ` [PATCH 02/22] mm, compaction: Rearrange compact_control Mel Gorman
2019-01-18 17:51 ` [PATCH 03/22] mm, compaction: Remove last_migrated_pfn from compact_control Mel Gorman
2019-01-18 17:51 ` [PATCH 04/22] mm, compaction: Remove unnecessary zone parameter in some instances Mel Gorman
2019-01-18 17:51 ` [PATCH 05/22] mm, compaction: Rename map_pages to split_map_pages Mel Gorman
2019-01-18 17:51 ` [PATCH 06/22] mm, migrate: Immediately fail migration of a page with no migration handler Mel Gorman
2019-01-18 17:51 ` [PATCH 07/22] mm, compaction: Always finish scanning of a full pageblock Mel Gorman
2019-01-18 17:51 ` [PATCH 08/22] mm, compaction: Ignore the fragmentation avoidance boost for isolation and compaction Mel Gorman
2019-01-18 17:51 ` [PATCH 09/22] mm, compaction: Use free lists to quickly locate a migration source Mel Gorman
2019-01-31 13:55   ` Vlastimil Babka
2019-01-31 14:12     ` Vlastimil Babka
2019-02-01 15:06     ` Mel Gorman
2019-02-04  8:55       ` [PATCH] mm, compaction: Use free lists to quickly locate a migration source -fix Mel Gorman
2019-02-08 17:10   ` [PATCH 09/22] mm, compaction: Use free lists to quickly locate a migration source Vlastimil Babka
2019-01-18 17:51 ` [PATCH 10/22] mm, compaction: Keep migration source private to a single compaction instance Mel Gorman
2019-01-18 17:51 ` [PATCH 11/22] mm, compaction: Use free lists to quickly locate a migration target Mel Gorman
2019-01-31 14:52   ` Vlastimil Babka
2019-02-01 14:51     ` Mel Gorman
2019-02-01 14:58       ` Vlastimil Babka
2019-02-04 12:01         ` [PATCH] mm, compaction: Use free lists to quickly locate a migration source -fix Mel Gorman
2021-01-12  5:19     ` [PATCH] mm, compaction: make sure we isolate a valid freepage when high_pfn is used Rokudo Yan
2021-01-12  9:10       ` Mel Gorman
2021-01-12  9:47         ` [PATCH] mm, compaction: move high_pfn to the for loop scope Rokudo Yan
2021-01-12 10:45           ` Mel Gorman
2021-01-12 10:48           ` Vlastimil Babka
2021-01-12 22:27           ` Andrew Morton
2021-01-18  7:41             ` Rokudo Yan
2021-01-18  9:42               ` Mel Gorman
2019-01-18 17:51 ` [PATCH 12/22] mm, compaction: Avoid rescanning the same pageblock multiple times Mel Gorman
2019-01-18 17:51 ` [PATCH 13/22] mm, compaction: Finish pageblock scanning on contention Mel Gorman
2019-01-18 17:51 ` Mel Gorman [this message]
2019-01-18 17:51 ` [PATCH 15/22] mm, compaction: Keep cached migration PFNs synced for unusable pageblocks Mel Gorman
2019-01-18 17:51 ` [PATCH 16/22] mm, compaction: Rework compact_should_abort as compact_check_resched Mel Gorman
2019-01-18 17:51 ` [PATCH 17/22] mm, compaction: Do not consider a need to reschedule as contention Mel Gorman
2019-01-18 17:51 ` [PATCH 18/22] mm, compaction: Reduce premature advancement of the migration target scanner Mel Gorman
2019-01-18 17:51 ` [PATCH 19/22] mm, compaction: Round-robin the order while searching the free lists for a target Mel Gorman
2019-01-18 17:51 ` [PATCH 20/22] mm, compaction: Sample pageblocks for free pages Mel Gorman
2019-01-31 15:39   ` Vlastimil Babka
2019-01-18 17:51 ` [PATCH 21/22] mm, compaction: Be selective about what pageblocks to clear skip hints Mel Gorman
2019-01-31 15:45   ` Vlastimil Babka
2019-01-18 17:51 ` [PATCH 22/22] mm, compaction: Capture a page under direct compaction Mel Gorman
2019-01-31 16:11   ` Vlastimil Babka
2019-02-01 14:38     ` [PATCH] mm, compaction: Capture a page under direct compaction -fix Mel Gorman
2019-01-24  8:53 ` [PATCH 00/22] Increase success rates and reduce latency of compaction v3 Mel Gorman

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