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From: Mel Gorman <mgorman@techsingularity.net>
To: Linux-MM <linux-mm@kvack.org>
Cc: David Rientjes <rientjes@google.com>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Michal Hocko <mhocko@kernel.org>,
	ying.huang@intel.com, kirill@shutemov.name,
	Andrew Morton <akpm@linux-foundation.org>,
	Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
	Mel Gorman <mgorman@techsingularity.net>
Subject: [PATCH 06/14] mm, migrate: Immediately fail migration of a page with no migration handler
Date: Fri, 14 Dec 2018 23:03:02 +0000	[thread overview]
Message-ID: <20181214230310.572-7-mgorman@techsingularity.net> (raw)
In-Reply-To: <20181214230310.572-1-mgorman@techsingularity.net>

Pages with no migration handler use a fallback hander which sometimes
works and sometimes persistently fails such as blockdev pages. Migration
will retry a number of times on these persistent pages which is wasteful
during compaction. This patch will fail migration immediately unless the
caller is in MIGRATE_SYNC mode which indicates the caller is willing to
wait while being persistent.

This is not expected to help THP allocation success rates but it does
reduce latencies slightly.

1-socket thpfioscale
                                    4.20.0-rc6             4.20.0-rc6
                               noreserved-v1r4          failfast-v1r4
Amean     fault-both-1         0.00 (   0.00%)        0.00 *   0.00%*
Amean     fault-both-3      2276.15 (   0.00%)     3867.54 * -69.92%*
Amean     fault-both-5      4992.20 (   0.00%)     5313.20 (  -6.43%)
Amean     fault-both-7      7373.30 (   0.00%)     7039.11 (   4.53%)
Amean     fault-both-12    11911.52 (   0.00%)    11328.29 (   4.90%)
Amean     fault-both-18    17209.42 (   0.00%)    16455.34 (   4.38%)
Amean     fault-both-24    20943.71 (   0.00%)    20448.94 (   2.36%)
Amean     fault-both-30    22703.00 (   0.00%)    21655.07 (   4.62%)
Amean     fault-both-32    22461.41 (   0.00%)    21415.35 (   4.66%)

The 2-socket results are not materially different. Scan rates are
similar as expected.

Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
---
 mm/migrate.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/migrate.c b/mm/migrate.c
index df17a710e2c7..0e27a10429e2 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -885,7 +885,7 @@ static int fallback_migrate_page(struct address_space *mapping,
 	 */
 	if (page_has_private(page) &&
 	    !try_to_release_page(page, GFP_KERNEL))
-		return -EAGAIN;
+		return mode == MIGRATE_SYNC ? -EAGAIN : -EBUSY;
 
 	return migrate_page(mapping, newpage, page, mode);
 }
-- 
2.16.4

  parent reply	other threads:[~2018-12-14 23:03 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-12-14 23:02 [RFC PATCH 00/14] Increase success rates and reduce latency of compaction v1 Mel Gorman
2018-12-14 23:02 ` [PATCH 01/14] mm, compaction: Shrink compact_control Mel Gorman
2018-12-17 12:27   ` Vlastimil Babka
2018-12-14 23:02 ` [PATCH 02/14] mm, compaction: Rearrange compact_control Mel Gorman
2018-12-17 13:20   ` Vlastimil Babka
2018-12-14 23:02 ` [PATCH 03/14] mm, compaction: Remove last_migrated_pfn from compact_control Mel Gorman
2018-12-17 13:50   ` Vlastimil Babka
2018-12-14 23:03 ` [PATCH 04/14] mm, compaction: Rename map_pages to split_map_pages Mel Gorman
2018-12-17 14:06   ` Vlastimil Babka
2018-12-17 14:30     ` Mel Gorman
2018-12-14 23:03 ` [PATCH 05/14] mm, compaction: Skip pageblocks with reserved pages Mel Gorman
2018-12-18  8:08   ` Vlastimil Babka
2018-12-18  8:38     ` Mel Gorman
2018-12-14 23:03 ` Mel Gorman [this message]
2018-12-18  9:06   ` [PATCH 06/14] mm, migrate: Immediately fail migration of a page with no migration handler Vlastimil Babka
2018-12-18  9:55     ` Mel Gorman
2018-12-20 19:44   ` Yang Shi
2018-12-20 19:44     ` Yang Shi
2018-12-20 20:31     ` Mel Gorman
2018-12-14 23:03 ` [PATCH 07/14] mm, compaction: Always finish scanning of a full pageblock Mel Gorman
2018-12-18  9:23   ` Vlastimil Babka
2018-12-14 23:03 ` [PATCH 08/14] mm, compaction: Use the page allocator bulk-free helper for lists of pages Mel Gorman
2018-12-18  9:55   ` Vlastimil Babka
2018-12-19 16:04     ` Mel Gorman
2018-12-14 23:03 ` [PATCH 09/14] mm, compaction: Ignore the fragmentation avoidance boost for isolation and compaction Mel Gorman
2018-12-18 12:36   ` Vlastimil Babka
2018-12-18 13:51     ` Mel Gorman
2018-12-18 13:58       ` Vlastimil Babka
2018-12-18 14:29         ` Mel Gorman
2018-12-14 23:04 ` [PATCH 10/14] mm, compaction: Use free lists to quickly locate a migration source Mel Gorman
2018-12-14 23:05 ` [PATCH 11/14] mm, compaction: Keep migration source private to a single compaction instance Mel Gorman
2018-12-14 23:05 ` [PATCH 12/14] mm, compaction: Use free lists to quickly locate a migration target Mel Gorman
2018-12-14 23:05 ` [PATCH 13/14] mm, compaction: Capture a page under direct compaction Mel Gorman
2018-12-14 23:06 ` [PATCH 14/14] mm, compaction: Do not direct compact remote memory Mel Gorman

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