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| author | Mel Gorman <mgorman@techsingularity.net> | 2019-03-05 15:44:43 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2019-03-05 21:07:16 -0800 |
| commit | 806031bb5ec36ed879d64249d5a5cf9c6657f89d (patch) | |
| tree | 25a9bc8e338915b0f755701575ee0ec95cf1c110 /mm/migrate.c | |
| parent | 4469ab98477b290f6728b79f8d225d9d88ce16e3 (diff) | |
| download | lwn-806031bb5ec36ed879d64249d5a5cf9c6657f89d.tar.gz lwn-806031bb5ec36ed879d64249d5a5cf9c6657f89d.zip | |
mm, migrate: immediately fail migration of a page with no migration handler
Pages with no migration handler use a fallback handler which sometimes
works and sometimes persistently retries. A historical example was
blockdev pages but there are others such as odd refcounting when
page->private is used. These are retried multiple times which is
wasteful during compaction so this patch will fail migration faster
unless the caller specifies MIGRATE_SYNC.
This is not expected to help THP allocation success rates but it did
reduce latencies very slightly in some cases.
1-socket thpfioscale
4.20.0 4.20.0
noreserved-v2r15 failfast-v2r15
Amean fault-both-1 0.00 ( 0.00%) 0.00 * 0.00%*
Amean fault-both-3 3839.67 ( 0.00%) 3833.72 ( 0.15%)
Amean fault-both-5 5177.47 ( 0.00%) 4967.15 ( 4.06%)
Amean fault-both-7 7245.03 ( 0.00%) 7139.19 ( 1.46%)
Amean fault-both-12 11534.89 ( 0.00%) 11326.30 ( 1.81%)
Amean fault-both-18 16241.10 ( 0.00%) 16270.70 ( -0.18%)
Amean fault-both-24 19075.91 ( 0.00%) 19839.65 ( -4.00%)
Amean fault-both-30 22712.11 ( 0.00%) 21707.05 ( 4.43%)
Amean fault-both-32 21692.92 ( 0.00%) 21968.16 ( -1.27%)
The 2-socket results are not materially different. Scan rates are
similar as expected.
Link: http://lkml.kernel.org/r/20190118175136.31341-7-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: David Rientjes <rientjes@google.com>
Cc: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/migrate.c')
| -rw-r--r-- | mm/migrate.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/migrate.c b/mm/migrate.c index 0413596fc523..0e9888cb33ad 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -911,7 +911,7 @@ 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); } |