diff options
| author | Mel Gorman <mgorman@techsingularity.net> | 2019-02-05 13:04:30 +1100 |
|---|---|---|
| committer | Stephen Rothwell <sfr@canb.auug.org.au> | 2019-02-05 13:04:30 +1100 |
| commit | f1d01bdeee3f8513e3e4e3d8ba57724c2f71c78d (patch) | |
| tree | d3362a505ed99628b6b7f9021b763ebe066d1936 | |
| parent | 85397c4ec77c76fdc7471e1f4b4b8c5b3c212813 (diff) | |
| download | linux-next-f1d01bdeee3f8513e3e4e3d8ba57724c2f71c78d.tar.gz | |
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: Stephen Rothwell <sfr@canb.auug.org.au>
| -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 9623614ffb1d..d278127c9c15 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -917,7 +917,7 @@ 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); } |