mm, compaction: keep cached migration PFNs synced for unusable pageblocks
authorMel Gorman <mgorman@techsingularity.net>
Tue, 5 Mar 2019 23:45:18 +0000 (15:45 -0800)
committerLinus Torvalds <torvalds@linux-foundation.org>
Wed, 6 Mar 2019 05:07:17 +0000 (21:07 -0800)
commit8854c55f54bcc104e3adae42abe16948286ec75c
tree0a7ea9d9c74534019d11145c8b5b303823882221
parent9bebefd59084af7c75b66eeee241bf0777f39b88
mm, compaction: keep cached migration PFNs synced for unusable pageblocks

Migrate has separate cached PFNs for ASYNC and SYNC* migration on the
basis that some migrations will fail in ASYNC mode.  However, if the
cached PFNs match at the start of scanning and pageblocks are skipped
due to having no isolation candidates, then the sync state does not
matter.  This patch keeps matching cached PFNs in sync until a pageblock
with isolation candidates is found.

The actual benefit is marginal given that the sync scanner following the
async scanner will often skip a number of pageblocks but it's useless
work.  Any benefit depends heavily on whether the scanners restarted
recently.

Link: http://lkml.kernel.org/r/20190118175136.31341-16-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>
mm/compaction.c