mm: munlock: remove redundant get_page/put_page pair on the fast path
authorVlastimil Babka <vbabka@suse.cz>
Wed, 11 Sep 2013 21:22:33 +0000 (14:22 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Wed, 11 Sep 2013 22:58:00 +0000 (15:58 -0700)
commit5b40998ae35cf64561868370e6c9f3d3e94b6bf7
tree24f7142d850df3512392004501fc9db7573fc031
parent56afe477df3cbbcd656682d0355ef7d9eb8bdd81
mm: munlock: remove redundant get_page/put_page pair on the fast path

The performance of the fast path in munlock_vma_range() can be further
improved by avoiding atomic ops of a redundant get_page()/put_page() pair.

When calling get_page() during page isolation, we already have the pin
from follow_page_mask().  This pin will be then returned by
__pagevec_lru_add(), after which we do not reference the pages anymore.

After this patch, an 8% speedup was measured for munlocking a 56GB large
memory area with THP disabled.

Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Jörn Engel <joern@logfs.org>
Acked-by: Mel Gorman <mgorman@suse.de>
Cc: Michel Lespinasse <walken@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/mlock.c