mm/compaction: do not call suitable_migration_target() on every page
mm/compaction: do not call suitable_migration_target() on every page

suitable_migration_target() checks that pageblock is suitable for
migration target.  In isolate_freepages_block(), it is called on every
page and this is inefficient.  So make it called once per pageblock.

suitable_migration_target() also checks if page is highorder or not, but
it's criteria for highorder is pageblock order.  So calling it once
within pageblock range has no problem.

Signed-off-by: Joonsoo Kim <bb6c8cfe7699e0f11d1bee88022eb563a5f8e881@lge.com>
Acked-by: Vlastimil Babka <db766431e3f0373ca1ec8fa855cfd5f84b2f2eb6@suse.cz>
Cc: Mel Gorman <39ea6a09710987173e32e37c86918024a0f441c1@suse.de>
Cc: Rik van Riel <a21938f5d463ddf41aa718934c205ca2cce8ebbc@redhat.com>
Signed-off-by: Andrew Morton <5c1e68b099950c134891f0b6e179498a8ebe9cf9@linux-foundation.org>
Signed-off-by: Linus Torvalds <69652caca27c8b940640ad396ab71f93cacec34f@linux-foundation.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs