summaryrefslogtreecommitdiffstats
path: root/mm/vmscan.c
diff options
context:
space:
mode:
authorHuang Ying <ying.huang@intel.com>2017-07-06 15:37:31 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2017-07-06 16:24:31 -0700
commit747552b1e71b400fa32a221e072be2c0b7661f14 (patch)
tree5f2e457a2b500159af4f7d98e62501ecd299c547 /mm/vmscan.c
parentb8f593cd0896b8b14c2b494a9776531b5cd54d98 (diff)
downloadlinux-747552b1e71b400fa32a221e072be2c0b7661f14.tar.bz2
mm, THP, swap: enable THP swap optimization only if has compound map
If there is no compound map for a THP (Transparent Huge Page), it is possible that the map count of some sub-pages of the THP is 0. So it is better to split the THP before swapping out. In this way, the sub-pages not mapped will be freed, and we can avoid the unnecessary swap out operations for these sub-pages. Link: http://lkml.kernel.org/r/20170515112522.32457-6-ying.huang@intel.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Ebru Akagunduz <ebru.akagunduz@gmail.com> Cc: Hugh Dickins <hughd@google.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@redhat.com> Cc: Shaohua Li <shli@kernel.org> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/vmscan.c')
-rw-r--r--mm/vmscan.c17
1 files changed, 13 insertions, 4 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c
index abaf0215a352..aebb157258f2 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1125,10 +1125,19 @@ static unsigned long shrink_page_list(struct list_head *page_list,
!PageSwapCache(page)) {
if (!(sc->gfp_mask & __GFP_IO))
goto keep_locked;
- /* cannot split THP, skip it */
- if (PageTransHuge(page) &&
- !can_split_huge_page(page, NULL))
- goto activate_locked;
+ if (PageTransHuge(page)) {
+ /* cannot split THP, skip it */
+ if (!can_split_huge_page(page, NULL))
+ goto activate_locked;
+ /*
+ * Split pages without a PMD map right
+ * away. Chances are some or all of the
+ * tail pages can be freed without IO.
+ */
+ if (!compound_mapcount(page) &&
+ split_huge_page_to_list(page, page_list))
+ goto activate_locked;
+ }
if (!add_to_swap(page)) {
if (!PageTransHuge(page))
goto activate_locked;