diff options
| author | Huang Ying <ying.huang@intel.com> | 2017-07-07 00:37:31 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-07-07 01:24:31 +0200 |
| commit | 747552b1e71b400fa32a221e072be2c0b7661f14 (patch) | |
| tree | 5f2e457a2b500159af4f7d98e62501ecd299c547 /mm | |
| parent | mm, THP, swap: check whether THP can be split firstly (diff) | |
| download | linux-747552b1e71b400fa32a221e072be2c0b7661f14.tar.xz linux-747552b1e71b400fa32a221e072be2c0b7661f14.zip | |
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')
| -rw-r--r-- | mm/vmscan.c | 17 |
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; |