diff options
| author | Minchan Kim <minchan@kernel.org> | 2017-11-15 17:33:11 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-11-15 18:21:02 -0800 |
| commit | aa8d22a11da933dbf880b4933b58931f4aefe91c (patch) | |
| tree | ed7a7c1ecdfa4da6079858dfc0cfb6fbb65e3286 /mm/swapfile.c | |
| parent | 0bcac06f27d7528591c27ac2b093ccd71c5d0168 (diff) | |
mm: swap: SWP_SYNCHRONOUS_IO: skip swapcache only if swapped page has no other reference
When SWP_SYNCHRONOUS_IO swapped-in pages are shared by several
processes, it can cause unnecessary memory wastage by skipping swap
cache. Because, with swapin fault by read, they could share a page if
the page were in swap cache. Thus, it avoids allocating same content
new pages.
This patch makes the swapcache skipping work only if the swap pte is
non-sharable.
[akpm@linux-foundation.org: coding-style fixes]
Link: http://lkml.kernel.org/r/1507620825-5537-1-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Ilya Dryomov <idryomov@gmail.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Huang Ying <ying.huang@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/swapfile.c')
| -rw-r--r-- | mm/swapfile.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/mm/swapfile.c b/mm/swapfile.c index 85aff8a42801..3074b02eaa09 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -1328,6 +1328,13 @@ int page_swapcount(struct page *page) return count; } +int __swap_count(struct swap_info_struct *si, swp_entry_t entry) +{ + pgoff_t offset = swp_offset(entry); + + return swap_count(si->swap_map[offset]); +} + static int swap_swapcount(struct swap_info_struct *si, swp_entry_t entry) { int count = 0; |