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authorMinchan Kim <minchan@kernel.org>2017-11-15 17:33:11 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2017-11-15 18:21:02 -0800
commitaa8d22a11da933dbf880b4933b58931f4aefe91c (patch)
treeed7a7c1ecdfa4da6079858dfc0cfb6fbb65e3286 /include
parent0bcac06f27d7528591c27ac2b093ccd71c5d0168 (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 'include')
-rw-r--r--include/linux/swap.h6
1 files changed, 6 insertions, 0 deletions
diff --git a/include/linux/swap.h b/include/linux/swap.h
index 32c06f028c7b..8b8a6f965785 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -463,6 +463,7 @@ extern unsigned int count_swap_pages(int, int);
extern sector_t map_swap_page(struct page *, struct block_device **);
extern sector_t swapdev_block(int, pgoff_t);
extern int page_swapcount(struct page *);
+extern int __swap_count(struct swap_info_struct *si, swp_entry_t entry);
extern int __swp_swapcount(swp_entry_t entry);
extern int swp_swapcount(swp_entry_t entry);
extern struct swap_info_struct *page_swap_info(struct page *);
@@ -589,6 +590,11 @@ static inline int page_swapcount(struct page *page)
return 0;
}
+static inline int __swap_count(struct swap_info_struct *si, swp_entry_t entry)
+{
+ return 0;
+}
+
static inline int __swp_swapcount(swp_entry_t entry)
{
return 0;