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authorMinchan Kim <minchan@kernel.org>2017-11-16 04:33:07 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2017-11-16 05:21:02 +0300
commit0bcac06f27d7528591c27ac2b093ccd71c5d0168 (patch)
treeb8261d05b232e57a58a7fe90306cad5d545de900 /mm/swapfile.c
parent539a6fea7fdcade532bd3e77be2862a683f8f0c9 (diff)
downloadlinux-0bcac06f27d7528591c27ac2b093ccd71c5d0168.tar.xz
mm, swap: skip swapcache for swapin of synchronous device
With fast swap storage, the platforms want to use swap more aggressively and swap-in is crucial to application latency. The rw_page() based synchronous devices like zram, pmem and btt are such fast storage. When I profile swapin performance with zram lz4 decompress test, S/W overhead is more than 70%. Maybe, it would be bigger in nvdimm. This patch aims to reduce swap-in latency by skipping swapcache if the swap device is synchronous device like rw_page based device. It enhances 45% my swapin test(5G sequential swapin, no readahead, from 2.41sec to 1.64sec). Link: http://lkml.kernel.org/r/1505886205-9671-5-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.c11
1 files changed, 7 insertions, 4 deletions
diff --git a/mm/swapfile.c b/mm/swapfile.c
index cb08fa65819f..85aff8a42801 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -3455,10 +3455,15 @@ int swapcache_prepare(swp_entry_t entry)
return __swap_duplicate(entry, SWAP_HAS_CACHE);
}
+struct swap_info_struct *swp_swap_info(swp_entry_t entry)
+{
+ return swap_info[swp_type(entry)];
+}
+
struct swap_info_struct *page_swap_info(struct page *page)
{
- swp_entry_t swap = { .val = page_private(page) };
- return swap_info[swp_type(swap)];
+ swp_entry_t entry = { .val = page_private(page) };
+ return swp_swap_info(entry);
}
/*
@@ -3466,7 +3471,6 @@ struct swap_info_struct *page_swap_info(struct page *page)
*/
struct address_space *__page_file_mapping(struct page *page)
{
- VM_BUG_ON_PAGE(!PageSwapCache(page), page);
return page_swap_info(page)->swap_file->f_mapping;
}
EXPORT_SYMBOL_GPL(__page_file_mapping);
@@ -3474,7 +3478,6 @@ EXPORT_SYMBOL_GPL(__page_file_mapping);
pgoff_t __page_file_index(struct page *page)
{
swp_entry_t swap = { .val = page_private(page) };
- VM_BUG_ON_PAGE(!PageSwapCache(page), page);
return swp_offset(swap);
}
EXPORT_SYMBOL_GPL(__page_file_index);