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| author | Minchan Kim <minchan@kernel.org> | 2017-11-15 17:33:07 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-11-15 18:21:02 -0800 |
| commit | 0bcac06f27d7528591c27ac2b093ccd71c5d0168 (patch) | |
| tree | b8261d05b232e57a58a7fe90306cad5d545de900 /include/linux/swap.h | |
| parent | 539a6fea7fdcade532bd3e77be2862a683f8f0c9 (diff) | |
| download | lwn-0bcac06f27d7528591c27ac2b093ccd71c5d0168.tar.gz lwn-0bcac06f27d7528591c27ac2b093ccd71c5d0168.zip | |
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 'include/linux/swap.h')
| -rw-r--r-- | include/linux/swap.h | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/include/linux/swap.h b/include/linux/swap.h index 933d7c0c3542..32c06f028c7b 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -466,6 +466,7 @@ extern int page_swapcount(struct page *); 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 *); +extern struct swap_info_struct *swp_swap_info(swp_entry_t entry); extern bool reuse_swap_page(struct page *, int *); extern int try_to_free_swap(struct page *); struct backing_dev_info; @@ -474,6 +475,16 @@ extern void exit_swap_address_space(unsigned int type); #else /* CONFIG_SWAP */ +static inline int swap_readpage(struct page *page, bool do_poll) +{ + return 0; +} + +static inline struct swap_info_struct *swp_swap_info(swp_entry_t entry) +{ + return NULL; +} + #define swap_address_space(entry) (NULL) #define get_nr_swap_pages() 0L #define total_swap_pages 0L |