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authorMinchan Kim <minchan@kernel.org>2017-11-15 17:33:04 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2017-11-15 18:21:02 -0800
commit539a6fea7fdcade532bd3e77be2862a683f8f0c9 (patch)
treef3255c208ee4803cea857226b880a9838eccd2c8 /include
parent23c47d2ada9f96731492a67b28c0072715075baa (diff)
downloadlinux-539a6fea7fdcade532bd3e77be2862a683f8f0c9.tar.gz
mm, swap: introduce SWP_SYNCHRONOUS_IO
If rw-page based fast storage is used for swap devices, we need to
detect it to enhance swap IO operations.  This patch is preparation for
optimizing of swap-in operation with next patch.

Link: http://lkml.kernel.org/r/1505886205-9671-4-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Ilya Dryomov <idryomov@gmail.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
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.h3
1 files changed, 2 insertions, 1 deletions
diff --git a/include/linux/swap.h b/include/linux/swap.h
index f02fb5db8914..933d7c0c3542 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -171,8 +171,9 @@ enum {
 	SWP_AREA_DISCARD = (1 << 8),	/* single-time swap area discards */
 	SWP_PAGE_DISCARD = (1 << 9),	/* freed swap page-cluster discards */
 	SWP_STABLE_WRITES = (1 << 10),	/* no overwrite PG_writeback pages */
+	SWP_SYNCHRONOUS_IO = (1 << 11),	/* synchronous IO is efficient */
 					/* add others here before... */
-	SWP_SCANNING	= (1 << 11),	/* refcount in scan_swap_map */
+	SWP_SCANNING	= (1 << 12),	/* refcount in scan_swap_map */
 };
 
 #define SWAP_CLUSTER_MAX 32UL