From 539a6fea7fdcade532bd3e77be2862a683f8f0c9 Mon Sep 17 00:00:00 2001 From: Minchan Kim Date: Wed, 15 Nov 2017 17:33:04 -0800 Subject: [PATCH] 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 Cc: Hugh Dickins Cc: Christoph Hellwig Cc: Dan Williams Cc: Ilya Dryomov Cc: Jens Axboe Cc: Ross Zwisler Cc: Sergey Senozhatsky Cc: Huang Ying Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/swap.h | 3 ++- mm/swapfile.c | 3 +++ 2 files changed, 5 insertions(+), 1 deletion(-) 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 diff --git a/mm/swapfile.c b/mm/swapfile.c index e47a21e64764..cb08fa65819f 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -3169,6 +3169,9 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) if (bdi_cap_stable_pages_required(inode_to_bdi(inode))) p->flags |= SWP_STABLE_WRITES; + if (bdi_cap_synchronous_io(inode_to_bdi(inode))) + p->flags |= SWP_SYNCHRONOUS_IO; + if (p->bdev && blk_queue_nonrot(bdev_get_queue(p->bdev))) { int cpu; unsigned long ci, nr_cluster;