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From: Minchan Kim <minchan@kernel.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	kernel-team <kernel-team@lge.com>, Christoph Hellwig <hch@lst.de>,
	Minchan Kim <minchan@kernel.org>, Hugh Dickins <hughd@google.com>
Subject: [PATCH v2 3/4] mm:swap: introduce SWP_SYNCHRONOUS_IO
Date: Wed, 20 Sep 2017 14:43:24 +0900
Message-ID: <1505886205-9671-4-git-send-email-minchan@kernel.org> (raw)
In-Reply-To: <1505886205-9671-1-git-send-email-minchan@kernel.org>

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.

Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Minchan Kim <minchan@kernel.org>
---
 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 8a807292037f..fbb33919d1c6 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -170,8 +170,9 @@ 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 bf91dc9e7a79..1305591cde4d 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -3168,6 +3168,9 @@ 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;
-- 
2.7.4

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  parent reply index

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-09-20  5:43 [PATCH v2 0/4] skip swapcache for super fast device Minchan Kim
2017-09-20  5:43 ` [PATCH v2 1/4] zram: set BDI_CAP_STABLE_WRITES once Minchan Kim
2017-09-20  5:43 ` [PATCH v2 2/4] bdi: introduce BDI_CAP_SYNCHRONOUS_IO Minchan Kim
2017-09-20  5:43 ` Minchan Kim [this message]
2017-09-20  5:43 ` [PATCH v2 4/4] mm:swap: skip swapcache for swapin of synchronous device Minchan Kim
2017-09-29  8:51   ` huang ying
2017-10-09  1:26     ` huang ying
2017-10-10  0:34     ` Minchan Kim
2017-10-10  1:10       ` Huang, Ying
  -- strict thread matches above, loose matches on Subject: below --
2017-09-19  7:09 [PATCH v2 0/4] skip swapcache for super fast device Minchan Kim
2017-09-19  7:10 ` [PATCH v2 3/4] mm:swap: introduce SWP_SYNCHRONOUS_IO Minchan Kim

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