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Minchan Kim 0bcac06f27 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>
2017-11-15 18:21:02 -08:00
arch m32r: fix endianness constraints 2017-11-15 18:21:00 -08:00
block block/blk-mq.c: use kmalloc_array_node() 2017-11-15 18:21:02 -08:00
certs License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2017-11-14 10:52:09 -08:00
Documentation arm64 updates for 4.15 2017-11-15 10:56:56 -08:00
drivers bdi: introduce BDI_CAP_SYNCHRONOUS_IO 2017-11-15 18:21:02 -08:00
firmware License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
fs slab, slub, slob: add slab_flags_t 2017-11-15 18:21:01 -08:00
include mm, swap: skip swapcache for swapin of synchronous device 2017-11-15 18:21:02 -08:00
init mm: slabinfo: remove CONFIG_SLABINFO 2017-11-15 18:21:01 -08:00
ipc License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
kernel arm64 updates for 4.15 2017-11-15 10:56:56 -08:00
lib RISC-V Port for Linux 4.15 v9 2017-11-15 10:49:15 -08:00
mm mm, swap: skip swapcache for swapin of synchronous device 2017-11-15 18:21:02 -08:00
net net/rds/ib_fmr.c: use kmalloc_array_node() 2017-11-15 18:21:02 -08:00
samples Merge branch 'for-linus' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/jikos/livepatching 2017-11-15 10:21:58 -08:00
scripts bloat-o-meter: provide 3 different arguments for data, function and All 2017-11-15 18:21:00 -08:00
security Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2017-11-14 10:52:09 -08:00
sound sound updates for 4.15-rc1 2017-11-14 18:01:46 -08:00
tools tools: slabinfo: add "-U" option to show unreclaimable slabs only 2017-11-15 18:21:01 -08:00
usr initramfs: fix initramfs rebuilds w/ compression after disabling 2017-11-03 07:39:19 -07:00
virt arm64 updates for 4.15 2017-11-15 10:56:56 -08:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore .gitignore: move *.dtb and *.dtb.S patterns to the top-level .gitignore 2017-11-08 11:20:24 -06:00
.mailmap .mailmap: Add Maciej W. Rozycki's Imagination e-mail address 2017-11-10 12:16:15 -08:00
COPYING
CREDITS MAINTAINERS: update TPM driver infrastructure changes 2017-11-09 17:58:40 -08:00
Kbuild License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
Kconfig License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
MAINTAINERS arm64 updates for 4.15 2017-11-15 10:56:56 -08:00
Makefile RISC-V Port for Linux 4.15 v9 2017-11-15 10:49:15 -08:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

Linux kernel
============

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.