linux-stable

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NeilBrown 2bc13b83e6 md: batch flush requests. Currently if many flush requests are submitted to an md device is quick succession, they are serialized and can take a long to process them all. We don't really need to call flush all those times - a single flush call can satisfy all requests submitted before it started. So keep track of when the current flush started and when it finished, allow any pending flush that was requested before the flush started to complete without waiting any more. Test results from Xiao: Test is done on a raid10 device which is created by 4 SSDs. The tool is dbench. 1. The latest linux stable kernel Operation Count AvgLat MaxLat -------------------------------------------------- Deltree 768 10.509 78.305 Flush 2078376 0.013 10.094 Close 21787697 0.019 18.821 LockX 96580 0.007 3.184 Mkdir 384 0.008 0.062 Rename 1255883 0.191 23.534 ReadX 46495589 0.020 14.230 WriteX 14790591 7.123 60.706 Unlink 5989118 0.440 54.551 UnlockX 96580 0.005 2.736 FIND_FIRST 10393845 0.042 12.079 SET_FILE_INFORMATION 2415558 0.129 10.088 QUERY_FILE_INFORMATION 4711725 0.005 8.462 QUERY_PATH_INFORMATION 26883327 0.032 21.715 QUERY_FS_INFORMATION `4929409` 0.010 8.238 NTCreateX 29660080 0.100 53.268 Throughput 1034.88 MB/sec (sync open) 128 clients 128 procs max_latency=60.712 ms 2. With patch1 "Revert "MD: fix lock contention for flush bios"" Operation Count AvgLat MaxLat -------------------------------------------------- Deltree 256 8.326 36.761 Flush 693291 3.974 180.269 Close 7266404 0.009 36.929 LockX 32160 0.006 0.840 Mkdir 128 0.008 0.021 Rename 418755 0.063 29.945 ReadX 15498708 0.007 7.216 WriteX 4932310 22.482 267.928 Unlink 1997557 0.109 47.553 UnlockX 32160 0.004 1.110 FIND_FIRST 3465791 0.036 7.320 SET_FILE_INFORMATION 805825 0.015 1.561 QUERY_FILE_INFORMATION 1570950 0.005 2.403 QUERY_PATH_INFORMATION `8965483` 0.013 14.277 QUERY_FS_INFORMATION 1643626 0.009 3.314 NTCreateX 9892174 0.061 41.278 Throughput 345.009 MB/sec (sync open) 128 clients 128 procs max_latency=267.939 m 3. With patch1 and patch2 Operation Count AvgLat MaxLat -------------------------------------------------- Deltree 768 9.570 54.588 Flush 2061354 0.666 15.102 Close 21604811 0.012 25.697 LockX 95770 0.007 1.424 Mkdir 384 0.008 0.053 Rename 1245411 0.096 12.263 ReadX 46103198 0.011 12.116 WriteX 14667988 7.375 60.069 Unlink 5938936 0.173 30.905 UnlockX 95770 0.005 4.147 FIND_FIRST 10306407 0.041 11.715 SET_FILE_INFORMATION 2395987 0.048 7.640 QUERY_FILE_INFORMATION 4672371 0.005 9.291 QUERY_PATH_INFORMATION 26656735 0.018 19.719 QUERY_FS_INFORMATION 4887940 0.010 7.654 NTCreateX 29410811 0.059 28.551 Throughput 1026.21 MB/sec (sync open) 128 clients 128 procs max_latency=60.075 ms Cc: <stable@vger.kernel.org> # v4.19+ Tested-by: Xiao Ni <xni@redhat.com> Signed-off-by: NeilBrown <neilb@suse.com> Signed-off-by: Song Liu <songliubraving@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>		2019-04-01 12:11:48 -06:00
arch	A collection of x86 and ARM bugfixes, and some improvements to documentation.	2019-03-31 08:55:59 -07:00
block	block: don't check if adjacent bvecs in one bio can be mergeable	2019-04-01 12:11:48 -06:00
certs	kexec, KEYS: Make use of platform keyring for signature verify	2019-02-04 17:34:07 -05:00
crypto	lib/lzo: separate lzo-rle from lzo	2019-03-07 18:32:03 -08:00
Documentation	doc, block, bfq: add information on bfq execution time	2019-04-01 08:15:40 -06:00
drivers	md: batch flush requests.	2019-04-01 12:11:48 -06:00
fs	Merge branch 'akpm' (patches from Andrew)	2019-03-29 16:02:28 -07:00
include	block: put the same page when adding it to bio	2019-04-01 12:11:34 -06:00
init	init/main: add checks for the return value of memblock_alloc*()	2019-03-12 10:04:02 -07:00
ipc	Merge branch 'work.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2019-03-12 14:08:19 -07:00
kernel	Merge branch 'smp-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2019-03-31 08:22:12 -07:00
lib	for-linus-20190329	2019-03-29 14:43:07 -07:00
LICENSES	LICENSES: Add GCC runtime library exception text	2019-01-16 14:54:15 -07:00
mm	mm/migrate.c: add missing flush_dcache_page for non-mapped page migrate	2019-03-29 10:01:37 -07:00
net	A patch to avoid choking on multipage bvecs in the messenger and	2019-03-29 14:41:09 -07:00
samples	Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net	2019-03-11 08:54:01 -07:00
scripts	Merge branch 'akpm' (patches from Andrew)	2019-03-29 16:02:28 -07:00
security	LSM: Revive CONFIG_DEFAULT_SECURITY_* for "make oldconfig"	2019-03-29 14:08:49 -07:00
sound	sound fixes for 5.1-rc3	2019-03-29 14:53:33 -07:00
tools	A collection of x86 and ARM bugfixes, and some improvements to documentation.	2019-03-31 08:55:59 -07:00
usr	user/Makefile: Fix typo and capitalization in comment section	2018-12-11 00:18:03 +09:00
virt	KVM/ARM fixes for 5.1	2019-03-28 19:07:30 +01:00
.clang-format	Merge branch 'work.iov_iter' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2019-03-12 13:43:42 -07:00
.cocciconfig
.get_maintainer.ignore
.gitattributes	.gitattributes: set git diff driver for C source code files	2016-10-07 18:46:30 -07:00
.gitignore	kbuild: Add support for DT binding schema checks	2018-12-13 09:41:32 -06:00
.mailmap	mailmap: add Changbin Du	2019-03-29 10:01:37 -07:00
COPYING	COPYING: use the new text with points to the license files	2018-03-23 12:41:45 -06:00
CREDITS	Char/Misc driver patches for 5.1-rc1	2019-03-06 14:18:59 -08:00
Kbuild	Kbuild updates for v5.1	2019-03-10 17:48:21 -07:00
Kconfig	kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt	2018-08-02 08:06:55 +09:00
MAINTAINERS	Merge branch 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2019-03-31 07:48:58 -07:00
Makefile	Linux 5.1-rc3	2019-03-31 14:39:29 -07:00
README	Drop all 00-INDEX files from Documentation/	2018-09-09 15:08:58 -06:00

README

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

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

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.