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Filename Latest commit message Latest commit date
NeilBrown 480523feae md: only call set_in_sync() when it is expected to succeed.
Since commit 4ad23a9764 ("MD: use per-cpu counter for
writes_pending"), set_in_sync() is substantially more expensive: it
can wait for a full RCU grace period which can be 10s of milliseconds.

So we should only call it when the cost is justified.

md_check_recovery() currently calls set_in_sync() every time it finds
anything to do (on non-external active arrays).  For an array
performing resync or recovery, this will be quite often.
Each call will introduce a delay to the md thread, which can noticeable
affect IO submission latency.

In md_check_recovery() we only need to call set_in_sync() if
'safemode' was non-zero at entry, meaning that there has been not
recent IO.  So we save this "safemode was nonzero" state, and only
call set_in_sync() if it was non-zero.

This measurably reduces mean and maximum IO submission latency during
resync/recovery.

Reported-and-tested-by: Jack Wang <jinpu.wang@cloud.ionos.com>
Fixes: 4ad23a9764 ("MD: use per-cpu counter for writes_pending")
Cc: stable@vger.kernel.org (v4.12+)
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Song Liu <songliubraving@fb.com>
2019-08-27 12:36:36 -07:00
arch powerpc fixes for 5.3 #3 2019-08-04 10:30:47 -07:00
block block: move same page handling from __bio_add_pc_page to the callers 2019-08-22 07:14:39 -06:00
certs
crypto
Documentation HMM patches for 5.3-rc 2019-07-30 12:54:44 -07:00
drivers md: only call set_in_sync() when it is expected to succeed. 2019-08-27 12:36:36 -07:00
fs writeback, memcg: Implement cgroup_writeback_by_id() 2019-08-27 09:22:38 -06:00
include writeback, memcg: Implement foreign dirty flushing 2019-08-27 09:22:38 -06:00
init Merge branch 'work.mount0' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2019-07-19 10:42:02 -07:00
ipc Merge branch 'work.mount0' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2019-07-19 10:42:02 -07:00
kernel memremap: move from kernel/ to mm/ 2019-08-03 07:02:01 -07:00
lib lib: scatterlist: Fix to support no mapped sg 2019-08-08 07:45:01 -06:00
LICENSES
mm writeback, memcg: Implement foreign dirty flushing 2019-08-27 09:22:38 -06:00
net tcp: be more careful in tcp_fragment() 2019-07-21 20:41:24 -07:00
samples treewide: remove SPDX "WITH Linux-syscall-note" from kernel-space headers again 2019-07-25 11:05:10 +02:00
scripts kconfig: Clear "written" flag to avoid data loss 2019-08-04 12:44:15 +09:00
security selinux/stable-5.3 PR 20190801 2019-08-02 18:40:49 -07:00
sound sound fixes for 5.3-rc3 2019-08-02 08:53:34 -07:00
tools Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-08-03 10:58:46 -07:00
usr kbuild: enable arch/s390/include/uapi/asm/zcrypt.h for uapi header test 2019-07-23 10:45:46 +02:00
virt Documentation: move Documentation/virtual to Documentation/virt 2019-07-24 10:52:11 +02:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore .gitignore: Add compilation database file 2019-07-27 12:18:19 +09:00
.mailmap MAINTAINERS: Update my email address 2019-07-22 14:57:50 +01:00
COPYING
CREDITS Remove references to dead website. 2019-07-19 12:22:04 -07:00
Kbuild
Kconfig
MAINTAINERS MAINTAINERS: Add Geert as Renesas SoC Co-Maintainer 2019-08-04 10:23:23 -07:00
Makefile Linux 5.3-rc3 2019-08-04 18:40:12 -07:00
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.