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Harshad Shirwadkar b84477d3eb blk-wbt: fix performance regression in wbt scale_up/scale_down
scale_up wakes up waiters after scaling up. But after scaling max, it
should not wake up more waiters as waiters will not have anything to
do. This patch fixes this by making scale_up (and also scale_down)
return when threshold is reached.

This bug causes increased fdatasync latency when fdatasync and dd
conv=sync are performed in parallel on 4.19 compared to 4.14. This
bug was introduced during refactoring of blk-wbt code.

Fixes: a79050434b ("blk-rq-qos: refactor out common elements of blk-wbt")
Cc: stable@vger.kernel.org
Cc: Josef Bacik <jbacik@fb.com>
Signed-off-by: Harshad Shirwadkar <harshadshirwadkar@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-10-06 09:26:41 -06:00
Documentation The highlights are: 2019-09-25 10:21:13 -07:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
arch Merge branch 'akpm' (patches from Andrew) 2019-09-24 16:10:23 -07:00
block blk-wbt: fix performance regression in wbt scale_up/scale_down 2019-10-06 09:26:41 -06:00
certs Revert "Merge tag 'keys-acl-20190703' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs" 2019-07-10 18:43:43 -07:00
crypto - crypto and DM crypt advances that allow the crypto API to reclaim 2019-09-21 10:40:37 -07:00
drivers Revert "libata, freezer: avoid block device removal while system is frozen" 2019-10-06 09:11:37 -06:00
fs io_uring: fix reversed nonblock flag for link submission 2019-10-04 08:31:15 -06:00
include block: pg: add header include guard 2019-10-02 20:32:27 -06:00
init mm: use CPU_BITS_NONE to initialize init_mm.cpu_bitmask 2019-09-24 15:54:10 -07:00
ipc Merge branch 'work.mount-base' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2019-09-18 13:15:58 -07:00
kernel Revert "libata, freezer: avoid block device removal while system is frozen" 2019-10-06 09:11:37 -06:00
lib mm: remove quicklist page table caches 2019-09-24 15:54:09 -07:00
mm bdi: Do not use freezable workqueue 2019-10-06 09:11:35 -06:00
net The highlights are: 2019-09-25 10:21:13 -07:00
samples rpmsg updates for v5.4 2019-09-22 10:58:15 -07:00
scripts Modules updates for v5.4 2019-09-22 10:34:46 -07:00
security KEYS: trusted: correctly initialize digests and fix locking issue 2019-09-25 02:43:53 +03:00
sound sound fixes for 5.4-rc1 2019-09-24 16:46:16 -07:00
tools tpmdd fixes for Linux v5.4 2019-09-25 09:40:24 -07:00
usr kbuild: clean compressed initramfs image 2019-09-24 15:54:07 -07:00
virt * s390: ioctl hardening, selftests 2019-09-18 09:49:13 -07:00
.clang-format clang-format: Update with the latest for_each macro list 2019-08-31 10:00:51 +02:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Modules updates for v5.4 2019-09-22 10:34:46 -07:00
.mailmap Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next 2019-09-18 12:34:53 -07:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS CREDITS: Update email address 2019-09-13 17:21:38 +03:00
Kbuild kbuild: do not descend to ./Kbuild when cleaning 2019-08-21 21:03:58 +09:00
Kconfig docs: kbuild: convert docs to ReST and rename to *.rst 2019-06-14 14:21:21 -06:00
MAINTAINERS tpmdd fixes for Linux v5.4 2019-09-25 09:40:24 -07:00
Makefile Modules updates for v5.4 2019-09-22 10:34:46 -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.