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Jens Axboe 38cfb5a45e blk-wbt: improve waking of tasks
We have two potential issues:

1) After commit 2887e41b91, we only wake one process at the time when
   we finish an IO. We really want to wake up as many tasks as can
   queue IO. Before this commit, we woke up everyone, which could cause
   a thundering herd issue.

2) A task can potentially consume two wakeups, causing us to (in
   practice) miss a wakeup.

Fix both by providing our own wakeup function, which stops
__wake_up_common() from waking up more tasks if we fail to get a
queueing token. With the strict ordering we have on the wait list, this
wakes the right tasks and the right amount of tasks.

Based on a patch from Jianchao Wang <jianchao.w.wang@oracle.com>.

Tested-by: Agarwal, Anchal <anchalag@amazon.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-08-27 11:27:26 -06:00
Documentation Merge branch 'for-4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/libata 2018-08-24 13:20:33 -07:00
LICENSES LICENSES: Add Linux-OpenIB license text 2018-04-27 16:41:53 -06:00
arch IOMMU Update for Linux v4.19 2018-08-24 13:10:38 -07:00
block blk-wbt: improve waking of tasks 2018-08-27 11:27:26 -06:00
certs Replace magic for trusting the secondary keyring with #define 2018-08-16 09:57:20 -07:00
crypto DMAengine updates for v4.19-rc1 2018-08-18 15:55:59 -07:00
drivers for-linus-20180825 2018-08-25 13:30:23 -07:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs This pull request contains a single fix for UBIFS: 2018-08-25 13:27:35 -07:00
include Merge branch 'for-4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/libata 2018-08-24 13:20:33 -07:00
init Merge branch 'akpm' (patches from Andrew) 2018-08-22 12:34:08 -07:00
ipc ipc/util.c: update return value of ipc_getref from int to bool 2018-08-22 10:52:52 -07:00
kernel Merge branch 'for-4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup 2018-08-24 13:19:27 -07:00
lib lib/fonts: convert comments to utf-8 2018-08-23 18:48:43 -07:00
mm mm/cow: don't bother write protecting already write-protected pages 2018-08-25 13:15:03 -07:00
net Merge branch 'akpm' (patches from Andrew) 2018-08-23 19:20:12 -07:00
samples samples/bpf: all XDP samples should unload xdp/bpf prog on SIGTERM 2018-08-16 21:55:32 +02:00
scripts treewide: correct "differenciate" and "instanciate" typos 2018-08-23 18:48:43 -07:00
security + Cleanups 2018-08-24 13:00:33 -07:00
sound Merge branch 'akpm' (patches from Andrew) 2018-08-23 19:20:12 -07:00
tools treewide: convert ISO_8859-1 text comments to utf-8 2018-08-23 18:48:43 -07:00
usr kbuild: rename built-in.o to built-in.a 2018-03-26 02:01:19 +09:00
virt ARM: Support for Group0 interrupts in guests, Cache management 2018-08-22 13:52:44 -07:00
.clang-format clang-format: Set IndentWrappedFunctionNames false 2018-08-01 18:38:51 +02:00
.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 updates for v4.17 (2nd) 2018-04-15 17:21:30 -07:00
.mailmap Merge branch 'linus/master' into rdma.git for-next 2018-08-16 14:21:29 -06:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS 9p: remove Ron Minnich from MAINTAINERS 2018-08-17 16:20:26 -07:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
MAINTAINERS libata: maintainership update 2018-08-25 12:35:45 -07:00
Makefile Updates for v4.19: 2018-08-20 18:32:00 -07:00
README Docs: Added a pointer to the formatted docs to README 2018-03-21 09:02:53 -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.
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.