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Rafael J. Wysocki 757ab15c3f cpuidle: menu: Retain tick when shallow state is selected 
The case addressed by commit 5ef499cd57 (cpuidle: menu: Handle
stopped tick more aggressively) in the stopped tick case is present
when the tick has not been stopped yet too.  Namely, if only two CPU
idle states, shallow state A with target residency significantly
below the tick boundary and deep state B with target residency
significantly above it, are available and the predicted idle
duration is above the tick boundary, but below the target residency
of state B, state A will be selected and the CPU may spend indefinite
amount of time in it, which is not quite energy-efficient.

However, if the tick has not been stopped yet and the governor is
about to select a shallow idle state for the CPU even though the idle
duration predicted by it is above the tick boundary, it should be
fine to wake up the CPU early, so the tick can be retained then and
the governor will have a chance to select a deeper state when it runs
next time.

[Note that when this really happens, it will make the idle duration
 predictor believe that the CPU might be idle longer than predicted,
 which will make it more likely to predict longer idle durations going
 forward, but that will also cause deeper idle states to be selected
 going forward, on average, which is what's needed here.]

Fixes: 87c9fe6ee4 (cpuidle: menu: Avoid selecting shallow states with stopped tick)
Reported-by: Leo Yan <leo.yan@linaro.org>
Cc: 4.17+ <stable@vger.kernel.org> # 4.17+: 5ef499cd57 (cpuidle: menu: Handle ...)
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
 		2018-08-25 13:16:08 +02:00
Documentation overlayfs update for 4.19 2018-08-21 18:19:09 -07:00
LICENSES LICENSES: Add Linux-OpenIB license text 2018-04-27 16:41:53 -06:00
arch More power management updates for 4.19-rc1 2018-08-22 07:42:36 -07:00
block for-4.19/block-20180812 2018-08-14 10:23:25 -07:00
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 cpuidle: menu: Retain tick when shallow state is selected 2018-08-25 13:16:08 +02:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs fuse update for 4.19 2018-08-21 18:47:36 -07:00
include overlayfs update for 4.19 2018-08-21 18:19:09 -07:00
init Merge branch 'siginfo-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2018-08-21 13:47:29 -07:00
ipc Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2018-08-15 15:04:25 -07:00
kernel More power management updates for 4.19-rc1 2018-08-22 07:42:36 -07:00
lib Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-08-19 11:51:45 -07:00
mm Merge branch 'siginfo-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2018-08-21 13:47:29 -07:00
net The main things are support for cephx v2 authentication protocol and 2018-08-20 18:26:55 -07:00
samples samples/bpf: all XDP samples should unload xdp/bpf prog on SIGTERM 2018-08-16 21:55:32 +02:00
scripts Updates for v4.19: 2018-08-20 18:32:00 -07:00
security Merge branch 'next-integrity' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2018-08-15 22:54:12 -07:00
sound DMAengine updates for v4.19-rc1 2018-08-18 15:55:59 -07:00
tools linux-kselftest-4.19-rc1 2018-08-20 19:02:17 -07:00
usr kbuild: rename built-in.o to built-in.a 2018-03-26 02:01:19 +09:00
virt Merge branch 'siginfo-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2018-08-21 13:47:29 -07:00
.clang-format clang-format: Set IndentWrappedFunctionNames false 2018-08-01 18:38:51 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Add hch to .get_maintainer.ignore 2015-08-21 14:30:10 -07:00
.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 power supply and reset changes for the v4.19 series 2018-08-21 18:06:27 -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.