[Kernel-packages] [Bug 1058854] Re: High CPU usage of CFS
I no longer have access to this hardware to get the full computer model,
but the referenced test programs should be able to reproduce the issue
on most, if not all machines (it's worked on everyone I've tried it on
to date).
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https://bugs.launchpad.net/bugs/1058854
Title:
High CPU usage of CFS
Status in “linux” package in Ubuntu:
Incomplete
Bug description:
It appears that there is an issue with the Completely Fair Scheduler (CFS)
not intereacting well with sleep commands. I have written up a test program to
help demonstrate the issue and it can be found at:
www.github.com/daveisfera/test_sleep/
The test outputs wall time (CPU clock), user time, and system time, but
usually only the wall time and user time outputs are meaningful because the
system time is so small and usually within the standard deviation for all tests.
I have also attached the results from running this test on an HP
Pavilion dm4 and I believe that the gap at the low number of threads
is caused by either the processor going into a power saving state
because of the sleeping and/or a poor interaction with HyperThreading
(scheduling the 2 threads on logical cores rather than separate
physical cores).
Because of this, I then ran 4 instances of:
schedtool -a CPU# -e nice -19 yes /dev/null
so that all of the cores would be kept busy during the sleeping and this had
an unexpected effect of causing the wall time to increase significantly. I am
not sure what the cause of the wall time increase is, but it does help the user
time plot display the gap between the sleep methods and the none sleep methods
that I believe is a symptom/display of the unexpectedly high CPU usage when the
process should be sleeping.
ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: linux-image-3.2.0-31-generic 3.2.0-31.50
ProcVersionSignature: Ubuntu 3.2.0-31.50-generic 3.2.28
Uname: Linux 3.2.0-31-generic x86_64
AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.24.
ApportVersion: 2.0.1-0ubuntu13
Architecture: amd64
ArecordDevices:
List of CAPTURE Hardware Devices
card 0: PCH [HDA Intel PCH], device 0: STAC92xx Analog [STAC92xx Analog]
Subdevices: 1/1
Subdevice #0: subdevice #0
AudioDevicesInUse:
USERPID ACCESS COMMAND
/dev/snd/controlC0: dlj1778 F pulseaudio
Card0.Amixer.info:
Card hw:0 'PCH'/'HDA Intel PCH at 0xc080 irq 50'
Mixer name : 'Intel CougarPoint HDMI'
Components : 'HDA:111d76e0,103c1793,00100102
HDA:80862805,103c1793,0010'
Controls : 22
Simple ctrls : 10
Date: Fri Sep 28 20:57:35 2012
InstallationMedia: Ubuntu 12.04.1 LTS Precise Pangolin - Release amd64
(20120823.1)
MachineType: Hewlett-Packard HP Pavilion dm4 Notebook PC
ProcEnviron:
TERM=xterm
PATH=(custom, no user)
LANG=en_US.UTF-8
SHELL=/bin/bash
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.2.0-31-generic
root=UUID=162256F02256D479 loop=/hostname/disks/root.disk ro quiet splash
vt.handoff=7
RelatedPackageVersions:
linux-restricted-modules-3.2.0-31-generic N/A
linux-backports-modules-3.2.0-31-generic N/A
linux-firmware1.79.1
SourcePackage: linux
StagingDrivers: rts_pstor mei
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 01/17/2012
dmi.bios.vendor: Hewlett-Packard
dmi.bios.version: F.08
dmi.board.asset.tag: Base Board Asset Tag
dmi.board.name: 1793
dmi.board.vendor: Hewlett-Packard
dmi.board.version: 41.1C
dmi.chassis.asset.tag: Chassis Asset Tag
dmi.chassis.type: 10
dmi.chassis.vendor: Hewlett-Packard
dmi.chassis.version: Chassis Version
dmi.modalias:
dmi:bvnHewlett-Packard:bvrF.08:bd01/17/2012:svnHewlett-Packard:pnHPPaviliondm4NotebookPC:pvr068E1220471622100:rvnHewlett-Packard:rn1793:rvr41.1C:cvnHewlett-Packard:ct10:cvrChassisVersion:
dmi.product.name: HP Pavilion dm4 Notebook PC
dmi.product.version: 068E1220471622100
dmi.sys.vendor: Hewlett-Packard
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[Kernel-packages] [Bug 1058864] Re: Poor mutex and semaphore performance
I no longer have access to this hardware to get the full computer model,
but the referenced test programs should be able to reproduce the issue
on most, if not all machines (it's worked on everyone I've tried it on
to date).
--
You received this bug notification because you are a member of Kernel
Packages, which is subscribed to linux in Ubuntu.
https://bugs.launchpad.net/bugs/1058864
Title:
Poor mutex and semaphore performance
Status in “linux” package in Ubuntu:
Incomplete
Bug description:
I noticed the results of this blog post:
http://mr-edd.co.uk/blog/sad_state_of_osx_pthread_mutex_t
and I was curious if the same sort of issue existed with the linux kernel and
if it would shed any light on Bug #1058854
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1058854
The results don't appear to be as bad as those seen on Mac OS X, but they
definitely are a lot poorer than I expected/hoped they would be. The code that
builds on Linux is now available on that blog port and I created a git repo
with the history here:
https://github.com/daveisfera/test_mutex
Here are the results from running it on the the same HP Pavilion dm4 that as
the results from Bug #1058854:
mutex
1 thread real 0m 0.514s user 0m 0.512s sys 0m 0.000s
2 threads real 0m 4.382s user 0m 5.176s sys 0m 3.544s
4 threads real 0m 9.953s user 0m 9.709s sys 0m22.417s
8 threads real 0m20.984s user 0m14.973s sys 1m 8.256s
16 threads real 0m38.725s user 0m28.426s sys 2m 5.484s
benaphore
1 thread real 0m 0.324s user 0m 0.312s sys 0m 0.008s
2 threads real 0m 6.372s user 0m 6.380s sys 0m 5.572s
4 threads real 0m17.820s user 0m12.273s sys 0m42.495s
8 threads real 0m40.266s user 0m25.626s sys 2m14.400s
16 threads real 1m40.090s user 0m52.939s sys 5m45.802s
mutex2
1 thread real 0m 0.325s user 0m 0.320s sys 0m 0.004s
2 threads real 0m 0.730s user 0m 0.816s sys 0m 0.384s
4 threads real 0m 2.328s user 0m 3.388s sys 0m 5.704s
8 threads real 0m 4.096s user 0m 5.328s sys 0m10.705s
16 threads real 0m 7.584s user 0m 9.609s sys 0m20.401s
---
AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.24.
ApportVersion: 2.0.1-0ubuntu13
Architecture: amd64
ArecordDevices:
List of CAPTURE Hardware Devices
card 0: PCH [HDA Intel PCH], device 0: STAC92xx Analog [STAC92xx Analog]
Subdevices: 1/1
Subdevice #0: subdevice #0
AudioDevicesInUse:
USERPID ACCESS COMMAND
/dev/snd/controlC0: dlj1876 F pulseaudio
Card0.Amixer.info:
Card hw:0 'PCH'/'HDA Intel PCH at 0xc080 irq 50'
Mixer name : 'Intel CougarPoint HDMI'
Components : 'HDA:111d76e0,103c1793,00100102
HDA:80862805,103c1793,0010'
Controls : 22
Simple ctrls : 10
DistroRelease: Ubuntu 12.04
InstallationMedia: Ubuntu 12.04.1 LTS Precise Pangolin - Release amd64
(20120823.1)
MachineType: Hewlett-Packard HP Pavilion dm4 Notebook PC
Package: linux (not installed)
ProcEnviron:
TERM=xterm
PATH=(custom, no user)
LANG=en_US.UTF-8
SHELL=/bin/bash
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.2.0-31-generic
root=UUID=162256F02256D479 loop=/hostname/disks/root.disk ro quiet splash
vt.handoff=7
ProcVersionSignature: Ubuntu 3.2.0-31.50-generic 3.2.28
RelatedPackageVersions:
linux-restricted-modules-3.2.0-31-generic N/A
linux-backports-modules-3.2.0-31-generic N/A
linux-firmware1.79.1
StagingDrivers: rts_pstor mei
Tags: precise running-unity staging
Uname: Linux 3.2.0-31-generic x86_64
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm cdrom dip lpadmin plugdev sambashare sudo
dmi.bios.date: 01/17/2012
dmi.bios.vendor: Hewlett-Packard
dmi.bios.version: F.08
dmi.board.asset.tag: Base Board Asset Tag
dmi.board.name: 1793
dmi.board.vendor: Hewlett-Packard
dmi.board.version: 41.1C
dmi.chassis.asset.tag: Chassis Asset Tag
dmi.chassis.type: 10
dmi.chassis.vendor: Hewlett-Packard
dmi.chassis.version: Chassis Version
dmi.modalias:
dmi:bvnHewlett-Packard:bvrF.08:bd01/17/2012:svnHewlett-Packard:pnHPPaviliondm4NotebookPC:pvr068E1220471622100:rvnHewlett-Packard:rn1793:rvr41.1C:cvnHewlett-Packard:ct10:cvrChassisVersion:
dmi.product.name: HP Pavilion dm4 Notebook PC
dmi.product.version: 068E1220471622100
dmi.sys.vendor: Hewlett-Packard
To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1058864/+subscriptions
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