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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:#1F497D">This may be related to the CentOS CPU issue; perhaps it’s a problem in CFS itself, or Ubuntu has different policies so it’s not always triggered?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:#1F497D">-Michael<o:p></o:p></span></p>
<p class="MsoNormal"><br>
** Changed in: linux (Ubuntu)<br>
Status: New => Confirmed<o:p></o:p></p>
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--<br>
You received this bug notification because you are subscribed to the bug<br>
report.<br>
<a href="https://bugs.launchpad.net/bugs/1058854" target="_blank">https://bugs.launchpad.net/bugs/1058854</a><br>
<br>
Title:<br>
High CPU usage of CFS<br>
<br>
Status in “linux” package in Ubuntu:<o:p></o:p></p>
</div>
<p class="MsoNormal"> Confirmed<o:p></o:p></p>
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<div>
<p class="MsoNormal"><br>
Bug description:<br>
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:<br>
<a href="http://www.github.com/daveisfera/test_sleep/" target="_blank">www.github.com/daveisfera/test_sleep/</a><br>
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.<br>
<br>
I have also attached the results from running this test on an HP<br>
Pavilion dm4 and I believe that the gap at the low number of threads<br>
is caused by either the processor going into a power saving state<br>
because of the sleeping and/or a poor interaction with HyperThreading<br>
(scheduling the 2 threads on logical cores rather than separate<br>
physical cores).<br>
<br>
Because of this, I then ran 4 instances of:<br>
schedtool -a <CPU#> -e nice -19 yes > /dev/null<br>
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.<br>
<br>
ProblemType: Bug<br>
DistroRelease: Ubuntu 12.04<br>
Package: linux-image-3.2.0-31-generic 3.2.0-31.50<br>
ProcVersionSignature: Ubuntu 3.2.0-31.50-generic 3.2.28<br>
Uname: Linux 3.2.0-31-generic x86_64<br>
AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.24.<br>
ApportVersion: 2.0.1-0ubuntu13<br>
Architecture: amd64<br>
ArecordDevices:<br>
**** List of CAPTURE Hardware Devices ****<br>
card 0: PCH [HDA Intel PCH], device 0: STAC92xx Analog [STAC92xx Analog]<br>
Subdevices: 1/1<br>
Subdevice #0: subdevice #0<br>
AudioDevicesInUse:<br>
USER PID ACCESS COMMAND<br>
/dev/snd/controlC0: dlj 1778 F.... pulseaudio<br>
<a href="http://Card0.Amixer.info" target="_blank">Card0.Amixer.info</a>:<br>
Card hw:0 'PCH'/'HDA Intel PCH at 0xc0800000 irq 50'<br>
Mixer name : 'Intel CougarPoint HDMI'<br>
Components : 'HDA:111d76e0,103c1793,00100102 HDA:80862805,103c1793,00100000'<br>
Controls : 22<br>
Simple ctrls : 10<br>
Date: Fri Sep 28 20:57:35 2012<br>
InstallationMedia: Ubuntu 12.04.1 LTS "Precise Pangolin" - Release amd64 (20120823.1)<br>
MachineType: Hewlett-Packard HP Pavilion dm4 Notebook PC<br>
ProcEnviron:<br>
TERM=xterm<br>
PATH=(custom, no user)<br>
LANG=en_US.UTF-8<br>
SHELL=/bin/bash<br>
ProcFB: 0 inteldrmfb<br>
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.2.0-31-generic root=UUID=162256F02256D479 loop=/hostname/disks/root.disk ro quiet splash vt.handoff=7<br>
RelatedPackageVersions:<br>
linux-restricted-modules-3.2.0-31-generic N/A<br>
linux-backports-modules-3.2.0-31-generic N/A<br>
linux-firmware 1.79.1<br>
SourcePackage: linux<br>
StagingDrivers: rts_pstor mei<br>
UpgradeStatus: No upgrade log present (probably fresh install)<br>
dmi.bios.date: 01/17/2012<br>
dmi.bios.vendor: Hewlett-Packard<br>
dmi.bios.version: F.08<br>
dmi.board.asset.tag: Base Board Asset Tag<br>
<a href="http://dmi.board.name" target="_blank">dmi.board.name</a>: 1793<br>
dmi.board.vendor: Hewlett-Packard<br>
dmi.board.version: 41.1C<br>
dmi.chassis.asset.tag: Chassis Asset Tag<br>
dmi.chassis.type: 10<br>
dmi.chassis.vendor: Hewlett-Packard<br>
dmi.chassis.version: Chassis Version<br>
dmi.modalias: dmi:bvnHewlett-Packard:bvrF.08:bd01/17/2012:svnHewlett-Packard:pnHPPaviliondm4NotebookPC:pvr068E100002204710000622100:rvnHewlett-Packard:rn1793:rvr41.1C:cvnHewlett-Packard:ct10:cvrChassisVersion:<br>
<a href="http://dmi.product.name" target="_blank">dmi.product.name</a>: HP Pavilion dm4 Notebook PC<br>
dmi.product.version: 068E100002204710000622100<br>
dmi.sys.vendor: Hewlett-Packard<br>
<br>
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