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Message #03335
[Bug 1136700] Re: cpufreq ondemand governor problem
James Hochschild, could you please test the latest upstream kernel available following https://wiki.ubuntu.com/KernelMainlineBuilds ? It will allow additional upstream developers to examine the issue. Please do not test the daily folder, but the one all the way at the bottom. Once you've tested the upstream kernel, please comment on which kernel version specifically you tested. If this bug is fixed in the mainline kernel, please add the following tags:
kernel-fixed-upstream
kernel-fixed-upstream-VERSION-NUMBER
where VERSION-NUMBER is the version number of the kernel you tested. For example:
kernel-fixed-upstream-v3.11-rc3
This can be done by clicking on the yellow circle with a black pencil icon next to the word Tags located at the bottom of the bug description. As well, please remove the tag:
needs-upstream-testing
If the mainline kernel does not fix this bug, please add the following tags:
kernel-bug-exists-upstream
kernel-bug-exists-upstream-VERSION-NUMBER
As well, please remove the tag:
needs-upstream-testing
If you are unable to test the mainline kernel, please comment as to why specifically you were unable to test it and add the following tags:
kernel-unable-to-test-upstream
kernel-unable-to-test-upstream-VERSION-NUMBER
Once testing of the upstream kernel is complete, please mark this bug's
Status as Confirmed. Please let us know your results. Thank you for your
understanding.
** Tags removed: kernel-bug-exists-upstream
** Tags added: kernel-bug-exists-upstream-v3.9-rc1 latest-bios-f9 needs-upstream-testing regression-potential
** Changed in: linux (Ubuntu)
Status: Confirmed => Incomplete
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https://bugs.launchpad.net/bugs/1136700
Title:
cpufreq ondemand governor problem
Status in “linux” package in Ubuntu:
Incomplete
Bug description:
I'm seeing a problem with the cpufreq ondemand governor in 12.04 32-bit. When I
load one core of my Intel i5-3570 processor, instead of switching to a steady
3.8GHz clock as I would expect, the clock actually toggles between 1.6GHz (min
frequency) and 3.8GHz (max frequency), even though the core is maxed out at
100%. I can increase the time it spends at 3.8GHz by increasing the
sampling_down_factor tuning parameter, but it still switches back to 1.6GHz,
albeit less frequently. I've also tried 12.10 32-bit and it has the same
problem. However, 12.04 and 12.10 64-bit do not have the problem. I decided to
look into this a little further, so I copied the source code for the ondemand
governor module and added a little debug code to see what was going on. I found
that the __cpufreq_driver_getavg function call was sometimes returning a value
which was several orders of magnitude too small. For example:
[20174.251637] mygov: freq_avg(2) = 158 freq_cur = 3801000
[20174.251642] mygov: freq_avg(0) = 4149919 freq_cur = 1600000
[20174.251645] mygov: freq_avg(1) = 4149919 freq_cur = 1600000
[20174.251647] mygov: freq_avg(3) = 4120224 freq_cur = 1600000
As you can see, the return value freq_avg is very small for core 2, which is the
maxed out core. This value is calculated in mperf.c using 32-bit unsigned
integers (in the 32-bit OS case) and it includes a final 10-bit right shift. As
you can see, the normal return value is greater than 4meg, so before the shift it
is greater then 4gig, right at the limit of a 32-bit integer. I believe that the
erroneous return values are due to 32-bit overflow in the average frequency
calculation. However, in the 64-bit OS the calculation uses 64 bits since one of
the variables is declared as unsigned long, so there is no overflow. Note that
slower processors wouldn't show this problem since the average frequency numbers
would be smaller. Also, I have noticed that if I load 3 or 4 cores, the problem
disappears. This is because the processor maximum clock frequency is
automatically reduced to 3.7GHz or 3.6GHz respectively, and this frequency
reduction is enough to avoid overflow.
ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: linux-image-3.2.0-38-generic-pae 3.2.0-38.61
ProcVersionSignature: Ubuntu 3.2.0-38.61-generic-pae 3.2.37
Uname: Linux 3.2.0-38-generic-pae i686
AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.24.
ApportVersion: 2.0.1-0ubuntu17.1
Architecture: i386
ArecordDevices:
**** List of CAPTURE Hardware Devices ****
card 0: AudioPCI [Ensoniq AudioPCI], device 0: ES1371/1 [ES1371 DAC2/ADC]
Subdevices: 1/1
Subdevice #0: subdevice #0
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC0: jim 2351 F.... pulseaudio
jim 3333 F.... xmms
/dev/snd/pcmC0D0p: jim 2351 F...m pulseaudio
CRDA: Error: command ['iw', 'reg', 'get'] failed with exit code 1: nl80211 not found.
Card0.Amixer.info:
Card hw:0 'AudioPCI'/'Ensoniq AudioPCI ENS1371 at 0xd000, irq 18'
Mixer name : 'SigmaTel STAC9721,23'
Components : 'AC97a:83847609'
Controls : 36
Simple ctrls : 23
Date: Thu Feb 28 18:49:55 2013
HibernationDevice: RESUME=UUID=9c9d7935-45a9-4dae-8d56-b28be920ca4e
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Release i386 (20120423)
IwConfig:
lo no wireless extensions.
eth0 no wireless extensions.
MachineType: Gigabyte Technology Co., Ltd. To be filled by O.E.M.
MarkForUpload: True
ProcEnviron:
TERM=xterm
LC_COLLATE=POSIX
PATH=(custom, no user)
LANG=en_US.UTF-8
SHELL=/usr/bin/tcsh
ProcFB:
0 inteldrmfb
1 VESA VGA
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.2.0-38-generic-pae root=UUID=8d75fd4b-1bf6-4edc-9f5b-57790e729fe1 ro vga=791 debug ignore_loglevel
RelatedPackageVersions:
linux-restricted-modules-3.2.0-38-generic-pae N/A
linux-backports-modules-3.2.0-38-generic-pae N/A
linux-firmware 1.79.1
RfKill:
SourcePackage: linux
StagingDrivers: mei
UpgradeStatus: No upgrade log present (probably fresh install)
WifiSyslog:
Feb 28 10:40:13 elrond NetworkManager[1083]: <info> Unmanaged Device found; state CONNECTED forced. (see http://bugs.launchpad.net/bugs/191889)
Feb 28 10:40:36 elrond NetworkManager[1083]: <info> Unmanaged Device found; state CONNECTED forced. (see http://bugs.launchpad.net/bugs/191889)
Feb 28 12:21:03 elrond NetworkManager[1083]: <info> Unmanaged Device found; state CONNECTED forced. (see http://bugs.launchpad.net/bugs/191889)
Feb 28 12:21:14 elrond NetworkManager[1083]: <info> Unmanaged Device found; state CONNECTED forced. (see http://bugs.launchpad.net/bugs/191889)
Feb 28 16:28:23 elrond NetworkManager[1083]: <info> Unmanaged Device found; state CONNECTED forced. (see http://bugs.launchpad.net/bugs/191889)
dmi.bios.date: 08/22/2012
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: F9
dmi.board.asset.tag: To be filled by O.E.M.
dmi.board.name: H77M-D3H
dmi.board.vendor: Gigabyte Technology Co., Ltd.
dmi.board.version: x.x
dmi.chassis.asset.tag: To Be Filled By O.E.M.
dmi.chassis.type: 3
dmi.chassis.vendor: Gigabyte Technology Co., Ltd.
dmi.chassis.version: To Be Filled By O.E.M.
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrF9:bd08/22/2012:svnGigabyteTechnologyCo.,Ltd.:pnTobefilledbyO.E.M.:pvrTobefilledbyO.E.M.:rvnGigabyteTechnologyCo.,Ltd.:rnH77M-D3H:rvrx.x:cvnGigabyteTechnologyCo.,Ltd.:ct3:cvrToBeFilledByO.E.M.:
dmi.product.name: To be filled by O.E.M.
dmi.product.version: To be filled by O.E.M.
dmi.sys.vendor: Gigabyte Technology Co., Ltd.
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