Bug 5133

Summary:	Ondemand governor makes system unstable
Product:	Power Management	Reporter:	Juha Heljoranta (juha)
Component:	cpufreq	Assignee:	cpufreq (cpufreq)
Status:	CLOSED CODE_FIX
Severity:	high	CC:	diegocg, kernel
Priority:	P2
Hardware:	i386
OS:	Linux
Kernel Version:	2.6.13-rc7	Subsystem:
Regression:	---	Bisected commit-id:
Attachments:	backtraces from 2.6.12-gentoo-r9 kernel-2.6.12-gentoo-r9 config backtrace from 2.6.13-rc7 backtrace from 2.6.13

Description Juha Heljoranta 2005-08-26 12:50:51 UTC

Distribution: Gentoo
Hardware Environment: x86_64
Software Environment:
Problem Description: When using ondemand governor the kernel will freeze, reboot
or most of the processes just become unstable after some time of usage.

Steps to reproduce:

start to use ondemand governor:
echo ondemand >/sys/devices/system/cpu/cpu0/cpufreq/scaling_governor

After some hours, say 1 - 4 h, the system becomes unstable when used normally
(surf net, read mail, etc.)


Symptoms:
System might reboot itself without warning, kill X, make some process to behave
oddly before the process dies, etc.

Normally there is no warnings, errors or what so ever. After enabling a kernel
debug I got few backtraces.


If I do not use the ondemand governor then the system works just fine (uptime
+30 days). I haven't changed my kernel configuration for some time so it was
quite easy to spot what caused system to freek out.


I recall that I've seen the same symptoms when using some 2.6.9 - 2.6.10
(Gentoo) kernels with ondemand governor. Back then I just decided to stick with
the default (performance) governor.

Comment 1 Juha Heljoranta 2005-08-26 13:02:07 UTC

Created attachment 5774 [details]
backtraces from 2.6.12-gentoo-r9

Comment 2 Juha Heljoranta 2005-08-26 13:03:06 UTC

Created attachment 5775 [details]
kernel-2.6.12-gentoo-r9 config

Comment 3 Juha Heljoranta 2005-08-26 13:04:22 UTC

Created attachment 5776 [details]
backtrace from 2.6.13-rc7

Comment 4 Juha Heljoranta 2005-08-26 13:08:30 UTC

Note that the system didn't start to show symptoms immediatetly after backtraces
appeared, but little while after messages (like hour or two).

Comment 5 Juha Heljoranta 2005-08-31 10:42:52 UTC

Created attachment 5831 [details]
backtrace from 2.6.13

I enabled cpufreq debug but I haven't noticed anything interesting, except lot
of 'printk: xx messages suppressed' -messages.

Is there anything that I could do to get this bug fixed?

Comment 6 Daniel Drake 2005-09-17 10:11:16 UTC

Downstream bug report: http://bugs.gentoo.org/show_bug.cgi?id=103497

Comment 7 Diego Calleja 2006-07-30 08:48:33 UTC

What is the state of this bug?

Comment 8 Daniel Drake 2007-04-29 07:03:31 UTC

no response from reporter, marking as NEEDINFO

Comment 9 Juha Heljoranta 2007-04-29 07:37:02 UTC

It seems that the ondemand cpufreq scaling governor has been fixed some where
between 2.6.14 and 2.6.17. Ondemand governor has been my default cpu frequency
governor at least since 2.6.18. I might have used it with 2.6.17.
IIRC I tried to use ondemand with 2.6.14 and 2.6.15 but with same symptoms.

Comment 10 Daniel Drake 2007-04-29 07:51:45 UTC

Great, thanks for the update.