Bug 14806

Summary:	cpufreq reports frequency of incorrect core on AMD Phenom(tm) II X3 720 Processor
Product:	Power Management	Reporter:	hkmaly
Component:	cpufreq	Assignee:	Mark Langsdorf (mark.langsdorf)
Status:	CLOSED PATCH_ALREADY_AVAILABLE
Severity:	normal	CC:	akpm, lenb, mark.langsdorf, nagananda.chumbalkar
Priority:	P1
Hardware:	All
OS:	Linux
Kernel Version:	2.6.30-gentoo-r8	Subsystem:
Regression:	No	Bisected commit-id:

Description hkmaly 2009-12-14 08:02:49 UTC

On AMD Phenom(tm) II X3 720 Processor with 2.6.30-gentoo-r8 (which should be equivalent to 2.6.30.9) seems to always report frequency of zeroth core as the "asserted by call to hardware" frequency cpufreq gets from /sys/devices/system/cpu/cpu*/cpufreq/cpuinfo_cur_freq, while frequency reported in /sys/devices/system/cpu/cpu*/cpufreq/scaling_cur_freq differs for different cores in a way which is confirmed by framerate of mencoder (so it really can change frequency of cores independently).

(Noticed with governer ondemand as "frequency stays at low limit" but experiments with switching to performance governer points to reporting incorrect core.)

Comment 1 Andrew Morton 2009-12-17 00:11:32 UTC

I'll reassign this to cpufreq.

Comment 2 Naga Chumbalkar 2009-12-23 22:01:59 UTC

The problem you reported seems related to the changes below:

[PATCH 0/2] powernow-k8: fix incorrect value reported in cpuinfo_cur_freq:
http://www.spinics.net/lists/cpufreq/msg00766.html

[PATCH 1/2] powernow-k8: read P-state from HW:
http://www.spinics.net/lists/cpufreq/msg00767.html

[PATCH 2/2] powernow-k8: get drv data for correct CPU:
http://www.spinics.net/lists/cpufreq/msg00768.html

These changes went into 2.6.31.

Comment 3 Mark Langsdorf 2010-02-03 19:36:21 UTC

Do the changes that Naga Chumbalkar suggested resolve this issue?

Comment 4 hkmaly 2010-02-04 23:02:42 UTC

Yes, the attached patches resolved the problem. Note that I can't try 2.6.31 because I have ATI card on that machine and must wait until the kernel mode-setting stabilise ...