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Re: CPU Frequencies Don't scale independently



Volkan YAZICI wrote:
Hi,

On Sun, 29 Jun 2008, Hakan BAYINDIR <hakan@bayindir.org> writes:
  
I'm running debian testing on a Intel Core2Quad Q6600 CPU with 4
gigabytes of RAM for 7 months. Until 2.6.22, the kernel was scaling each
of my cores independently of each other but starting with 2.6.22, every
core is running in the same frequency. While this doesn't pose any
stability or performance issues, causes higher temprature and noise when
I run a single threaded computing intensive job.

I tracked the cause a bit. I was able to dig upto
"/sys/devices/system/cpu/cpuX/cpufreq/affected_cpus". This file says
which CPUs should scale together. Since file is read only even to root I
think it's an unconfigurable option. I also found that cpu frequencies
are adjusted by cpufreq_acpi module and I cannot find any configuration
related to it files in my system (with my current knowledge).

The weird thing is I'm running an exact clone of this system in my
office with a core2duo system which scales its cores independently. I
cloned my home system to the office when I was running an Athlon64,
approximately 1.5 years ago.

If anybody can say what is wrong, is it the expected behavior, where
should I look further, or whom I can talk to?

BTW, I'm running 2.6.24-1-686-bigmem kernel prepackaged from debian testing.
    
Did you solve your problem? I may recommend you to read files under
linux/Documentation/cpu-freq directory. BTW, sending your
/proc/config.gz might be helpful.


Regards.

  
Hi,

I was unable to solve my problem so, I got the source of the kernel I'm using from Debian with apt-source. The cpu_freq dcoumentation doesn't show affected_cpus in the interface so it's unconfigurable as I guessed. So I found cpu-freq mailing list from the docs and I think I'll continue digging from there.

But first, I'll try with an ubuntu live CD to verify behavior.

Cheers and Regards,

--Hakan.

P.S. I cannot send a config.gz since the kernel is prepackaged.

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