about cpufreq on intel dual core processor

about cpufreq on intel dual core processor

[M C]

Hi, I have a simple question about cpufreq on intel dualcore processor.

if each core has six frequency levels, then should i change the frequency levels for both of the cores simultaneously or i can change them separately?

because the processor supports hyper threading techonogy, so there are fours cores in the linux system. then how should i treat the four cpu when i want to do the frequency scaling?

Thanks.

Ming




       
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Re: about cpufreq on intel dual core processor

[Dave Jones]

On Sat, Aug 18, 2007 at 07:54:01AM -0700, M C wrote:
 > Hi, I have a simple question about cpufreq on intel dualcore processor.
 > 
 > if each core has six frequency levels, then should i change the frequency levels for both of the cores simultaneously or i can change them separately?
 > 
 > because the processor supports hyper threading techonogy, so there are fours cores in the linux system. then how should i treat the four cpu when i want to do the frequency scaling?

You are able to set different frequencies per core, however you only
save power per-socket, so unless they're all ramped down, you won't
be lowering the voltage of the socket if one core keeps the package busy.

	Dave

-- 
http://www.codemonkey.org.uk

Re: about cpufreq on intel dual core processor

[Arjan van de Ven]

On Wed, 22 Aug 2007 20:18:15 -0400
Dave Jones <davej@redhat.com> wrote:

> On Sat, Aug 18, 2007 at 07:54:01AM -0700, M C wrote:
>  > Hi, I have a simple question about cpufreq on intel dualcore
>  > processor.
>  > 
>  > if each core has six frequency levels, then should i change the
>  > frequency levels for both of the cores simultaneously or i can
>  > change them separately?
>  > 
>  > because the processor supports hyper threading techonogy, so there
>  > are fours cores in the linux system. then how should i treat the
>  > four cpu when i want to do the frequency scaling?
> 
> You are able to set different frequencies per core, however you only
> save power per-socket, so unless they're all ramped down, you won't
> be lowering the voltage of the socket if one core keeps the package
> busy.

and in fact, both your cores will run at the same frequency (the
maximum of the ones you set) anyway... they will NOT run at separate
frequencies.