Messages in this thread | | | Date | Thu, 29 Jan 2009 08:32:41 -0800 (PST) | From | Xiaoning Ding <> | Subject | Re: a question about p4_clockmod module on Xeon quad core processors |
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--- On Thu, 1/29/09, Dave Jones <davej@redhat.com> wrote:
> From: Dave Jones <davej@redhat.com> > Subject: Re: a question about p4_clockmod module on Xeon quad core processors > To: "Xiaoning Ding" <dingxn@ymail.com> > Cc: linux-kernel@vger.kernel.org > Date: Thursday, January 29, 2009, 2:45 AM > [please don't top-post] > > On Wed, Jan 28, 2009 at 06:06:37PM -0800, Xiaoning Ding > wrote: > > > > > I have tried the p4-clockmod module in > Linux kernel > > > 2.6.29 on Xeon 5355 quad-core CPUs with no luck. > It seems > > > current p4-clockmod driver still cannot support > Intel Quad > > > core processors, right? > > > > > > > > I know I can also use acpi-cpufreq. It can > only scale > > > down the frequence from 2.67GHz to 2GHz. But I > need some > > > lower frequencies for some experiments. > > > > > > p4-clockmod doesn't change the processor > frequency. > > > Because of common misconceptions like this, the > user > > > interface has been removed. > > > > > > In 2.6.29, the clock modulation code is called > directly > > > from ACPI > > > whenever thermal events indicate that throttling > is > > > necessary. > > > > > Thanks for the correction. > > My experiments need to reduce CPU speed. However, I > can only reduce the speed by about 30% (from 2.67GHz to > 2GHz) with ACPI. That is not enough for the experiments. > > The ACPI P-states are nearly always correct, so you > won't be > able to go below 2GHz on this system.
That's true for changing P-States with ACPI. But I can still get slower speed with clock modulation, right? > > p4-clockmod has not been removed from 2.6.29. It is > under the same directory as acpi-cpufreq > (arch/x86/kernel/cpu/cpufreq). So I thought it was an > alternative approach. But I could not get it loaded. > > The driver is present, the _user interface_ has been > removed.
The module cannot loaded on Xeon 5355. If I can load it, I hope I can find a method to use it.
> Dave > > -- > http://www.codemonkey.org.uk > -- > To unsubscribe from this list: send the line > "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at > http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/
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