[Beowulf] bizarre scaling behavior on a Nehalem

Craig Tierney Craig.Tierney at noaa.gov
Wed Aug 12 14:21:39 EDT 2009


Rahul Nabar wrote:
> On Wed, Aug 12, 2009 at 1:06 PM, Craig Tierney<Craig.Tierney at noaa.gov> wrote:
>> I read there are several different tools to manage the CPU frequency.
>> If you are using Centos/Redhat try:
>>
>> cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_governors
>>
>> Does it list any?  If not, that might be why cpufreq-info can't
>> find anything.
> 
> Thanks again Craig!
> 
> cat: /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_governors:
> No such file or directory
> 
> But I distinctly remember several "power performance " options being
> listed in the BIOS. It is funny that the governors aren't listed. I am
> not sure how I can fix this.
> 
> On my older AMD Barcelonas I am used to setting the governor to
> "performance" and that way it then does not drop its frequency ever.
> 

We have ours set to performance and then copy the setting from scaling_max_freq
to scaling_min_freq to make sure the speed is set right.  When everything works
we will play with modifying that in the prolog/epilog of the batch system to
try and reduce power consumption during idle time.

Craig


-- 
Craig Tierney (craig.tierney at noaa.gov)
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