Re: [Math-atlas-devel] CPU throttling

[dean g. <de...@ar...>]

On Wed, 31 May 2006, Clint Whaley wrote:

> Guys,
> 
> Thanks for the pointers.  One thing that would be handy is having config
> detect if CPU throttling is enabled, and issue a warning with the opportunity
> to crap out if it's detected.  Does anyone know how to do this generally on
> the following OSes:
>    Linux
>    *BSD
>    Windows (yeah, right)
>    any other OS you care to name?
> 
> Under Linux, sounds like there are multiple ways to throttle, do they have
> to be detected individually, or is there something we can always probe?

on linux the cpufreq infrastructure is supposed to unify everything ... 
and the sysfs interface to cpufreq is the One True Way... i believe there 
are some other legacy methods, but if you detected/handled 
/sys/devices/system/cpu*/cpufreq/ you'd get probably 95%+ coverage.

you could have your makefile detect if scaling_frequency_min < 
scaling_frequency_max and if running as root offer to set min == max, 
otherwise paste the shell commands the user could run as root in another 
window to deal with it...

can't help you with the rest :)  windows has an API but it's nowhere near 
as easy to manipulate from shell tools.

-dean