Userspace: available processorspeeds

Userspace: available processorspeeds

[Jeroen Van der Vegt]

Hello,

I'm trying to write a userspace processor-speed governor for my laptop, 
an Asus L3000D. It has an AMD Athlon Mobile processor and runs on Linux 
2.6.0-test5 (and Debian unstable).

For some reason, my laptop crashes when the speed changes from maximum 
to minimum at once. So my program is to step the speed only to the next 
level available. This is repeated every 5 seconds, so both the maximum 
and minimum speed are reachable.
The available speeds are printed when the module PowerNow is loaded, but 
isn't there a 'better' way to retrieve this information? There doesn't 
seem to be a file listing all possible speeds in either /proc nor /sys. 
Have I overlooked a file perhaps, or is there some function call I can use?

Besides this, I have experienced the following weirdness: according to 
/sys/.../scaling_min_freq, my processor's minimum speed is 532 Mhz. I 
have, however, had it running at 292Mhz (as reported by /proc/cpuinfo). 
It's not really reproducible unfortunately, and I only noticed it once 
or twice.The laptops keeps working fine though, so it's not much of a 
problem to that respect. Any actions I should take the next time I see it?


Regards,

Jeroen van der Vegt.

Re: Userspace: available processorspeeds

[Ducrot Bruno]

On Mon, Oct 06, 2003 at 11:19:25AM +0200, Jeroen Van der Vegt wrote:
> Hello,
> 
> I'm trying to write a userspace processor-speed governor for my laptop, 
> an Asus L3000D. It has an AMD Athlon Mobile processor and runs on Linux 
> 2.6.0-test5 (and Debian unstable).
> 
> For some reason, my laptop crashes when the speed changes from maximum 
> to minimum at once. So my program is to step the speed only to the next 
> level available. This is repeated every 5 seconds, so both the maximum 
> and minimum speed are reachable.

Please be sure to upgrade to linux-2.6.0-test6 at least, due to some bugs
in previous versions in powernow-k7.

> The available speeds are printed when the module PowerNow is loaded, but 
> isn't there a 'better' way to retrieve this information? There doesn't 
> seem to be a file listing all possible speeds in either /proc nor /sys. 
> Have I overlooked a file perhaps, or is there some function call I can use?
> 
> Besides this, I have experienced the following weirdness: according to 
> /sys/.../scaling_min_freq, my processor's minimum speed is 532 Mhz. I 
> have, however, had it running at 292Mhz (as reported by /proc/cpuinfo). 

Strange.  Perhaps a bug somewhere in core?

> It's not really reproducible unfortunately, and I only noticed it once 
> or twice.The laptops keeps working fine though, so it's not much of a 
> problem to that respect. Any actions I should take the next time I see it?

Look what say bogomips, or x86info --mhz

Cheers,

-- 
Ducrot Bruno

--  Which is worse:  ignorance or apathy?
--  Don't know.  Don't care.

Re: Userspace: available processorspeeds

[Dave Jones]

On Mon, Oct 06, 2003 at 11:19:25AM +0200, Jeroen Van der Vegt wrote:

 > Besides this, I have experienced the following weirdness: according to 
 > /sys/.../scaling_min_freq, my processor's minimum speed is 532 Mhz. I 
 > have, however, had it running at 292Mhz (as reported by /proc/cpuinfo). 

The 532 is a calculated speed using FSB speed * a multipler.
The 292 is an estimate based upon bogomips calculation at boot time,
and also, is subject to thermal throttling by ACPI if present.

Think of '532' as actual speed, and '292' as effective speed.

		Dave

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