On 5/2/06, Ken Moffat <[EMAIL PROTECTED]> wrote:
On Tue, May 02, 2006 at 12:28:35PM +0000, Warren Wilder wrote:
> I have a question about scaling the frequency of the cpu clock cycle.
>
> This isn't in the book, but I can't find much info on it otherwise.
>
*cough* I did write a hint about it, but only based on systems I
own, so it doesn't cover your detailed questions.
> It is/should be possible to set the cpu frequency governor in userspace.
> This can be done with the cpufrequtils package from:
> http://www.kernel.org/pub/linux/utils/kernel/cpufreq/cpufrequtils.html
> together with the daemon from:
> http://cpufreqd.sourceforge.net/
Why do you think you need those (I'm curious) ? On my ppcs I *do* need
a daemon, and I use powernowd. On my athlon64s I just use ondemand
in the kernel and it works nicely on the boxes where the bios
supports it. The ppcs need a daemon because of something to do with
latency in frequency changes. I don't see what utils could possibly
be needed - if it works, set up an init script to allow you to
select as-needed/low-speed/full-speed for the rare occasions when
as-needed speed changing is not appropriate.
> Now, about my question.
> I have a Via SP13000 mini-itx system with a processor that at maximum
> can reach 1.3GHz.
> However, in this file (the maximum allowed frequency for a governor):
> /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq
> it reads 2 GHz.
> The minimum allowed frequency in:
> /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_min_freq
> reads 800 MHz.
>
> The maximum value is obviously not correct for my system. I wonder
> whether there is actually something wrong, or whether I should simply
> use the cpufrequtils to set a maximum and minimum value by hand at every
> boot. I also wonder what kind of value is sane as a minimum.
>
> Right now, cpufreqd doesn't seem willing to let go of the "Performance
> High" profile. This is probably because of the 2 Ghz value.
>
I remember seeing a posting on lkml from Dave Jones talking about
disabling cpufreq scaling on some/all vias, because it was so
broken. Probably, you need to ask on the cpufreq list (I think the
address is in the kernel docs, it's a subscription list as I found
out when CC'ing them about something a while ago).
Ken
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I have a amd64 with the powernow stuffs and i can use the kernel
controlled ones as ken pointed out but the userspace control failes to
showup in /sys for some reason. This might be why its not working.
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