Re: Available speed governors for Athlon64

From: General Schvantzkoph (schvantzkoph_at_yahoo.com)
Date: 02/21/05


Date: Mon, 21 Feb 2005 15:32:16 -0500

On Mon, 21 Feb 2005 20:01:32 +0000, Wes Newell wrote:

> On Mon, 21 Feb 2005 10:53:07 -0500, General Schvantzkoph wrote:
>
>> I have an Athlon 64 3800+/Nforce 3-250Ultra system running Fedora Core 3
>> with a custom 2.6.9 kernel. In the kernel configuration the performance,
>> userspace, powersave and ondemand performance governors have all been
>> selected however the
>> /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_governors file
>> lists only performance and userspace. I've tried to add powersave and
>> ondemand to the file but it reverts to just userspace performance. How do
>> I get the kernel to support powersave and ondemand. Ondemand seems like a
>> particularly useful power governor.
>
> BTW, I don't know what ondemand is. It's not a valid governor here, but
> I'm running a 2.6.8 kernel. maybe it's a new one. But powersave is
> probably a module that needs to beloaded. It is here. Perhaps ondemand is
> also. I don't know what ondemand would give you that userspace doesn't
> unless it lets you set speeds and/or voltages other than the default. That
> would be nice.

ondemand is in the 2.6.9 kernel, might be new there. Here is it's
definition from the kernel,

'ondemand' - This driver adds a dynamic cpufreq policy governor. The
governor does a periodic polling and changes frequency based on the CPU
utilization. The support for this governor depends on CPU capability to do
fast frequency switching (i.e, very low latency frequency transitions).

Assume that it's reliable this is the governor that you would want to use.
It allows the CPU to run cooler when it's not under load while still
delivering the maximum performance when it's needed.