On Wed, Jul 08, 2009 at 12:16:58PM +1000, Trent W. Buck wrote:

Hi Trent.

> After upgrading from .29 to .30, I can no longer change my CPU
> frequency scaling governor:
> 
>     # cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_governors
>     ondemand performance
>     # printf ondemand >/sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
>     # cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
>     performance
> 
> This is super annoying.  I am using an EeePC 701 with a Celeron CPU.
> 
> ** Kernel log:
> [   73.276680] ondemand governor failed, too long transition latency of HW, 
> fallback to performance governor
> [  158.079576] ondemand governor failed, too long transition latency of HW, 
> fallback to performance governor
> [ 2192.786164] ondemand governor failed, too long transition latency of HW, 
> fallback to performance governor
> [ 2235.556866] ondemand governor failed, too long transition latency of HW, 
> fallback to performance governor
> 
> ** Loaded modules:
> Module                  Size  Used by
> p4_clockmod             3948  0 
> speedstep_lib           4136  1 p4_clockmod

I'm also hit by this bug. I've found some information at
<http://bugs.archlinux.org/task/15284>:
| You should not use ondemand with clockmod. The clockmod module has
| a very high switching latency, that's why it's disabled in 2.6.30. The
| error message says it all I think.

Unfortunately p4-clockmod is the only driver working with my CPU
(Intel(R) Celeron(R) CPU 2.60GHz), but You have newer CPU, so maybe it's
worth trying other drivers.

Of course I see it as a regression, it would be nice, if it gets
fixed...

Jarek.

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