[CentOS] Questions on cpu frequency scaling AMD vs. Intel

Mon Aug 4 01:47:06 UTC 2008
S.Tindall <tindall.satwth at brandxmail.com>

On Sunday, August 03, 2008 at 8:31 AM, Kai Schaetzl wrote:
> ...I have an older low-voltage AMD CPU (probably about 2 years
> on the market) that is recognized as X2 3800+ but frequency
> scaling fails because it miscalculates the current speed to
> 800 MHz as well. Is there anything I can do about that? Where
> could I check whether this CPU should be supported in full and
> frequency scaling working?

The cpuspeed changelog may be relevant:

* Thu Mar 06 2008 Jarod Wilson <jwilson at redhat.com>

- Disable freq scaling by default on AMD rev F and earlier cpus
when running xen, due to clock instability (#435321)

I didn't look up your cpu, but I think it's a revision F.

Also, thanks for the /etc/sysconfig/cpuspeed "ondemand" tip.

It seemed counterintuitive to explicitly specify the so-called
default governor value (i.e., "empty defaults to ondemand"),
but doing so did the trick under xen for my
revision G AMD processor.