Powersaving with Xeon CPU (cpufreq)?

[mad]

Hi!

I'm wondering if CPU frequency sclaing works with a Xeon E3-1220Lv2.
With all my other Debian installations frequency scaling works out of
the box (not even cpufrequtils is installed), but not with the E3. Or
does this CPU not "scale" and it has some other power saving methods?
Web searches were not very informative and cpufreq-info only says:

# cpufreq-info
cpufrequtils 008: cpufreq-info (C) Dominik Brodowski 2004-2009
Report errors and bugs to ***@vger.kernel.org, please.
analyzing CPU 0:
no or unknown cpufreq driver is active on this CPU
maximum transition latency: 4294.55 ms.
analyzing CPU 1:
no or unknown cpufreq driver is active on this CPU
maximum transition latency: 4294.55 ms.
analyzing CPU 2:
no or unknown cpufreq driver is active on this CPU
maximum transition latency: 4294.55 ms.
analyzing CPU 3:
no or unknown cpufreq driver is active on this CPU
maximum transition latency: 4294.55 ms.

I can load certain modules (speedstep-lib) and governors, but it still
doesn't work. I know from Scientific Linux that a (different) Xeon CPU
can scale. I also tried kernel 3.2 and 3.16.

Anyone already has experience with this CPU?

TIA
mad

[Henrique de Moraes Holschuh]

Post by mad
I'm wondering if CPU frequency sclaing works with a Xeon E3-1220Lv2.

Yes. But AFAIK the cpufreq backend kernel driver for that platform depends
on the motherboard's ACPI information to work.

i.e. make sure your UEFI/BIOS is up-to-date, and properly configured (it can
have configurable performance modes that limit the range of cpufreq...).

Post by mad
does this CPU not "scale" and it has some other power saving methods?

It has other power saving methods, indeed. They're called "idle states",
and they are managed either through acpi-idle (ACPI C-states) or directly
("intel-idle" driver).

How well either will work depends on the quality of your UEFI/BIOS, and in
the case of intel-idle, kernel version.
--
"One disk to rule them all, One disk to find them. One disk to bring
them all and in the darkness grind them. In the Land of Redmond
where the shadows lie." -- The Silicon Valley Tarot
Henrique Holschuh