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axel668

Member

Registered: 2009-08-15

Posts: 168

Atom D / Asus 1215N cpufreq ondemand governor

Hi !

Has anyone succeeded in running an Intel Atom D525 or similar (the critical point being the "D") with the ondemand governor ?

I have cpufreq installed according to http://bbs.archbang.org/viewtopic.php?pid=9153#p9153, but using the p4_clockmod driver (none of the others seems to be suppirted for Atom D, see https://wiki.archlinux.org/index.php/Cp … cy_driver).

Now I am able to run with the cpufreq_powersave governor (minimum frequency) or cpufreq_performance (maximum frequency) or to set a specific frequency with cpufreq-set -f, but none of the dynamic governors (ondemand, conservative) seem to work. I can load them with modprobe and they are shown as available in cpufreq-info, but I don't get them applied (cpufreq-info keeps showing "performance" or "powersave" as active, depending on what went wrong before).

Anybody using an Atom D CPU, and knowing how to overcome this problem ? Was already thinking about writing a python script that polls cpu load and then sets the frequency accodingly, but I'm, not sure if this really makes sense.

Thanks, Axel

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"A computer lets you make more mistakes faster than any invention in human history - with the possible exceptions of handguns and tequila."
(Mitch Ratcliffe)

lagagnon

Member

From: an Island in the Pacific...

Registered: 2009-12-10

Posts: 1,087

Website

Re: Atom D / Asus 1215N cpufreq ondemand governor

AFAIK many Atom processors can't be frequency set. As they are such low power devices anyways it hardly would make any difference from what I understand of the actual datasheets...

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Philosophy is looking for a black cat in a dark room. Metaphysics is looking for a black cat in a dark room that isn't there. Religion is looking for a black cat in a dark room that isn't there and shouting "I found it!". Science is looking for a black cat in a dark room with a flashlight.

Gusar

Member

Registered: 2009-08-25

Posts: 3,607

Re: Atom D / Asus 1215N cpufreq ondemand governor

@lagagnon: It's actually the other way around - most Atoms *can* do freq scaling, this is the first time I hear of one that can't. Atom is not that low power that it wouldn't make a difference. Heck, even the *really* low power ARM processors in cellphones do freq scaling.

@axel668: p4_clockmod doesn't do freq scaling. How could it, when it's a module for clock modulation on p4 processors, as it says right there in the name. It's purpose is thermal management, not power saving. When you load the powersave governor, the freq of the processor doesn't actually change, it's still at maximum. It's just that the processor doesn't do work every tick. That's what clock modulation is. So using a scaling governor doesn't make sense.

I'll do a bit of a search about the Atom D525. Edit: It seems the D series really doesn't have freq scaling. But it's the only one, other series of Atoms do have it. So just forget about any governors and such. Not applicable to this processor. Just load the p4_clockmod module, it'll kick in should the cpu temp go really high, to prevent overheating.

Last edited by Gusar (2012-05-15 20:20:03)

axel668

Member

Registered: 2009-08-15

Posts: 168

Re: Atom D / Asus 1215N cpufreq ondemand governor

ok thanks, this is what I feared already

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"A computer lets you make more mistakes faster than any invention in human history - with the possible exceptions of handguns and tequila."
(Mitch Ratcliffe)