How/why would dev.cpu.0.freq_levels change??!?

David Wolfskill david at catwhisker.org
Sun Jun 29 02:16:31 UTC 2008


On Sat, Jun 28, 2008 at 05:32:16PM -0700, Kevin Oberman wrote:
> > From: John Baldwin <jhb at freebsd.org>
> > ...
> > Looks like it lowered the temperature.  Your BIOS might have decided to change 
> > the levels to force the CPU to throttle down to cool the system.

I suppose.  :-(  But as I noted, it often runs for extended periods at
around 85C, so the rationale (if any) for such a maneuver escapes me.

> Any chance you moved to battery at any time? My ThinkPad BIOS drops my
> CPU's top speed from 2G to 800M when I go onto battery.

In this case, I definitely did not, and I was on AC at the time I
reported the issue.  I've noted recurrences since -- one of which was
particularly ntable because dev.cpu.0.freq_levels reported that the
fastest available spedd was 1200 MHz, while dev.cpu.0.freq reported that
the machine was running at 2400 MHz.

Through some experimentation, it appears that I can reduce the
probability of the event -- and possibly avoid it altogether (I can't be
sure yet) by killing off powerd.  (I apologize for failing to mention
that I run it, using default settings.)

Also, I've only seen it while running RELENG_6 -- not RELENG_7 or HEAD.
Then again, I generally only run RELENG_7 or HEAD enough to build them.

Thanks for the responses so far.

Peace,
david
-- 
David H. Wolfskill				david at catwhisker.org
I submit that "conspiracy" would be an appropriate collective noun for cats.

See http://www.catwhisker.org/~david/publickey.gpg for my public key.
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