5-STABLE cpufreq hotter than est from ports

[Kevin Oberman]

> Date: Tue, 9 Aug 2005 11:35:29 +0200
> From: Bruno Ducrot <ducrot at poupinou.org>
> Sender: owner-freebsd-stable at freebsd.org
> 
> On Tue, Aug 02, 2005 at 12:22:02AM +0200, Tijl Coosemans wrote:
> > A couple days ago I updated my system and was excited to see cpufreq
> > and powerd in 5-stable. Since then however I noticed that my laptop
> > temperature is about 5°C higher than with est and estctrl. I found that
> > cpufreq when setting 200MHz for example set the absolute frequency to
> > 1600MHz (max for this laptop) and the relative frequency (p4tcc) to
> > 12.5% instead of using a more power conserving setting like 800MHz/25%.
> > 
> > The problem is that cpufreq_expand_set() (sys/kern/kern_cpu.c)
> > traverses freq levels from high to low when adding relative levels and
> > skips duplicates. When it wants to add 800MHz/25% it sees this setting
> > as a duplicate of 1600MHz/12.5% it has found before. This can be fixed
> > by letting cpufreq_expand_set() traverse freq levels in reverse order
> > (and still skipping duplicates). Then each frequency level has the
> > lowest possible absolute setting. This is a one line change in
> > sys/kern/kern_cpu.c (line 653).
> 
> It's a well known bug.  Someday I think I will have enough time to fix
> that one if Nate don't bite me.

I have been running with Tijl's patch set for several days with great
results. Testing has shown that the patches resolve both issues and I
now see only 11 CPU speeds, all of those below the lower CPU clock speed
are at that lower speed. Thus far I have seen no negative issues. The
temperature of my system is noticeably cooler when not running something
that is compute intensive.
-- 
R. Kevin Oberman, Network Engineer
Energy Sciences Network (ESnet)
Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab)
E-mail: oberman at es.net			Phone: +1 510 486-8634