5-STABLE cpufreq hotter than est from ports

[Nate Lawson]

Kevin Oberman wrote:
>>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.

I'm working on reviewing and perhaps rewriting some of the patches. 
They may work fine but there are some subtle issues, for instance, with 
future systems that support more than one relative driver.  The goals 
are correct but the implementation needs a little work.

-- 
Nate