5-STABLE cpufreq hotter than est from ports

[Nate Lawson]

Tijl Coosemans wrote:
> Kevin,
> 
> Thanks for your reply. I was beginning to think I sent my mail to the 
> wrong list. I've subscribed to freebsd-acpi@ now. For reference, the 
> issues (+patch) discussed are available at:
> 
> http://lists.freebsd.org/pipermail/freebsd-stable/2005-August/017535.html
> http://lists.freebsd.org/pipermail/freebsd-stable/2005-August/017536.html
> 
> 
>>I have a P4m with ICHSS and P4TCC and I do hit both the problem of the
>>wrong mode being selected when there is a tie for performance level
>>and the case of lower performance resulting in higher power
>>consumption. You can see the results of my testing in messages to
>>freebsd-acpi@ archives. I have been wanting to write some patches to
>>fix the problems, but have simply not had time, so these patches look
>>great! 
> 
> 
> In my experience throttling doesn't really gain that much. There's 
> almost no difference between running at 600MHz/100% and 600MHz/12.5%, 
> except that it is 8 times slower, so I've set debug.cpufreq.lowest to 
> 400 to limit the performance drop.

It should produce a linear savings in power but other factors may affect 
it.  Think about a server that gets a 1 minute burst every hour.  You 
definitely want to use all the power saving you can, including 
throttling, to get the most out of the other 59 minutes.

> I've also slightly modified powerd to not jump to the maximum frequency, 
> but to step up one level at a time to save energy. I've been thinking, 
> since throttling doesn't gain much, it might be better for powerd to 
> use only absolute settings when stepping up, but that would require an 
> extra sysctl entry (dev.cpu.0.freq_abs or something).

That has been committed also (via phk).

> I've found references in the following files. There may be more of 
> course.
> 
> sys/conf/files.i386 (line 258)
> sys/conf/options.i386 (line 56)
> sys/i386/conf/NOTES (line 133 + line 215).
> sys/i386/i386/p4tcc.c (can be removed?)

I just took care of this too since I had a moment.

-- 
Nate