5-STABLE cpufreq hotter than est from ports

[Nate Lawson]

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%.

A variant of your patch has been committed and will be MFCd.  Thanks!

> So, I've worked out a patch (attached) that makes sure
> that a lower frequency level has at most the same absolute setting
> (preferably less of course). This eliminates quite a few levels so
> somebody with a better knowledge of cpufreq should check if this patch
> really does something good. This is the first time I've taken a look at
> FreeBSD source code by the way.

I added back the check for CPUFREQ_CMP since you don't want duplicate 
levels.  This is not currently a problem with est/p4tcc but other 
combinations of settings could have produced duplicates with the patch's 
approach.

> Also, somewhat related, the p4tcc driver doesn't recognise
> acpi_throttle, which means that when you load the cpufreq module after
> booting, the freq levels are messed up. I'm not sure what the best
> solution for this is. Let p4tcc detect acpi_throttle and don't attach
> if it's present (like acpi_throttle does now if it finds p4tcc) or
> detach it before attaching? Or maybe p4tcc and acpi_throttle should be
> merged into one driver?

acpi_throttle is only the same as p4tcc on x86 platforms.  We need a 
better negotiation strategy in general between the different drivers. 
The logic for these two is already p4tcc > acpi_throttle but we need to 
support reprobing when cpufreq.ko is loaded after boot by detaching both 
and then allowing p4tcc to win the probe.

-- 
Nate