powerd effectiveness

[Bruno Ducrot]

Hi Make,

On Thu, Jan 12, 2006 at 01:11:52AM -0500, Mike Jakubik wrote:
> Daniel O'Connor wrote:
> >Wow, that's weird, wish my AMD would do speeds like that :)
> >
> >As for your temperature observation - I have no idea sorry. It would 
> >appear that powerd is doing the right thing but for some reason your CPU 
> >is not benefiting. That said checking by measuring temperature is fraught 
> >with complexity because there is probably a significant delay between a 
> >change in power consumption and a corresponding chaange in heatsink 
> >temperature.
> >  
> 
> Actually, i took readings from the wrong box :P
> 
> CPU: AMD Athlon(tm) Processor (1210.79-MHz 686-class CPU)
> acpi0: <ASUS A7V> on motherboard
> 
> root at mail:~# sysctl dev.cpu.
> dev.cpu.0.%desc: ACPI CPU
> dev.cpu.0.%driver: cpu
> dev.cpu.0.%location: handle=\_PR_.CPU0
> dev.cpu.0.%pnpinfo: _HID=none _UID=0
> dev.cpu.0.%parent: acpi0
> dev.cpu.0.freq: 75
> dev.cpu.0.freq_levels: 1215/-1 1139/-1 1063/-1 987/-1 911/-1 835/-1 
> 759/-1 683/-1 607/-1 531/-1 455/-1 379/-1 303/-1 227/-1 151/-1 75/-1
> 
> Thats the correct one, it is 75mhz. I was suspecting hardwares 
> limitations in terms of modulating the frequency quickly enough. Just 
> wanted to make sure.

What you have noticed is acpi_throttle(4).  The combinaison of
some VIA chipset and AMD processors give 16 frequencies.
powerd(8) is not designed for thermal stuff, and will never be.
It's up to acpi_thermal(4) to cool the processor if needed.

Note that I think acpi_throttle(4) can only be used for cooling a processor.
I don't think it is usefull for power comsuption at all for which
powerd(4) is designed.  Some other people may have different opinion of
course.

BTW you may want to try to check if setting hw.acpi.cpu.cx_lowest to C2
permit to cool the processor.  There are a lot of old systems based upon
AMD processors that require this for resolving overheating issues.

You may also want to check if sysutlis/fvcool can help you if setting
the above sysctl is not possible (but don't mix the two).

Cheers,

-- 
Bruno Ducrot

--  Which is worse:  ignorance or apathy?
--  Don't know.  Don't care.