Le vendredi 05 fivrier 2010 20:07:51, Schvberle Daniel a icrit :
quoted text
> > From: Jean-Francois [mailto:jfsimon1981@gmail.com]
> > Sent: Friday, February 05, 2010 5:46 PM
> >
> > Le vendredi 05 fivrier 2010 17:43:30, vous avez icrit :
> > > > Hello,
> > > >
> > > > I think of doing this too.
> > > > What I would like to understand is if I will be able to use the
> >
> > frequency
> >
> > > > change 1000 / 2000 MHz dynamic load based.
> > > >
> > > > Regards
> > >
> > > Do you mean change the frequency depending on load on the computer...?
> > > This is very easy in a virtual environment, I am not sure on machine. I
> > > have seen windows software that allows you to change certain options
> > > while in the OS, though weather you could do this in OpenBSD and
> > > dynamically you will need to see if someone else knows the answer.
> > > GPU's are very easy to do this with...certainly doing it manually, but
> > > CPU stuff I'm not so sure...
> >
> > Ok.
> > I was thinking this is integrated in the core of AMD processor.
> > Anyway I will see depending on the sunked power if it is necessary to
> > reduce
> > it further.
> >
> > Yes, usually the AMD proc use auto reduce of the frequency during
> > standstill
> > of the OS.
>
> The CPU has the ability to lower it's speed but it's the OS that tells it
> when to slow down. That's what apm -C tries to do.
>
> I'm using this at home to reduce power $$$. I've reduced the CPU voltage,
> and the speed of the integrated GPU (since it's running headless anyway),
> put all HDDs on idle timers (IBM/Hitachi drives have some nice powersaving
> features) and my multi-TB storage is usually consuming below 100W intake.
> Also, apm -C is pure pleasure and gives a significant reduction with my
>  setup.
>
> Note: When running with the lowest multiplier, HDD I/O performance may
>  suffer. In my case the lowest CPU rate is at 1000MHz and with full I/O
>  load accross 1 or 2 HDDs the CPU load is below the treshold of the apm -C,
>  so it doesn't speed up. If I switch it manually with apm -H the transfer
>  rate doubles. No RAID here so we're speaking about 30MB/s with apm -C vs.
>  60MB/s for apm -H. Forgot to mention but this is for stuff served over
>  samba meaning there is some network I/O involved also.
>
>
> Regards, Daniel.

Hi,
Re your answer, from man page APM(8) :

     -C      Set apmd(8) to cool running performance adjustment mode.  In
this
             mode, when CPU idle time falls below 10%, apm raises hw.setperf
             as much as necessary.  Otherwise when CPU idle time is above
30%,
             apm lowers hw.setperf as much as possible to reduce heat, noise,
             and power consumption.

     -H      Set apmd(8) to manual performance adjustment mode and hw.setperf
             to 100.

I don't understant why you have lower performances after "apm -C" while in my
opinion it should just adjust low / fast in function of the system load
requirement ? Are disk IO not consideredas CPU load ?

Regards.