[Linux-sony] altering processor speed when running on battery

[Clifford T. Matthews]

>>>>> "Bryan" == Bryan Lawrence <b.n.lawrence@rl.ac.uk> writes:

    Bryan> Hi Folks I'm running suse8.1 with a 2.4.20 kernel with acpi
    Bryan> (and swsusp, not that it works ...but I'm waiting til
    Bryan> someone else solves that) on a R600 HMPD.

    Bryan> It would appear that I ought to be able to drop the
    Bryan> processor speed down when I'm running on battery, however,
    Bryan> i can't find any info on how to do that ...

I've used acpi From December 12th 2002.

Try looking in /proc/acpi/processor/CPU0/

ctm@canceled ctm]$ cat /proc/acpi/processor/CPU0/performance
state count:             2
active state:            P0
states:
   *P0:                  1800 MHz, 30000 mW, 250 uS
    P1:                  1200 MHz, 20200 mW, 250 uS


To switch from P0 to P1 you just write "1" to performance:

[root@canceled ctm]# echo 1 > /proc/acpi/processor/CPU0/performance
[root@canceled ctm]# cat /proc/acpi/processor/CPU0/performance
state count:             2
active state:            P1
states:
    P0:                  1800 MHz, 30000 mW, 250 uS
   *P1:                  1200 MHz, 20200 mW, 250 uS

[root@canceled ctm]# cat /proc/acpi/processor/CPU0/throttling
state count:             8
active state:            T0
states:
   *T0:                  00%
    T1:                  12%
    T2:                  25%
    T3:                  37%
    T4:                  50%
    T5:                  62%
    T6:                  75%
    T7:                  87%

[root@canceled ctm]# echo 7 > /proc/acpi/processor/CPU0/throttling
[root@canceled ctm]# cat /proc/acpi/processor/CPU0/throttling
state count:             8
active state:            T7
states:
    T0:                  00%
    T1:                  12%
    T2:                  25%
    T3:                  37%
    T4:                  50%
    T5:                  62%
    T6:                  75%
   *T7:                  87%

I hope the above helps.  I see there's a new acpi patch on
sourceforge.  I haven't played with it yet.

--Cliff			After their escape, purchases of
ctm@ardi.com		lightweight fabrics were limited