Messages in this thread | | | Date | Mon, 19 Nov 2007 20:12:36 -0500 | From | Dave Jones <> | Subject | Re: Power Saving |
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On Mon, Nov 19, 2007 at 08:05:29PM -0500, Stephen Clark wrote:
> >I think by throttling, you actually mean changing frequency/voltage ? > >(throttling is something else, where the CPU skips every n cycles, > > which doesn't actually save any power) > > > well what about the info from /proc/ > > cat /proc/acpi/processor/CPU0/info > processor id: 0 > acpi id: 0 > bus mastering control: no > power management: yes > throttling control: yes > limit interface: yes > > and: > cat /proc/acpi/processor/CPU0/throttling > state count: 2 > active state: T0 > states: > *T0: 00% > T1: 50%
See above. These are throttling states, used typically if the system is overheating.
> [root@joker ~]# cat /proc/acpi/processor/CPU0/power > active state: C2 > max_cstate: C8 > bus master activity: d18324c9 > states: > C1: type[C1] promotion[C2] demotion[--] > latency[000] usage[01340140] > *C2: type[C2] promotion[--] demotion[C1] > latency[090] usage[02980043] > > ????
C states are unrelated to frequency/voltage scaling (which are P states) They get taken advantage of automatically by ACPI as you can see from the usage fields.
Dave
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