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    SubjectRe: Power Saving
    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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