PowerTOP for FreeBSD ?
Nate Lawson
nate at root.org
Thu May 17 17:59:26 UTC 2007
Peter Jeremy wrote:
> On 2007-May-16 00:00:46 -0700, Nate Lawson <nate at root.org> wrote:
>> Normally timers tick every 1 us on FreeBSD.
>
> Unless something has changed massively, tradtiionally, hardclock
> interrupts every 1msec and statclick interrupts at 128Hz (approx
> 8msec).
>
Oops, yes it's every 1 ms (1/1000 sec). I didn't bother mentioning stat
clock since it's derived from hardclock and that's the only one that
makes the CPU exit its idle state.
>> Most interrupts are
>> serviced with no work to be performed, so it's just wasted computation.
>
> Using the lapic timer is an excellent example of this. By default it
> runs at 2000Hz to run hardclock() every 1msec and statclock() every
> 7.5 msec - just under 50% of the interrupts are completely wasted.
>
Absolutely.
--
Nate
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