Messages in this thread | | | Date | Tue, 6 Nov 2018 20:51:27 +0100 | From | Peter Zijlstra <> | Subject | Re: [RFC/RFT][PATCH v3] cpuidle: New timer events oriented governor for tickless systems |
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On Tue, Nov 06, 2018 at 07:19:24PM +0100, Rafael J. Wysocki wrote: > On Tue, Nov 6, 2018 at 6:04 PM Peter Zijlstra <peterz@infradead.org> wrote:
> > Instead of this detector; why haven't you used the code from > > kernel/irq/timings.c ? > > Because it doesn't help much AFAICS. > > Wakeups need not be interrupts in particular
You're alluding to the MWAIT wakeup through the MONITOR address ?
> and interrupt patterns that show up when the CPU is busy may not be > relevant for when it is idle.
I think that is not always true; consider things like the periodic interrupt from frame rendering or audio; if there is nothing more going on in the system than say playing your favourite tune, it gets the 'need more data soon' interrupt from the audio card, wakes up, does a little mp3/flac/ogg/whatever decode to fill up the buffer and goes back to sleep. Same for video playback I assume, the vsync interrupt for buffer flips is fairly predictable.
The interrupt predictor we have in kernel/irq/timings.c should be very accurate in predicting those interrupts.
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