On Tue, 2007-02-06 at 22:09 +0100, Ingo Molnar wrote:
> * Daniel Walker <[email protected]> wrote:
>
> > > it's quite easy to explain: because of the new dynticks feature.
> > > Both 'timer' and 'LOC' counts go way down.
> >
> > I don't have that enabled tho .. This is with HRT/dynamic tick both
> > off..
>
> your kernel utilizes the kernelin a more optimal way: the new
> clockevents code now utilizes the local APIC timer irq (represented by
> the LOC field) for periodic interrupts. The local APIC timer irq has a
> cost of ~2 usecs per IRQ, while the PIT irq is ~10 usecs per irq. With
> HZ=1000 this means savings of ~8000 usecs per second - i.e. 8 msecs per
> second, which is 0.8% more raw CPU power available - which isnt that
> bad.
I'm happy it's better .. I'm not saying it's worse .
> we could make this clearer by renaming 'LOC' (which stands for 'LOCal
> timer interupts' and was added [and misnamed] by yours truly many moons
> ago) to 'apic-timer' and 'timer' to 'PIT-timer' but /that/ would be more
> of a userspace visible change than the change in the counter rates.
If we change the current "timer" entry to be listed as "lapic-timer" and
not "IO-APIC-edge" (or one of the other names) and replace it with the
count from LOC , that would make sense cause that field already changes
depending if you have a io-apic or not ..
I think the regression (if you can call it that) is not scripts
crashing, but more people not know what's going on with there system ..
Daniel
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