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SubjectRE: [patch] prefer TSC over PM Timer
dean gaudet writes:
> On Tue, 16 Nov 2004, Pallipadi, Venkatesh wrote:
>
> > I think trying to remove repeated inl()'s in read_pmtmr is a better
> > fix for this issue. As John mentioned in other thread, we should do
> > repeated reads only when something looks broken. Not always.
>
> that would be a nice improvement... then timer_pm will only be 3x as slow
> as timer_tsc instead of 10x slower :) it's still a lot of unnecessary
> overhead for many systems, and unfortunately this is a real performance
> problem (albeit exaggerated by code which is overzealous in its use of
> gettimeofday()).
>
> on a tangent... has the local apic timer ever been considered? it's fixed
> rate, and my measurements show it in the same performance ballpark as TSC.
>
> i know that all p3, p-m, p4, k8 and efficeon have local APIC, but i'm not
> sure if k7 (other than k7 smp parts of course) have local apics... so i'm
> not sure how widespread it is compared to pm-timer.

All K7/K8s except the very first K7 Model 1 have local APICs.
There is no difference between UP and MP parts in this respect.

/Mikael
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