Messages in this thread | | | Date | Wed, 17 Nov 2004 11:43:26 +0100 | From | Mikael Pettersson <> | Subject | RE: [patch] prefer TSC over PM Timer |
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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.
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