Messages in this thread | | | Subject | Re: [PATCH 3/5] lockstat: core infrastructure | From | Andi Kleen <> | Date | 01 Jun 2007 16:25:47 +0200 |
| |
Daniel Walker <dwalker@mvista.com> writes:
> On Wed, 2007-05-30 at 19:16 +0200, Peter Zijlstra wrote: > > > > >From the architecture perspective there are two low level clock hooks to > > > implement one is sched_clock() , and at least one clocksource structure. > > > Both do essentially the same thing. With timekeepings clocksource > > > structure actually being easier to implement cause the math is built in. > > > > I think you are mistaken here; the two are similar but not identical. > > > > I see sched_clock() as fast first, accurate second. Whereas the > > clocksource thing is accurate first, fast second. > > This is true .. However, if there is a speed different it's small.
pmtimer (factor 1000+) or HPET (factor 10-100+ depending on CPU) accesses are much slower than TSC or jiffies read. Talking to the southbridge is slow.
-Andi - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |