Messages in this thread | | | Date | Fri, 13 Jan 2006 10:55:33 -0800 | From | thockin@hockin ... | Subject | Re: Dual core Athlons and unsynced TSCs |
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On Fri, Jan 13, 2006 at 01:09:51PM -0500, Lee Revell wrote: > > Some apps/users need higher resolution and lower overhead that only rdtsc > > can offer currently. > > But obviously if the TSC gives wildly inaccurate results, it cannot be > used no matter how low the overhead.
unless we can re-sync the TSCs often enough that apps don't notice.
> > I never tried it with pmtimer, we had HPET available. Empirically TSC did > > not work (and we had a simple test case to show how bad it could get). > > HPET made that go away for users of gettimeofday(). > > > > We're exploring rdtsc-compatible solutions. > > > > Since timekeeping on these machines has always been completely broken, > shouldn't the default time source have been changed to the PM timer or > HPET as soon as the problem was known?
If you have HPET, the kernel will prefer that. I don't know enough about the PMtimer overhead or resolution to say for sure. - 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/
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