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Re: [Xen-devel] Dual opteron PIT timing problem?

On Fri, Oct 06, 2006 at 11:47:44PM +0100, Keir Fraser wrote:
> On 6/10/06 10:00 pm, "John Clemens" <jclemens@xxxxxxxxxxxxxxxxx> wrote:
> > Are the any other things I could try? I've tried all sorts of
> > combinations of [no]apic, [no]smp, [no]tsc, [no]lapic, [no]apm, etc.. Is
> > anyone running an SMP xen system without an HPET timer?
> Most people, I should think. Many BIOSes do not advertise the presence of an
> HPET, even if the chipset has one.

Actually there's some pretty common machines which don't include a HPET. IIRC
HP's Opteron based systems such as the DL-{3,5}85 don't typically have a HPET. 
RHEL kernels would typically fallback to using the TSC or the ACPI PMTimer for
these systems (PMTimer is reliable but high overhead, while TSC is low overhead
but pretty tricky to get the code correct to maintain SMP synchronisation).

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