Messages in this thread | | | Date | Wed, 14 Oct 2009 21:32:45 +0900 | From | Avi Kivity <> | Subject | Re: [Xen-devel] Re: [PATCH 3/5] x86/pvclock: add vsyscall implementation |
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On 10/14/2009 05:00 AM, Jeremy Fitzhardinge wrote: > >> So it's broken or disabled when that assumption is wrong? We could >> easily fix that now. Might even reuse the pvclock structures. >> > Well, the kernel internally makes more or less the same assumption; the > vsyscall clocksource is the same as the kernel's internal one. I think > idea is that it just drops back to something like hpet if the tsc > doesn't have very simple SMP characteristics. > > If the kernel could characterize the per-cpu properties of the tsc more > accurately, then it could use the pvclock mechanism on native. >
It does - that's how kvm implements pvclock on the host side. See kvmclock_cpufreq_notifier() in arch/x86/kvm/x86.c.
-- I have a truly marvellous patch that fixes the bug which this signature is too narrow to contain.
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