Messages in this thread | | | Date | Fri, 17 Feb 2017 18:55:02 +0100 (CET) | From | Thomas Gleixner <> | Subject | Re: [PATCH v2 0/3] x86/vdso: Add Hyper-V TSC page clocksource support |
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On Fri, 17 Feb 2017, Andy Lutomirski wrote: > On Fri, Feb 17, 2017 at 2:14 AM, Vitaly Kuznetsov <vkuznets@redhat.com> wrote: > > Not only. As far as I understand (and I *think* K. Y. pointed this out) > > when VM is migrating to another host TSC page clocksource is disabled for > > extended period of time so we're better off reading from MSR than > > looping here. With regards to VDSO this means reverting to doing normal > > syscall. > > That's a crappy design. The guest really ought to be able to > distinguish "busy, try again" from "bail and use MSR". > > Thomas, I can see valid reasons why the hypervisor might want to > temporarily disable shared page-based timing, but I think it's silly > that it's conflated with indicating "retry".
It's beyond silly if that's the case.
> But if this is indeed the ABI, we're stuck with it.
No argument.
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