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Date: Mon, 17 Oct 2016 21:58:49 -0200
From: Marcelo Tosatti <mtosatti@redhat.com>
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Subject: Re: [Qemu-devel] invtsc + migration + TSC scaling
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To: Eduardo Habkost <ehabkost@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>, Radim =?utf-8?B?S3LEjW3DocWZ?= <rkrcmar@redhat.com>, qemu-devel@nongnu.org, kvm@vger.kernel.org

On Mon, Oct 17, 2016 at 07:11:01PM -0200, Eduardo Habkost wrote:
> On Mon, Oct 17, 2016 at 06:24:38PM +0200, Paolo Bonzini wrote:
> > On 17/10/2016 16:50, Radim Kr=C4=8Dm=C3=A1=C5=99 wrote:
> > > 2016-10-17 07:47-0200, Marcelo Tosatti:
> [...]
> > >> since Linux guests use kvmclock and Windows guests use Hyper-V
> > >> enlightenment, it should be fine to disable 2).
> >=20
> > ... and 1 too.
> >=20
> > We should also blacklist the TSC deadline timer when invtsc is not
> > available.

Actually, a nicer fix would be to check the different=20
frequencies and scale the deadline relative to the difference.=20

This would take care of both patched and non-patched guests.

On a related note, what was the goal of Radim's paravirtual deadline
TSC timer?

> You mean on the guest-side? On the host side, it would make
> existing VMs refuse to run.
>=20
> --=20
> Eduardo