From mboxrd@z Thu Jan  1 00:00:00 1970
From: Marcelo Tosatti <mtosatti@redhat.com>
Subject: Re: invtsc + migration + TSC scaling
Date: Mon, 17 Oct 2016 21:58:49 -0200
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Cc: Paolo Bonzini <pbonzini@redhat.com>,
        Radim =?utf-8?B?S3LEjW3DocWZ?= <rkrcmar@redhat.com>,
        qemu-devel@nongnu.org, kvm@vger.kernel.org
To: Eduardo Habkost <ehabkost@redhat.com>
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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 Krčmář 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).
> > 
> > ... and 1 too.
> > 
> > We should also blacklist the TSC deadline timer when invtsc is not
> > available.

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

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.
> 
> -- 
> Eduardo