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Date: Tue, 19 Jul 2011 16:14:59 +0200
From: Joerg Roedel <joro@8bytes.org>
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Subject: Re: [Qemu-devel] [PATCH 2/3] qemu-x86: Add tsc_freq option to -cpu
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To: Avi Kivity <avi@redhat.com>
Cc: Joerg Roedel <joerg.roedel@amd.com>, Marcelo Tosatti <mtosatti@redhat.com>, qemu-devel@nongnu.org, kvm@vger.kernel.org

On Tue, Jul 19, 2011 at 04:55:53PM +0300, Avi Kivity wrote:
> On 07/19/2011 04:54 PM, Avi Kivity wrote:
>> On 07/19/2011 04:30 PM, Joerg Roedel wrote:

>>> Hmm, I planned to do the VMSTATE thing in a follow-on patch-set. The
>>> plan is to read the VCPU tsc_freq at guest start time on !tsc-scale
>>> hosts and migrate it over so that the destination host can set the
>>> tsc-freq if it supports tsc-scaling.
>>
>> This can be done by a management tool if desired.
>>
>
> Although, if we do this unconditionally (that is, also for tsc-scale  
> hosts) then we get stable tsc even without supplying a tsc frequency  
> argument... need to think about this.

It has the advantage that it "just works", without the need to extend
management tools and the like. And it makes migration more transparent
to the guests.

	Joerg