RE: [Xen-devel] How expensive is a VM EXIT?

["Nadolski, Ed" <Ed.Nadolski@xxxxxxx>]

Is there a good tool to look at for this -- xentrace, xenoprofile, other?

Thanks,
Ed

-----Original Message-----
From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx 
[mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Keir Fraser
Sent: Wednesday, March 04, 2009 1:46 AM
To: NAHieu
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-devel] How expensive is a VM EXIT?

On 04/03/2009 00:15, "NAHieu" <nahieu@xxxxxxxxx> wrote:

> On Wed, Mar 4, 2009 at 1:34 AM, Keir Fraser <keir.fraser@xxxxxxxxxxxxx> wrote:
>> For just the VMEXIT itself, it's probably about 1000-1500 cycles on the
>> latest processors. I haven't measured it very recently though.
>> 
> 
> Could you explain how do you measure the cycles for VMEXIT?

RDTSC in the guest immediately before triggering a VMEXIT and RDTSC in the
hypervisor on entry.

 -- Keir



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