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Date: Wed, 31 Aug 2011 11:00:28 -0700
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From: Dhaval Giani <dhaval.giani@gmail.com>
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Subject: Re: [Qemu-devel] [PATCH,
	RFC] trace: implement guest tracepoint passthrough
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To: Blue Swirl <blauwirbel@gmail.com>
Cc: qemu-devel <qemu-devel@nongnu.org>, =?ISO-8859-1?Q?Llu=EDs?= <xscript@gmx.net>, Avi Kivity <avi@redhat.com>, Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>

On Wed, Aug 31, 2011 at 10:58 AM, Blue Swirl <blauwirbel@gmail.com> wrote:
> On Wed, Aug 31, 2011 at 8:38 AM, Avi Kivity <avi@redhat.com> wrote:
>> On 08/26/2011 10:06 PM, Blue Swirl wrote:
>>>
>>> Let guests inject tracepoint data via fw_cfg device.
>>>
>>>
>>
>> At least on x86, fw_cfg is pretty slow, involving multiple exits. =A0IMO=
, for
>> kvm, even one exit per tracepoint is too high. =A0We need to use a share=
d
>> memory transport with a way to order guest/host events later on (by usin=
g a
>> clock).
>
> This could be an easy way, if the guest always had access to an
> accurate clock, but that may not be the case.
>

>>From what I understand, kvmclock should be good enoguh for this
purpose. That is what I am using.

Dhaval