Re: [Qemu-devel] [PATCH, RFC] trace: implement guest tracepoint passthrough

[Dhaval Giani]

On Sat, Sep 3, 2011 at 1:53 AM, Blue Swirl <address@hidden> wrote:
> On Wed, Aug 31, 2011 at 6:00 PM, Dhaval Giani <address@hidden> wrote:
>> On Wed, Aug 31, 2011 at 10:58 AM, Blue Swirl <address@hidden> wrote:
>>> On Wed, Aug 31, 2011 at 8:38 AM, Avi Kivity <address@hidden> 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.  IMO, for
>>>> kvm, even one exit per tracepoint is too high.  We need to use a shared
>>>> memory transport with a way to order guest/host events later on (by using 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.
>
> It's only available for KVM on x86, that is most certainly not enough.
>

>From what I understood it is available on other architectures as well,
but let us just confirm with glommer.

Thanks!
Dhaval