Re: [PATCH] Enhance perf to collect KVM guest os statistics from host side

Avi Kivity
2010-03-16T12:22:16Z

On 03/16/2010 01:25 PM, Ingo Molnar wrote:
>
>> I haven't followed vmchannel closely, but I think it is. vmchannel is
>> terminated in qemu on the host side, not in the host kernel. So perf would
>> need to connect to qemu.
>>
> Hm, that sounds rather messy if we want to use it to basically expose kernel
> functionality in a guest/host unified way. Is the qemu process discoverable in
> some secure way?

We know its pid.

> Can we trust it?

No choice, it contains the guest address space.

> Is there some proper tooling available to do
> it, or do we have to push it through 2-3 packages to get such a useful feature
> done?
>

libvirt manages qemu processes, but I don't think this should go through
libvirt. qemu can do this directly by opening a unix domain socket in a
well-known place.

> ( That is the general thought process how many cross-discipline useful
> desktop/server features hit the bit bucket before having had any chance of
> being vetted by users, and why Linux sucks so much when it comes to feature
> integration and application usability. )
>

You can't solve everything in the kernel, even with a well populated tools/.

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