From mboxrd@z Thu Jan  1 00:00:00 1970
From: Avi Kivity <avi@redhat.com>
Subject: Re: [PATCH] Enhance perf to collect KVM guest os statistics from
 host side
Date: Tue, 16 Mar 2010 14:21:59 +0200
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Cc: "Zhang, Yanmin" <yanmin_zhang@linux.intel.com>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	Sheng Yang <sheng@linux.intel.com>,
	linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
	Marcelo Tosatti <mtosatti@redhat.com>,
	oerg Roedel <joro@8bytes.org>,
	Jes Sorensen <Jes.Sorensen@redhat.com>,
	Gleb Natapov <gleb@redhat.com>,
	Zachary Amsden <zamsden@redhat.com>, ziteng.huang@intel.com
To: Ingo Molnar <mingo@elte.hu>
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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/.

-- 
error compiling committee.c: too many arguments to function