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Date: Tue, 16 Mar 2010 11:50:21 +0100
From: Ingo Molnar <mingo@elte.hu>
To: Avi Kivity <avi@redhat.com>
Cc: "Zhang, Yanmin" <yanmin_zhang@linux.intel.com>,
       Peter Zijlstra <a.p.zijlstra@chello.nl>,
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       Gleb Natapov <gleb@redhat.com>, Zachary Amsden <zamsden@redhat.com>,
       ziteng.huang@intel.com
Subject: Re: [PATCH] Enhance perf to collect KVM guest os statistics from
 host side
Message-ID: <20100316105021.GA14344@elte.hu>
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* Avi Kivity <avi@redhat.com> wrote:

> On 03/16/2010 12:20 PM, Ingo Molnar wrote:
> >>>>
> >>>>The symbol server's client can certainly access the bits through vmchannel.
> >>>Ok, that would work i suspect.
> >>>
> >>>Would be nice to have the symbol server in tools/perf/ and also make it easy
> >>>to add it to the initrd via a .config switch or so.
> >>>
> >>>That would have basically all of the advantages of being built into the kernel
> >>>(availability, configurability, transparency, hackability), while having all
> >>>the advantages of a user-space approach as well (flexibility, extensibility,
> >>>robustness, ease of maintenance, etc.).
> >>Note, I am not advocating building the vmchannel client into the host
> >>kernel. [...]
> >Neither am i. What i suggested was a user-space binary/executable built in
> >tools/perf and put into the initrd.
> 
> I'm confused - initrd seems to be guest-side.  I was talking about the host 
> side.

host side doesnt need much support - just some client capability in perf 
itself. I suspect vmchannels are sufficiently flexible and configuration-free 
for such purposes? (i.e. like a filesystem in essence)

	Ingo