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Message-ID: <4BA00DE5.80604@redhat.com>
Date: Tue, 16 Mar 2010 19:01:57 -0400
From: Masami Hiramatsu <mhiramat@...hat.com>
To: oerg Roedel <joro@...tes.org>
CC: Ingo Molnar <mingo@...e.hu>, Avi Kivity <avi@...hat.com>,
"Zhang, Yanmin" <yanmin_zhang@...ux.intel.com>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>,
Sheng Yang <sheng@...ux.intel.com>,
linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
Marcelo Tosatti <mtosatti@...hat.com>,
Jes Sorensen <Jes.Sorensen@...hat.com>,
Gleb Natapov <gleb@...hat.com>,
Zachary Amsden <zamsden@...hat.com>, ziteng.huang@...el.com,
sungho.kim.zd@...achi.com
Subject: Re: [PATCH] Enhance perf to collect KVM guest os statistics from
host side
oerg Roedel wrote:
> On Tue, Mar 16, 2010 at 12:25:00PM +0100, Ingo Molnar wrote:
>> 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? Can we trust it? 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?
>
> Since we want to implement a pmu usable for the guest anyway why we
> don't just use a guests perf to get all information we want? If we get a
> pmu-nmi from the guest we just re-inject it to the guest and perf in the
> guest gives us all information we wand including kernel and userspace
> symbols, stack traces, and so on.
I guess this aims to get information from old environments running on
kvm for life extension :)
> In the previous thread we discussed about a direct trace channel between
> guest and host kernel (which can be used for ftrace events for example).
> This channel could be used to transport this information to the host
> kernel.
Interesting! I know the people who are trying to do that with systemtap.
See, http://vesper.sourceforge.net/
>
> The only additional feature needed is a way for the host to start a perf
> instance in the guest.
# ssh localguest perf record --host-chanel ... ? B-)
Thank you,
>
> Opinions?
>
>
> Joerg
>
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--
Masami Hiramatsu
e-mail: mhiramat@...hat.com
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