linux-kernel - Re: [PATCHv2 2/9] KVM: Expose a version 2 architectural PMU to a guests

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Message-ID: <20111107171702.GA11367@redhat.com>
Date:	Mon, 7 Nov 2011 19:17:02 +0200
From:	Gleb Natapov <gleb@...hat.com>
To:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc:	kvm@...r.kernel.org, avi@...hat.com, mtosatti@...hat.com,
	linux-kernel@...r.kernel.org, mingo@...e.hu,
	acme@...stprotocols.net
Subject: Re: [PATCHv2 2/9] KVM: Expose a version 2 architectural PMU to a
 guests

On Mon, Nov 07, 2011 at 05:45:14PM +0100, Peter Zijlstra wrote:
> On Mon, 2011-11-07 at 17:25 +0200, Gleb Natapov wrote:
> > > Since the below programming doesn't use perf_event_attr::pinned, yes.
> > > 
> > Yes, that is on todo :). Actually I do want to place all guest perf
> > counters into the same event group and make it pinned. But currently perf
> > event groups are not very flexible. In our usage scenario we can't have
> > one event as a group leader since events are created and destroyed very
> > dynamically. What I would like is to have something like meta event that
> > will group all other real event. 
> 
> Is there a reason to have them grouped if you pin them all anyway?
Hmm good question. May be we shouldn't pin then since this will prevent
profiling vcpu task on a host while perf is running in a guest, but then
we need to group guest created event to get meaningful result. I think I'll
pin them for now and will look into grouping them later.

--
			Gleb.
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