linux-kernel - Re: [PATCH 5/5] perf, x86: Support Haswell v4 LBR format v2

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Message-ID: <alpine.DEB.2.02.1309041015130.28706@pianoman.cluster.toy>
Date:	Wed, 4 Sep 2013 10:21:27 -0400 (EDT)
From:	Vince Weaver <vince@...ter.net>
To:	Andi Kleen <andi@...stfloor.org>
cc:	Andi Kleen <ak@...ux.intel.com>, mingo@...e.hu,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 5/5] perf, x86: Support Haswell v4 LBR format v2

On Wed, 4 Sep 2013, Andi Kleen wrote:

> > What does this mean?  The above values are exported as part of 
> >   include/uapi/linux/perf_event.h
> > Do they not work yet?
> 
> You can filter on the fields, but you can't see them outside
> the kernel driver yet.  The patch to see them is still pending.

so you can filter for aborts, but they'll never show up in the lbr[]
sample buffer?

> > > >  What happens if you set both in transaction and not in?
> > > 
> > > Then you get all branches.
> > 
> > so what happens if you set neither "PERF_SAMPLE_BRANCH_IN_TX" nor
> > "PERF_SAMPLE_BRANCH_NO_TX"?  Logically you'd get no branches at all,
> > but that can't be true as all code prior to 3.11 didn't set those values.
> 
> Then you get all branches too
> 
> (that's how all the other filters work too)

This is a really confusing API

so does setting "PERF_SAMPLE_BRANCH_ANY" also enable all of the TX types?

Is leaving branch_sample_type at 0 the same as setting it to all 1s?

Vince


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