linux-kernel - Re: [RFC] perf: perf record sets inherit by default

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Date:	Tue, 11 May 2010 12:50:39 -0300
From:	Arnaldo Carvalho de Melo <acme@...radead.org>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Stephane Eranian <eranian@...gle.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Frédéric Weisbecker <fweisbec@...il.com>,
	mingo@...e.hu, Paul Mackerras <paulus@...ba.org>,
	"David S. Miller" <davem@...emloft.net>,
	perfmon2-devel@...ts.sf.net
Subject: Re: [RFC] perf: perf record sets inherit by default

Em Tue, May 11, 2010 at 05:13:20PM +0200, Peter Zijlstra escreveu:
> On Tue, 2010-05-11 at 12:00 -0300, Arnaldo Carvalho de Melo wrote:
> > Humm, since for -C and -a using -i doesn't make sense, I guess it should
> > be off by default and only be auto-activated if we don't specify any
> > option, i.e. when using it like:

> > perf record ./hackbench
 
> -ENOPARSE
 
> -a/-C usage creates per-cpu counters and will thus ignore any and all
> perf_event_attr::inherit state.

What I tried to say was that if one does:

perf record -t 1234

then inherit would be off, or if:

perf record -p 5678

it would also be off.

but when just pass some program to run, like in:

perf record make -j allmodconfig

we would then assume that the user is interested in everything that the
program perf is starting does, i.e. the user is interested in the whole
workload started from perf, thus we would auto-enable -i.

> Your above suggestion would still have inherit enabled by default, and
> would thus not change anything.

Nope, see above.
 
- Arnaldo
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