From: Peter Zijlstra <peterz@infradead.org>
To: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: "Stephane Eranian" <eranian@google.com>,
LKML <linux-kernel@vger.kernel.org>,
"Frédéric Weisbecker" <fweisbec@gmail.com>,
mingo@elte.hu, "Paul Mackerras" <paulus@samba.org>,
"David S. Miller" <davem@davemloft.net>,
perfmon2-devel@lists.sf.net
Subject: Re: [RFC] perf: perf record sets inherit by default
Date: Tue, 11 May 2010 17:13:20 +0200 [thread overview]
Message-ID: <1273590800.1810.19.camel@laptop> (raw)
In-Reply-To: <20100511150052.GE19192@ghostprotocols.net>
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
>
> What do you think?
-ENOPARSE
-a/-C usage creates per-cpu counters and will thus ignore any and all
perf_event_attr::inherit state.
Your above suggestion would still have inherit enabled by default, and
would thus not change anything.
The thing is that perf-record defaults to inherited per-task-per-cpu
counters, which, I think, is a reasonable default, just sub-optimal for
single threaded/!forking subjects.
So what would make sense is for -i to mean --no-inherit, and for !
inherit create a per-task counter instead of a per-task-per-cpu counter.
next prev parent reply other threads:[~2010-05-11 15:13 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-11 14:04 [RFC] perf: perf record sets inherit by default Stephane Eranian
2010-05-11 14:48 ` Peter Zijlstra
2010-05-17 14:25 ` Stephane Eranian
2010-05-17 16:48 ` Peter Zijlstra
2010-05-18 17:16 ` [tip:perf/core] perf: Optimize buffer placement by allocating buffers NUMA aware tip-bot for Peter Zijlstra
2010-05-11 15:00 ` [RFC] perf: perf record sets inherit by default Arnaldo Carvalho de Melo
2010-05-11 15:13 ` Peter Zijlstra [this message]
2010-05-11 15:17 ` Stephane Eranian
2010-05-11 15:50 ` Arnaldo Carvalho de Melo
2010-05-11 15:52 ` Peter Zijlstra
2010-05-11 15:55 ` Stephane Eranian
2010-05-11 15:59 ` Arnaldo Carvalho de Melo
2010-05-11 15:56 ` Arnaldo Carvalho de Melo
2010-05-11 16:01 ` Stephane Eranian
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