From: Jiri Olsa <jolsa@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Jiri Olsa <jolsa@kernel.org>,
linux-kernel@vger.kernel.org, Andi Kleen <andi@firstfloor.org>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Corey Ashford <cjashfor@linux.vnet.ibm.com>,
David Ahern <dsahern@gmail.com>,
Frederic Weisbecker <fweisbec@gmail.com>,
Ingo Molnar <mingo@kernel.org>,
"Jen-Cheng(Tommy) Huang" <tommy24@gatech.edu>,
Namhyung Kim <namhyung@kernel.org>,
Paul Mackerras <paulus@samba.org>,
Stephane Eranian <eranian@google.com>
Subject: Re: [PATCH 2/9] perf: Deny optimized switch for events read by PERF_SAMPLE_READ
Date: Mon, 8 Sep 2014 18:39:33 +0200 [thread overview]
Message-ID: <20140908163933.GI17728@krava.brq.redhat.com> (raw)
In-Reply-To: <20140908101119.GB6758@twins.programming.kicks-ass.net>
On Mon, Sep 08, 2014 at 12:11:19PM +0200, Peter Zijlstra wrote:
> On Mon, Sep 08, 2014 at 12:00:19PM +0200, Jiri Olsa wrote:
>
> > > no.. so the value of the counter is the sum of all the inherited events.
> > > It doesn't matter if you flip it or not the sum is not affected.
> > >
> > > PERF_SAMPLE_READ should return the value.
> >
> > so I want to be able to do the leader sampling over child processes
> > that means:
> > - have event group with sampling leader, and the rest
> > of the group events' periods being read on leader's sample
> > via PERF_SAMPLE_READ sample_type
> > - for each child process created I want it to do the
> > same thing as the parent - sample on leader, read
> > values of other events in group via PERF_SAMPLE_READ
>
> The thing is, PERF_SAMPLE_READ should return the exact same thing as an
> actual read(), and for read() the value reported is the sum of all
> events.
maybe we could make this configurable? like via new per_event_attr::option bit,
keeping by default the behaviour you said
>
> I _think_ I know what you want, and I think I see why you'd want that,
> but I'm not sure how to best do that.. Hmm.. maybe look at
> 'perf_event_attr::inherit_stat' that appears to be similar.
>
> At which point read() vs inherit_stat might be 'broken'. Hard to know if
> anybody uses that :-(
I'll check, thanks
jirka
next prev parent reply other threads:[~2014-09-08 16:40 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-25 14:45 [RFCv2 0/9] perf: Allow leader sampling on inherited events Jiri Olsa
2014-08-25 14:45 ` [PATCH 1/9] perf: Remove redundant parent context check from context_equiv Jiri Olsa
2014-09-02 10:50 ` Peter Zijlstra
2014-09-08 9:43 ` Jiri Olsa
2014-09-08 9:45 ` Peter Zijlstra
2014-09-08 9:48 ` Peter Zijlstra
2014-09-08 10:01 ` Peter Zijlstra
2014-09-08 11:39 ` Peter Zijlstra
2014-09-08 12:19 ` Jiri Olsa
2014-09-08 13:20 ` Peter Zijlstra
2014-09-08 12:32 ` Jiri Olsa
2014-09-08 12:01 ` Jiri Olsa
2014-09-08 13:34 ` Peter Zijlstra
2014-09-08 15:13 ` Peter Zijlstra
2014-09-08 16:45 ` Jiri Olsa
2014-09-09 10:20 ` Peter Zijlstra
2014-09-10 13:57 ` Peter Zijlstra
2014-09-10 14:35 ` Jiri Olsa
2014-09-24 14:58 ` [tip:perf/core] Revert "perf: Do not allow optimized switch for non-cloned events" tip-bot for Jiri Olsa
2014-08-25 14:45 ` [PATCH 2/9] perf: Deny optimized switch for events read by PERF_SAMPLE_READ Jiri Olsa
2014-09-02 10:52 ` Peter Zijlstra
2014-09-08 10:00 ` Jiri Olsa
2014-09-08 10:11 ` Peter Zijlstra
2014-09-08 16:39 ` Jiri Olsa [this message]
2014-08-25 14:45 ` [PATCH 3/9] perf: Allow PERF_FORMAT_GROUP format on inherited events Jiri Olsa
2014-08-25 14:45 ` [PATCH 4/9] perf tools: Add support to traverse xyarrays Jiri Olsa
2014-08-25 14:45 ` [PATCH 5/9] perf tools: Add pr_warning_once debug macro Jiri Olsa
2014-08-25 14:45 ` [PATCH 6/9] perf tools: Add hash of periods for struct perf_sample_id Jiri Olsa
2014-08-25 14:45 ` [PATCH 7/9] perf tools: Allow PERF_FORMAT_GROUP for inherited events Jiri Olsa
2014-08-25 14:45 ` [PATCH 8/9] perf script: Add period data column Jiri Olsa
2014-08-27 14:33 ` David Ahern
2014-10-17 16:10 ` Jiri Olsa
2014-10-17 18:22 ` Arnaldo Carvalho de Melo
2014-10-18 7:07 ` [tip:perf/urgent] " tip-bot for Jiri Olsa
2014-08-25 14:45 ` [PATCH 9/9] perf script: Add period as a default output column Jiri Olsa
2014-08-27 14:40 ` David Ahern
2014-10-17 16:11 ` Jiri Olsa
2014-10-18 7:07 ` [tip:perf/urgent] " tip-bot for Jiri Olsa
2014-08-25 14:51 ` [RFCv2 0/9] perf: Allow leader sampling on inherited events Jiri Olsa
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