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From: Peter Zijlstra <peterz@infradead.org>
To: kan.liang@intel.com
Cc: mingo@redhat.com, acme@kernel.org, linux-kernel@vger.kernel.org,
	alexander.shishkin@linux.intel.com, tglx@linutronix.de,
	namhyung@kernel.org, jolsa@kernel.org, adrian.hunter@intel.com,
	wangnan0@huawei.com, mark.rutland@arm.com, andi@firstfloor.org
Subject: Re: [PATCH V2 02/13] perf/core: output overhead when sched out from context
Date: Tue, 6 Dec 2016 12:21:07 +0100	[thread overview]
Message-ID: <20161206112107.GK3124@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <1480713561-6617-3-git-send-email-kan.liang@intel.com>

On Fri, Dec 02, 2016 at 04:19:10PM -0500, kan.liang@intel.com wrote:
> From: Kan Liang <kan.liang@intel.com>
> 
> Outputing every overhead when it happens is very costly. The accumulated
> time is more meaningful. So the overhead information should be outputted
> at the very end.
> 
> The overhead information is outputted when task is scheduling out or the
> event is going to be disabled.

Why? The context switch stuff can happen very frequently. Doesn't seem
like a good place to add overhead.

> The arch specific overhead is outputted in event pmu delete, when Flag
> PERF_EF_LOG is set.

  reply	other threads:[~2016-12-06 11:21 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-12-02 21:19 [PATCH V2 00/13] export perf overheads information kan.liang
2016-12-02 21:19 ` [PATCH V2 01/13] perf/core: Introduce PERF_RECORD_OVERHEAD kan.liang
2016-12-06 11:26   ` Peter Zijlstra
2016-12-02 21:19 ` [PATCH V2 02/13] perf/core: output overhead when sched out from context kan.liang
2016-12-06 11:21   ` Peter Zijlstra [this message]
2016-12-02 21:19 ` [PATCH V2 03/13] perf/x86: output sampling overhead kan.liang
2016-12-06 11:20   ` Peter Zijlstra
2016-12-06 15:02     ` Liang, Kan
2016-12-06 15:32       ` Peter Zijlstra
2016-12-06 15:47         ` Liang, Kan
2016-12-06 18:26           ` Peter Zijlstra
2016-12-07 19:03             ` Liang, Kan
2016-12-06 11:38   ` Peter Zijlstra
2016-12-02 21:19 ` [PATCH V2 04/13] perf/core: output multiplexing overhead kan.liang
2016-12-06 11:23   ` Peter Zijlstra
2016-12-06 15:04     ` Liang, Kan
2016-12-02 21:19 ` [PATCH V2 05/13] perf/core: output side-band events overhead kan.liang
2016-12-06 11:25   ` Peter Zijlstra
2016-12-02 21:19 ` [PATCH V2 06/13] perf tools: option to disable overhead collection kan.liang
2016-12-02 21:19 ` [PATCH V2 07/13] perf tools: handle PERF_RECORD_OVERHEAD record type kan.liang
2016-12-06 11:16   ` Jiri Olsa
2016-12-02 21:19 ` [PATCH V2 08/13] perf tools: show kernel overhead kan.liang
2016-12-06 11:16   ` Jiri Olsa
2016-12-06 11:16   ` Jiri Olsa
2016-12-06 11:16   ` Jiri Olsa
2016-12-02 21:19 ` [PATCH V2 09/13] perf script: " kan.liang
2016-12-04 21:25   ` Jiri Olsa
2016-12-05 14:47     ` Liang, Kan
2016-12-02 21:19 ` [PATCH V2 10/13] perf tools: add time related functions kan.liang
2016-12-06 11:16   ` Jiri Olsa
2016-12-02 21:19 ` [PATCH V2 11/13] perf tools: introduce PERF_RECORD_USER_OVERHEAD kan.liang
2016-12-02 21:19 ` [PATCH V2 12/13] perf tools: record user space profiling cost kan.liang
2016-12-02 21:19 ` [PATCH V2 13/13] perf report: warn on high overhead kan.liang

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