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From: Namhyung Kim <namhyung@kernel.org>
To: "Vuille, Martin (Martin)" <vmartin@avaya.com>
Cc: "linux-perf-users@vger.kernel.org"
	<linux-perf-users@vger.kernel.org>,
	kernel-team@lge.com
Subject: Re: perf sched record with -p option
Date: Thu, 8 Feb 2018 14:07:08 +0900	[thread overview]
Message-ID: <20180208050708.GC24686@sejong> (raw)
In-Reply-To: <30C2D590D16A5C46ADFE65219103779892616691@AZ-US1EXMB02.global.avaya.com>

Hello,

On Sun, Feb 04, 2018 at 05:31:07PM +0000, Vuille, Martin (Martin) wrote:
> The data files collected by 'perf sched record' are very large and our embedded
> system target has limited storage, so I thought of using the '-p PID' option on
> 'perf sched record' to focus only on a single PID and its threads/children and
> thus reduce the amount of data.
> 
> However, when I review the results with 'perf sched latency', the results from
> data collected with '-p PID' are significantly different (e.g., ten-times longer
> latencies) that those from data collected without the '-p PID' option. Workloads
> are the same.
> 
> Is there some reason why using '-p PID' option on 'perf sched record' wouldn't
> make sense?

I think it's because perf missed sched-in and wakeup events for the PID
since they are from different tasks.

Thanks,
Namhyung

  reply	other threads:[~2018-02-08  5:07 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-02-04 17:31 perf sched record with -p option Vuille, Martin (Martin)
2018-02-08  5:07 ` Namhyung Kim [this message]
2018-02-13 13:11   ` Vuille, Martin (Martin)

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