linux-kernel - Re: [RFC/PATCH v2] perf data: Add stat subcommand to show sample event stat

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Message-ID: <20150511154405.GV2366@two.firstfloor.org>
Date:	Mon, 11 May 2015 17:44:05 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	Namhyung Kim <namhyung@...nel.org>
Cc:	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Jiri Olsa <jolsa@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>,
	David Ahern <dsahern@...il.com>,
	Stephane Eranian <eranian@...gle.com>,
	Andi Kleen <andi@...stfloor.org>,
	Minchan Kim <minchan@...nel.org>
Subject: Re: [RFC/PATCH v2] perf data: Add stat subcommand to show sample
 event stat

> The sampling ratio was useful for me to determine how often the event
> was sampled - in this case the cpu cycles event was only sampled at 12%

That's dangerous to determine without a plot. It could be that it was bimodal: 
100% busy and then idle. You may want to add something like the spark
plots I submitted for stat some time ago.

-Andi
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