linux-kernel - Re: [PATCH 4/5] perf record: mmap output file

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Date:	Mon, 18 Nov 2013 19:17:37 -0700
From:	David Ahern <dsahern@...il.com>
To:	Namhyung Kim <namhyung@...nel.org>
CC:	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
	linux-kernel@...r.kernel.org, jolsa@...hat.com,
	Frederic Weisbecker <fweisbec@...il.com>,
	Mike Galbraith <efault@....de>,
	Stephane Eranian <eranian@...gle.com>
Subject: Re: [PATCH 4/5] perf record: mmap output file - v5

On 11/18/13, 7:13 PM, Namhyung Kim wrote:
> I think it should be
>
>    perf record -e cycles -F 4000 -e faults -c 1 --call-graph dwarf,8192 -a -- sleep 1
>
> (at least to generate the feedback spiral more efficiently..)

you don't need the cycles. faults by itself works. Each event contains > 
2 pages of data in the sample. With mmap-based output a single sample (1 
page fault in any process) generates 2-3 page faults by perf which cause 
2-3 >8k samples to be generated, which generates faults, ....

David


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