linux-kernel - Re: [PATCH 3/3] perf events: add timehist option to record and report

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Date:	Fri, 18 Feb 2011 08:06:57 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	David Ahern <daahern@...co.com>
Cc:	linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
	peterz@...radead.org, acme@...stprotocols.net, paulus@...ba.org,
	Frédéric Weisbecker <fweisbec@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Arnaldo Carvalho de Melo <acme@...hat.com>
Subject: Re: [PATCH 3/3] perf events: add timehist option to record and report


* David Ahern <daahern@...co.com> wrote:

> +--timehist::
> +        Generate time history output. This shows each sample with a wall-clock
> +        timestamp and address to symbol conversions. The samples are output in
> +        the same order they exist in the perf.data file. The --timehist option
> +        must be used with the record to get wall-clock timestamps.

Displaying samples this way is very useful, but how is this different from trace 
output - i.e. 'perf script' output?

There's a 'live logging mode' feature:

    perf record ./myworkload | perf inject -v -b | perf script -i -

( There's also some work going on to have a separate 'perf trace' utility that will
  output a linear trace of whatever events in perf.data are. )

So unless i'm missing something it would be more useful to extend 'perf script' (or 
the upcoming 'perf trace') to list regular samples in a perf.data (i.e. not rely on 
-R raw trace data alone), and of course allow a straightforward utilization of real 
timestamps, when available.

Thanks,

	Ingo
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