linux-kernel - Re: [PATCH] perf: add support for per-event sampling period or frequency in perf record

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Date:	Tue, 23 Nov 2010 12:11:20 +0100
From:	Peter Zijlstra <peterz@...radead.org>
To:	eranian@...gle.com
Cc:	linux-kernel@...r.kernel.org, mingo@...e.hu, acme@...hat.com,
	paulus@...ba.org, davem@...emloft.net, fweisbec@...il.com,
	perfmon2-devel@...ts.sf.net, eranian@...il.com,
	robert.richter@....com
Subject: Re: [PATCH] perf: add support for per-event sampling period or
 frequency in perf record

On Tue, 2010-11-23 at 11:45 +0200, Stephane Eranian wrote:
> This patch allows specifying a per event sampling period or frequency.
> Up until now, the same sampling period or frequency was applied to all
> the events specified on the command line of perf record. A sampling 
> period depends on the event, thus it is necessary to specify it per event.
> 
> With this patch, both the -F and -c options now take a comma separated
> list of values. If a value is omitted for an event, it defaults to 1000Hz
> frequency mode as before.
> 
> $ perf record -e cycles,instructions -c 100000,200000 -a -- sleep 5


I remember an email not too long ago where people proposed to change the
syntax so that:

 -e evnt1,evnt2     -- create a group containing both events
 -e evnt1 -e evnt2  -- create two separate events

It would be nice to make sure these two proposals will not interfere.

Alternatively we extend the event syntax to include the period,
something like:

  -e evnt1:period=1234


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