linux-kernel - Re: perf: counter and event question

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Message-ID: <1262005413.7135.98.camel@laptop>
Date:	Mon, 28 Dec 2009 14:03:33 +0100
From:	Peter Zijlstra <peterz@...radead.org>
To:	Tim Blechmann <tim@...ngt.org>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: perf: counter and event question

On Mon, 2009-12-28 at 13:39 +0100, Tim Blechmann wrote:
> On 12/28/2009 12:26 PM, Peter Zijlstra wrote:
> > On Mon, 2009-12-28 at 12:16 +0100, Tim Blechmann wrote:
> >> like it is impossible to sample instructions with a period of 1? 
> > 
> > Pretty much, imagine the cpu getting a trap every cycle.
> 
> is this a hardware restriction? a slowdown is acceptable for me, as long
> as i am able to collect a huge number of samples accurately ...

Large number of samples and sample interval are only related through the
runtime of your application.

Use a sensible period (~10k ins) and run a 'little' longer.



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