From: Peter Zijlstra <peterz@infradead.org>
To: Tim Blechmann <tim@klingt.org>
Cc: linux-kernel@vger.kernel.org
Subject: Re: perf: counter and event question
Date: Mon, 28 Dec 2009 15:02:12 +0100 [thread overview]
Message-ID: <1262008932.7135.101.camel@laptop> (raw)
In-Reply-To: <4B38AE1D.8060703@klingt.org>
On Mon, 2009-12-28 at 14:09 +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.
>
> well, for my application, i am not interested in statistical data, but
> in the order of the events ...
> (i am not doing profiling, but trying to gather a sequence of
> machine-structured data for an artistic project)
Well, then use the branch tracer, that will give you the relation
between blocks of code and is actually doable.
But I guess you could hack out the throttle and run the cycle counter
with period=1 for userspace only.
prev parent reply other threads:[~2009-12-28 14:02 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-12-28 11:16 perf: counter and event question Tim Blechmann
2009-12-28 11:26 ` Peter Zijlstra
2009-12-28 12:39 ` Tim Blechmann
2009-12-28 13:03 ` Peter Zijlstra
2009-12-28 13:09 ` Tim Blechmann
2009-12-28 14:02 ` Peter Zijlstra [this message]
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