From: Tim Blechmann <tim@klingt.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org
Subject: Re: perf: counter and event question
Date: Mon, 28 Dec 2009 13:39:35 +0100 [thread overview]
Message-ID: <4B38A707.4060904@klingt.org> (raw)
In-Reply-To: <1261999573.7135.83.camel@laptop>
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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 ...
> In order to avoid the machine grinding to a halt, we've implemented a
> throttle which defaults to 100k samples/s, anything over that will be
> discarted.
i just found the proc interface for perf_event_max_sample_rate ... it
would be nice to have a short section on the event throttling in
tools/perf/design.txt ...
thanks, tim
--
tim@klingt.org
http://tim.klingt.org
art is short - life is long
Jack Kerouac
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next prev parent reply other threads:[~2009-12-28 12:43 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 [this message]
2009-12-28 13:03 ` Peter Zijlstra
2009-12-28 13:09 ` Tim Blechmann
2009-12-28 14:02 ` Peter Zijlstra
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