Re: perf: counter and event question
From: Tim Blechmann
Date: Mon Dec 28 2009 - 07:43:40 EST
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@xxxxxxxxxx
http://tim.klingt.org
art is short - life is long
Jack Kerouac
Attachment:
signature.asc
Description: OpenPGP digital signature