From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Ahern Subject: Re: perf trace Date: Mon, 18 Apr 2011 13:26:28 -0600 Message-ID: <4DAC9064.30604@gmail.com> References: <4D8DE695.3000606@gmail.com> <4D8DF6E4.1070804@gmail.com> <4D8EB605.7070407@gmail.com> <4D8FA787.7020308@gmail.com> <4D923B8D.1020204@gmail.com> <8CB5FB7FBAFD274A8E92A53BBAFE339D0BB25C@039-SN1MPN1-003.039d.mgd.msft.net>,<4DABD54B.5090509@gmai l.com> <8CB5FB7FBAFD274A8E92A53BBAFE339D0BB2AC@039-SN1MPN1-003.039d.mgd.msft.net> <4DABDEAF.7040207@gmail.com> <8CB5FB7FBAFD274A8E92A53BBAFE339D0BB323@039-SN1MPN1-003.039d.mgd.msft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from mail-pv0-f174.google.com ([74.125.83.174]:35286 "EHLO mail-pv0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756610Ab1DRT0a (ORCPT ); Mon, 18 Apr 2011 15:26:30 -0400 Received: by pvg12 with SMTP id 12so2327331pvg.19 for ; Mon, 18 Apr 2011 12:26:30 -0700 (PDT) In-Reply-To: <8CB5FB7FBAFD274A8E92A53BBAFE339D0BB323@039-SN1MPN1-003.039d.mgd.msft.net> Sender: linux-perf-users-owner@vger.kernel.org List-ID: To: Kumar Ranjit-B04060 Cc: "linux-perf-users@vger.kernel.org" On 04/18/11 11:46, Kumar Ranjit-B04060 wrote: > David > > > > meaning periodic samples of the counter? perf-record does not generate periodic reads of H/W counters. > > Just curious, How does then the profiling works? Perf report shows % no of sample point corresponding a particular event. So it must be sampling the PC periodically. > Regards > Ranjit With H/W counters the values of the counters are not read when samples are created. David