From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755229Ab2BHJoI (ORCPT ); Wed, 8 Feb 2012 04:44:08 -0500 Received: from e23smtp08.au.ibm.com ([202.81.31.141]:37533 "EHLO e23smtp08.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751074Ab2BHJoG (ORCPT ); Wed, 8 Feb 2012 04:44:06 -0500 Message-ID: <4F3243D4.4080907@linux.vnet.ibm.com> Date: Wed, 08 Feb 2012 15:13:48 +0530 From: Anshuman Khandual User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.2.17) Gecko/20110424 Thunderbird/3.1.10 MIME-Version: 1.0 To: Stephane Eranian CC: linux-kernel@vger.kernel.org, peterz@infradead.org, mingo@elte.hu Subject: Use case for PERF_COUNT_HW_REF_CPU_CYCLES generic PMU event Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit x-cbid: 12020723-5140-0000-0000-000000B774F8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Stephane, I was going through the following discussion where we added the new HW generic event PERF_COUNT_HW_REF_CPU_CYCLES. https://lkml.org/lkml/2011/12/10/103 (Sorry, for asking this question bit late) I am trying to understand the use case for this. Would this new event help us in generating (during a perf session) a CPU frequency invariant time metric against which we would plot our other perf event's measurements ? CPU frequency independent time measurement is it's primary purpose ? or we were finding a way to expose the fixed counter 2 which was not getting used before for not having an event encoding. I guess this would help us in finding equivalent PMU events or mechanisms in other architecture / platforms. -- Anshuman Khandual Linux Technology Centre IBM Systems and Technology Group