Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933483AbcDYUFV (ORCPT ); Mon, 25 Apr 2016 16:05:21 -0400 Received: from merlin.infradead.org ([205.233.59.134]:43600 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933160AbcDYUFU (ORCPT ); Mon, 25 Apr 2016 16:05:20 -0400 Date: Mon, 25 Apr 2016 22:05:12 +0200 From: Peter Zijlstra To: Vikas Shivappa Cc: Vikas Shivappa , tony.luck@intel.com, "Shankar, Ravi V" , "Yu, Fenghua" , x86@kernel.org, linux-kernel@vger.kernel.org, hpa@zytor.com, tglx@linutronix.de, mingo@kernel.org, h.peter.anvin@intel.com Subject: Re: [PATCH 3/4] perf/x86/mbm: Fix mbm counting when RMIDs are reused Message-ID: <20160425200512.GN3448@twins.programming.kicks-ass.net> References: <1461371241-4258-1-git-send-email-vikas.shivappa@linux.intel.com> <1461371241-4258-4-git-send-email-vikas.shivappa@linux.intel.com> <20160425091656.GF3430@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1114 Lines: 29 On Mon, Apr 25, 2016 at 09:44:53AM -0700, Vikas Shivappa wrote: > > > On Mon, 25 Apr 2016, Peter Zijlstra wrote: > > >On Fri, Apr 22, 2016 at 05:27:20PM -0700, Vikas Shivappa wrote: > >>When multiple instances of perf reuse RMID, then we need to start > >>counting for each instance rather than reporting the current RMID count. > >>This patch adds a st_count(start count) per event to track the same. > > > >what? > > > > Will fix the comit log : > > When multiple instances of perf reuse RMID for the same PID, then we need to > start counting from zero for each new event, rather than reporting the > current RMID. This patch adds a st_count(start count) per event to track the > same. > > For ex: > 1.RMID1's total_bytes is 100MB for event1(PID1) > 2.another perf instance starts measuring the same PID1 with event2. We reuse > RMID1 as the PID1 is already counted. > 3.event2 stores st_count as 100MB. > 4.After some time, when user wants to count event2 and say RMID1's current > total_bytes 110MB, we report 110MB - 100MB = 10MB This is naturally handled by the scheme I outlined in the other patch.