From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753305AbdLMQSe (ORCPT ); Wed, 13 Dec 2017 11:18:34 -0500 Received: from mail-qk0-f175.google.com ([209.85.220.175]:46147 "EHLO mail-qk0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750916AbdLMQSc (ORCPT ); Wed, 13 Dec 2017 11:18:32 -0500 X-Google-Smtp-Source: ACJfBotGSrYY8F1HEmyj2cZ7mtfhHY4KmCoLyAvUvZiapzU4/tL2uPOrWHr/DgVr1EboqwtnQZ82rw== Date: Wed, 13 Dec 2017 08:18:29 -0800 From: Tejun Heo To: Peter Zijlstra Cc: Ingo Molnar , Arnaldo Carvalho de Melo , Alexander Shishkin , Jiri Olsa , Namhyung Kim , linux-kernel@vger.kernel.org, kernel-team@fb.com, alexey.budankov@linux.intel.com Subject: Re: [RFC] Sharing PMU counters across compatible events Message-ID: <20171213161829.GV3919388@devbig577.frc2.facebook.com> References: <20171201141950.GB2421075@devbig577.frc2.facebook.com> <20171206123500.nl5pixkkmc5joacq@hirez.programming.kicks-ass.net> <20171211154744.GK2421075@devbig577.frc2.facebook.com> <20171212223736.llqgzpit4n2klhwg@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20171212223736.llqgzpit4n2klhwg@hirez.programming.kicks-ass.net> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, Peter. On Tue, Dec 12, 2017 at 11:37:36PM +0100, Peter Zijlstra wrote: > That would be a fairly massive change from how perf works today. And the > obvious pain point would be changing the per-cpu event set, which would > mean recomputing all possible combinations of task sets. > > Also note that each context (cpu,task) is allowed to have more events > than fit on the PMU, at which point we'll start rotating events. Do we > also pre-compute all possible rotation sets? > > Just not quite seeing this.. Yeah, right. Will think more about it Thanks. -- tejun