From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030413AbcBQQKQ (ORCPT ); Wed, 17 Feb 2016 11:10:16 -0500 Received: from www.linutronix.de ([62.245.132.108]:44727 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756275AbcBQQKN (ORCPT ); Wed, 17 Feb 2016 11:10:13 -0500 Date: Wed, 17 Feb 2016 17:08:57 +0100 (CET) From: Thomas Gleixner To: LKML cc: Peter Zijlstra , x86@kernel.org, Stephane Eranian , Matt Fleming , Vikas Shivappa Subject: Re: [PATCH] x86/perf/intel/cqm: Get rid of the silly for_each_cpu lookups In-Reply-To: Message-ID: References: User-Agent: Alpine 2.11 (DEB 23 2013-08-11) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001,URIBL_BLOCKED=0.001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 17 Feb 2016, Thomas Gleixner wrote: > CQM is a strict per package facility. Use the proper cpumasks to lookup the > readers. Sorry for the noise. PEBKAC: quilt refresh missing. Correct version below. Thanks, tglx 8<---------- Subject: x86/perf/cqm: Get rid of the silly for_each_cpu lookups From: Thomas Gleixner Date: Sun, 14 Feb 2016 23:09:06 +0100 CQM is a strict per package facility. Use the proper cpumasks to lookup the readers. Signed-off-by: Thomas Gleixner --- arch/x86/kernel/cpu/perf_event_intel_cqm.c | 34 ++++++++++------------------- 1 file changed, 12 insertions(+), 22 deletions(-) --- a/arch/x86/kernel/cpu/perf_event_intel_cqm.c +++ b/arch/x86/kernel/cpu/perf_event_intel_cqm.c @@ -1244,15 +1244,12 @@ static struct pmu intel_cqm_pmu = { static inline void cqm_pick_event_reader(int cpu) { - int phys_id = topology_physical_package_id(cpu); - int i; + int reader; - for_each_cpu(i, &cqm_cpumask) { - if (phys_id == topology_physical_package_id(i)) - return; /* already got reader for this socket */ - } - - cpumask_set_cpu(cpu, &cqm_cpumask); + /* First online cpu in package becomes the reader */ + reader = cpumask_any_and(topology_core_cpumask(cpu), &cqm_cpumask); + if (reader >= nr_cpu_ids) + cpumask_set_cpu(cpu, &cqm_cpumask); } static void intel_cqm_cpu_starting(unsigned int cpu) @@ -1270,24 +1267,17 @@ static void intel_cqm_cpu_starting(unsig static void intel_cqm_cpu_exit(unsigned int cpu) { - int phys_id = topology_physical_package_id(cpu); - int i; + int target; - /* - * Is @cpu a designated cqm reader? - */ + /* Is @cpu the current cqm reader for this package ? */ if (!cpumask_test_and_clear_cpu(cpu, &cqm_cpumask)) return; - for_each_online_cpu(i) { - if (i == cpu) - continue; - - if (phys_id == topology_physical_package_id(i)) { - cpumask_set_cpu(i, &cqm_cpumask); - break; - } - } + /* Find another online reader in this package */ + target = cpumask_any_but(topology_core_cpumask(cpu), cpu); + + if (target < nr_cpu_ids) + cpumask_set_cpu(target, &cqm_cpumask); } static int intel_cqm_cpu_notifier(struct notifier_block *nb,