Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752500AbbFYT20 (ORCPT ); Thu, 25 Jun 2015 15:28:26 -0400 Received: from mga09.intel.com ([134.134.136.24]:59130 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751603AbbFYT2K (ORCPT ); Thu, 25 Jun 2015 15:28:10 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.13,679,1427785200"; d="scan'208";a="717717650" From: Vikas Shivappa To: linux-kernel@vger.kernel.org Cc: x86@kernel.org, hpa@zytor.com, tglx@linutronix.de, mingo@kernel.org, tj@kernel.org, peterz@infradead.org, matt.fleming@intel.com, will.auld@intel.com, kanaka.d.juvva@intel.com, glenn.p.williamson@intel.com, vikas.shivappa@linux.intel.com, vikas.shivappa@intel.com Subject: [PATCH 1/9] x86/intel_cqm: Modify hot cpu notification handling Date: Thu, 25 Jun 2015 12:25:16 -0700 Message-Id: <1435260324-18125-2-git-send-email-vikas.shivappa@linux.intel.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1435260324-18125-1-git-send-email-vikas.shivappa@linux.intel.com> References: <1435260324-18125-1-git-send-email-vikas.shivappa@linux.intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2602 Lines: 81 This patch modifies hot cpu notification handling in Intel cache monitoring: - to add a new cpu to the cqm_cpumask(which has one cpu per package) during cpu start, it uses the existing package<->core map instead of looping through all cpus in cqm_cpumask. - to search for the next online sibling during cpu exit, it uses the same map instead of looping through all online cpus. In large systems with large number of cpus the time taken to loop may be expensive and also the time increase linearly. Signed-off-by: Vikas Shivappa --- arch/x86/kernel/cpu/perf_event_intel_cqm.c | 29 +++++++++++++---------------- 1 file changed, 13 insertions(+), 16 deletions(-) diff --git a/arch/x86/kernel/cpu/perf_event_intel_cqm.c b/arch/x86/kernel/cpu/perf_event_intel_cqm.c index 1880761..9f4ee29 100644 --- a/arch/x86/kernel/cpu/perf_event_intel_cqm.c +++ b/arch/x86/kernel/cpu/perf_event_intel_cqm.c @@ -1236,15 +1236,15 @@ 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; + static cpumask_t tmp; - for_each_cpu(i, &cqm_cpumask) { - if (phys_id == topology_physical_package_id(i)) - return; /* already got reader for this socket */ - } + cpumask_and(&tmp, &cqm_cpumask, topology_core_cpumask(cpu)); - cpumask_set_cpu(cpu, &cqm_cpumask); + /* + * Pick a reader if there isn't one already. + */ + if (cpumask_empty(&tmp)) + cpumask_set_cpu(cpu, &cqm_cpumask); } static void intel_cqm_cpu_prepare(unsigned int cpu) @@ -1262,7 +1262,7 @@ static void intel_cqm_cpu_prepare(unsigned int cpu) static void intel_cqm_cpu_exit(unsigned int cpu) { - int phys_id = topology_physical_package_id(cpu); + static cpumask_t tmp; int i; /* @@ -1271,15 +1271,12 @@ static void intel_cqm_cpu_exit(unsigned int cpu) if (!cpumask_test_and_clear_cpu(cpu, &cqm_cpumask)) return; - for_each_online_cpu(i) { - if (i == cpu) - continue; + cpumask_and(&tmp, topology_core_cpumask(cpu), cpu_online_mask); + cpumask_clear_cpu(cpu, &tmp); + i = cpumask_any(&tmp); - if (phys_id == topology_physical_package_id(i)) { - cpumask_set_cpu(i, &cqm_cpumask); - break; - } - } + if (i < nr_cpu_ids) + cpumask_set_cpu(i, &cqm_cpumask); } static int intel_cqm_cpu_notifier(struct notifier_block *nb, -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/