From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S945792AbdDTNcN (ORCPT ); Thu, 20 Apr 2017 09:32:13 -0400 Received: from terminus.zytor.com ([65.50.211.136]:36117 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S944803AbdDTNcL (ORCPT ); Thu, 20 Apr 2017 09:32:11 -0400 Date: Thu, 20 Apr 2017 06:30:52 -0700 From: tip-bot for Chen Yu Message-ID: Cc: hpa@zytor.com, mingo@kernel.org, yu.c.chen@intel.com, tglx@linutronix.de, lenb@kernel.orq, prarit@redhat.com, linux-kernel@vger.kernel.org, rjw@rjwysocki.net Reply-To: rjw@rjwysocki.net, linux-kernel@vger.kernel.org, prarit@redhat.com, tglx@linutronix.de, lenb@kernel.orq, yu.c.chen@intel.com, hpa@zytor.com, mingo@kernel.org In-Reply-To: <1492357410-510-1-git-send-email-yu.c.chen@intel.com> References: <1492357410-510-1-git-send-email-yu.c.chen@intel.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/irq] x86/irq: Optimize free vector check in the CPU offline path Git-Commit-ID: c0edbd4a1693600d6eb9e2faad452638c35391f7 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: c0edbd4a1693600d6eb9e2faad452638c35391f7 Gitweb: http://git.kernel.org/tip/c0edbd4a1693600d6eb9e2faad452638c35391f7 Author: Chen Yu AuthorDate: Sun, 16 Apr 2017 23:43:30 +0800 Committer: Thomas Gleixner CommitDate: Thu, 20 Apr 2017 15:25:09 +0200 x86/irq: Optimize free vector check in the CPU offline path Before offlining a CPU its required to check whether there are enough free irq vectors available so interrupts can be migrated away from the CPU. This check is executed whether its required or not and neither stops searching when the number of required free vectors are reached. Bypass the free vector check if the current CPU has no irq to migrate and leave the for_each_online_cpu() loop when the free vector count reaches the number of required vectors. Suggested-by: Thomas Gleixner Signed-off-by: Chen Yu Cc: Prarit Bhargava Cc: Len Brown Cc: "Rafael J. Wysocki" Link: http://lkml.kernel.org/r/1492357410-510-1-git-send-email-yu.c.chen@intel.com Signed-off-by: Thomas Gleixner --- arch/x86/kernel/irq.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c index 4d8183b..f34fe74 100644 --- a/arch/x86/kernel/irq.c +++ b/arch/x86/kernel/irq.c @@ -394,6 +394,9 @@ int check_irq_vectors_for_cpu_disable(void) !cpumask_subset(&affinity_new, &online_new)) this_count++; } + /* No need to check any further. */ + if (!this_count) + return 0; count = 0; for_each_online_cpu(cpu) { @@ -411,8 +414,10 @@ int check_irq_vectors_for_cpu_disable(void) for (vector = FIRST_EXTERNAL_VECTOR; vector < first_system_vector; vector++) { if (!test_bit(vector, used_vectors) && - IS_ERR_OR_NULL(per_cpu(vector_irq, cpu)[vector])) - count++; + IS_ERR_OR_NULL(per_cpu(vector_irq, cpu)[vector])) { + if (++count == this_count) + return 0; + } } }