From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754843AbbIBP6k (ORCPT ); Wed, 2 Sep 2015 11:58:40 -0400 Received: from terminus.zytor.com ([198.137.202.10]:52317 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752579AbbIBP6i (ORCPT ); Wed, 2 Sep 2015 11:58:38 -0400 Date: Wed, 2 Sep 2015 08:57:40 -0700 From: tip-bot for Vatika Harlalka Message-ID: Cc: mingo@kernel.org, tglx@linutronix.de, torvalds@linux-foundation.org, cmetcalf@ezchip.com, cl@linux.com, paulmck@linux.vnet.ibm.com, fweisbec@gmail.com, vatikaharlalka@gmail.com, preeti@linux.vnet.ibm.com, peterz@infradead.org, hpa@zytor.com, linux-kernel@vger.kernel.org Reply-To: paulmck@linux.vnet.ibm.com, cl@linux.com, cmetcalf@ezchip.com, torvalds@linux-foundation.org, tglx@linutronix.de, mingo@kernel.org, linux-kernel@vger.kernel.org, hpa@zytor.com, preeti@linux.vnet.ibm.com, peterz@infradead.org, vatikaharlalka@gmail.com, fweisbec@gmail.com In-Reply-To: <1441119060-2230-2-git-send-email-fweisbec@gmail.com> References: <1441119060-2230-2-git-send-email-fweisbec@gmail.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:sched/urgent] nohz: Affine unpinned timers to housekeepers Git-Commit-ID: 9642d18eee2cd169b60c6ac0f20bda745b5a3d1e 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: 9642d18eee2cd169b60c6ac0f20bda745b5a3d1e Gitweb: http://git.kernel.org/tip/9642d18eee2cd169b60c6ac0f20bda745b5a3d1e Author: Vatika Harlalka AuthorDate: Tue, 1 Sep 2015 16:50:59 +0200 Committer: Ingo Molnar CommitDate: Wed, 2 Sep 2015 10:33:22 +0200 nohz: Affine unpinned timers to housekeepers The problem addressed in this patch is about affining unpinned timers. Adaptive or Full Dynticks CPUs are currently disturbed by unnecessary jitter due to firing of such timers on them. This patch will affine timers to online CPUs which are not full dynticks in NOHZ_FULL configured systems. It should not introduce overhead in nohz full off case due to static keys. Signed-off-by: Vatika Harlalka Signed-off-by: Frederic Weisbecker Reviewed-by: Preeti U Murthy Acked-by: Thomas Gleixner Cc: Chris Metcalf Cc: Christoph Lameter Cc: Linus Torvalds Cc: Paul E. McKenney Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/1441119060-2230-2-git-send-email-fweisbec@gmail.com Signed-off-by: Ingo Molnar --- include/linux/tick.h | 9 +++++++++ kernel/sched/core.c | 7 +++++-- 2 files changed, 14 insertions(+), 2 deletions(-) diff --git a/include/linux/tick.h b/include/linux/tick.h index 48d901f..e312219 100644 --- a/include/linux/tick.h +++ b/include/linux/tick.h @@ -147,11 +147,20 @@ static inline void tick_nohz_full_add_cpus_to(struct cpumask *mask) cpumask_or(mask, mask, tick_nohz_full_mask); } +static inline int housekeeping_any_cpu(void) +{ + return cpumask_any_and(housekeeping_mask, cpu_online_mask); +} + extern void tick_nohz_full_kick(void); extern void tick_nohz_full_kick_cpu(int cpu); extern void tick_nohz_full_kick_all(void); extern void __tick_nohz_task_switch(void); #else +static inline int housekeeping_any_cpu(void) +{ + return smp_processor_id(); +} static inline bool tick_nohz_full_enabled(void) { return false; } static inline bool tick_nohz_full_cpu(int cpu) { return false; } static inline void tick_nohz_full_add_cpus_to(struct cpumask *mask) { } diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 8b864ec..0902e4d 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -623,18 +623,21 @@ int get_nohz_timer_target(void) int i, cpu = smp_processor_id(); struct sched_domain *sd; - if (!idle_cpu(cpu)) + if (!idle_cpu(cpu) && is_housekeeping_cpu(cpu)) return cpu; rcu_read_lock(); for_each_domain(cpu, sd) { for_each_cpu(i, sched_domain_span(sd)) { - if (!idle_cpu(i)) { + if (!idle_cpu(i) && is_housekeeping_cpu(cpu)) { cpu = i; goto unlock; } } } + + if (!is_housekeeping_cpu(cpu)) + cpu = housekeeping_any_cpu(); unlock: rcu_read_unlock(); return cpu;