Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754700AbbHNBqW (ORCPT ); Thu, 13 Aug 2015 21:46:22 -0400 Received: from mail-wi0-f181.google.com ([209.85.212.181]:34876 "EHLO mail-wi0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751952AbbHNBqV (ORCPT ); Thu, 13 Aug 2015 21:46:21 -0400 From: Frederic Weisbecker To: Peter Zijlstra , Ingo Molnar Cc: LKML , Vatika Harlalka , Chris Metcalf , Thomas Gleixner , Preeti U Murthy , Christoph Lameter , "Paul E . McKenney" , Frederic Weisbecker Subject: [PATCH RESEND] sched/nohz: Affine unpinned timers to housekeepers Date: Fri, 14 Aug 2015 03:46:14 +0200 Message-Id: <1439516774-4614-1-git-send-email-fweisbec@gmail.com> X-Mailer: git-send-email 2.1.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2849 Lines: 86 From: Vatika Harlalka 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. Reviewed-by: Preeti U Murthy Signed-off by: Vatika Harlalka Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Christoph Lameter Cc: Thomas Gleixner Cc: Paul E. McKenney Cc: Chris Metcalf Signed-off-by: Frederic Weisbecker --- include/linux/tick.h | 9 ++++++++- kernel/sched/core.c | 7 +++++-- 2 files changed, 13 insertions(+), 3 deletions(-) diff --git a/include/linux/tick.h b/include/linux/tick.h index 3741ba1..51e6493 100644 --- a/include/linux/tick.h +++ b/include/linux/tick.h @@ -143,13 +143,20 @@ static inline void tick_nohz_full_add_cpus_to(struct cpumask *mask) if (tick_nohz_full_enabled()) 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_check(void); 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(struct task_struct *tsk); #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 9917c96..4fd42e4 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; -- 2.1.4 -- 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/