From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755933AbbGFQyR (ORCPT ); Mon, 6 Jul 2015 12:54:17 -0400 Received: from mail-wg0-f43.google.com ([74.125.82.43]:35122 "EHLO mail-wg0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754976AbbGFQyM (ORCPT ); Mon, 6 Jul 2015 12:54:12 -0400 Date: Mon, 6 Jul 2015 18:54:07 +0200 From: Frederic Weisbecker To: Vatika Harlalka , Peter Zijlstra , Thomas Gleixner Cc: preeti@linux.vnet.ibm.com, mingo@redhat.com, rafael.j.wysocki@intel.com, schwidefsky@de.ibm.com, paulmck@linux.vnet.ibm.com, linux-kernel@vger.kernel.org, cl@linux.com, cmetcalf@ezchip.com, bitbucket@online.de Subject: Re: [PATCH RESEND] nohz: Affining unpinned timers Message-ID: <20150706165405.GD4981@lerouge> References: <20150623083133.GA587@vatika-Inspiron-3443> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150623083133.GA587@vatika-Inspiron-3443> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org I hope everybody received the patch because there is a ";" after each address :-) On Tue, Jun 23, 2015 at 02:01:33PM +0530, Vatika Harlalka wrote: > The problem addressed in this patch is about affining unpinned timers. > Adaptive or Full Dynticks CPUs should not be 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 FULL_NOHZ configured systems. It will not bring about functional > changes if NOHZ_FULL is not configured, because is_housekeeping_cpu() > always returns true in CONFIG_NO_HZ_FULL=n. > > Signed-off by: Vatika Harlalka The patch looks good to me. Peter, Thomas, are you ok with it too? Thanks. > --- > Changes: Patch sent to the right recipients. > > include/linux/tick.h | 9 ++++++++- > kernel/sched/core.c | 9 +++++++-- > 2 files changed, 15 insertions(+), 3 deletions(-) > > diff --git a/include/linux/tick.h b/include/linux/tick.h > index f8492da5..145bcba 100644 > --- a/include/linux/tick.h > +++ b/include/linux/tick.h > @@ -133,13 +133,20 @@ static inline bool tick_nohz_full_cpu(int cpu) > > return cpumask_test_cpu(cpu, 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_check(void) { } > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index 57bd333..acee856 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -599,18 +599,23 @@ int get_nohz_timer_target(int pinned) > int i; > struct sched_domain *sd; > > - if (pinned || !get_sysctl_timer_migration() || !idle_cpu(cpu)) > + if (pinned || !get_sysctl_timer_migration() || > + (!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; > -- > 2.4.2 >