From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752832Ab1HOP5T (ORCPT ); Mon, 15 Aug 2011 11:57:19 -0400 Received: from mail-qw0-f46.google.com ([209.85.216.46]:43560 "EHLO mail-qw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754852Ab1HOPxa (ORCPT ); Mon, 15 Aug 2011 11:53:30 -0400 From: Frederic Weisbecker To: LKML Cc: Frederic Weisbecker , Andrew Morton , Anton Blanchard , Avi Kivity , Ingo Molnar , Lai Jiangshan , "Paul E . McKenney" , Paul Menage , Peter Zijlstra , Stephen Hemminger , Thomas Gleixner , Tim Pepper Subject: [PATCH 15/32] nohz/cpuset: Restart tick when switching to idle task Date: Mon, 15 Aug 2011 17:52:12 +0200 Message-Id: <1313423549-27093-16-git-send-email-fweisbec@gmail.com> X-Mailer: git-send-email 1.7.5.4 In-Reply-To: <1313423549-27093-1-git-send-email-fweisbec@gmail.com> References: <1313423549-27093-1-git-send-email-fweisbec@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Ideally if we are in adaptive nohz mode and we switch to the the idle task, we shouldn't restart the tick since it's going to stop the tick soon anyway. That optimization requires some minor tweaks here and there though, lets handle that later. Signed-off-by: Frederic Weisbecker Cc: Andrew Morton Cc: Anton Blanchard Cc: Avi Kivity Cc: Ingo Molnar Cc: Lai Jiangshan Cc: Paul E . McKenney Cc: Paul Menage Cc: Peter Zijlstra Cc: Stephen Hemminger Cc: Thomas Gleixner Cc: Tim Pepper --- kernel/sched.c | 13 +++++++++++++ 1 files changed, 13 insertions(+), 0 deletions(-) diff --git a/kernel/sched.c b/kernel/sched.c index 353a66f..9b6b8eb 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -2477,6 +2477,18 @@ void cpuset_update_nohz(void) if (!cpuset_nohz_can_stop_tick()) cpuset_nohz_restart_tick(); } + +static void cpuset_nohz_task_switch(struct task_struct *next) +{ + int cpu = smp_processor_id(); + + if (tick_nohz_adaptive_mode() && next == idle_task(cpu)) + cpuset_nohz_restart_tick(); +} +#else +static void cpuset_nohz_task_switch(struct task_struct *next) +{ +} #endif static void @@ -3023,6 +3035,7 @@ static inline void prepare_task_switch(struct rq *rq, struct task_struct *prev, struct task_struct *next) { + cpuset_nohz_task_switch(next); sched_info_switch(prev, next); perf_event_task_sched_out(prev, next); fire_sched_out_preempt_notifiers(prev, next); -- 1.7.5.4