From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933336Ab0HLALh (ORCPT ); Wed, 11 Aug 2010 20:11:37 -0400 Received: from kroah.org ([198.145.64.141]:47954 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933172Ab0HLAI6 (ORCPT ); Wed, 11 Aug 2010 20:08:58 -0400 X-Mailbox-Line: From gregkh@clark.site Wed Aug 11 17:06:18 2010 Message-Id: <20100812000618.032248444@clark.site> User-Agent: quilt/0.48-11.2 Date: Wed, 11 Aug 2010 17:06:13 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Peter Zijlstra , Mike Galbraith , Arjan van de Ven , Ingo Molnar Subject: [58/67] sched: Revert nohz_ratelimit() for now In-Reply-To: <20100812000641.GA6348@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.35-stable review patch. If anyone has any objections, please let us know. ------------------ From: Peter Zijlstra commit 396e894d289d69bacf5acd983c97cd6e21a14c08 upstream. Norbert reported that nohz_ratelimit() causes his laptop to burn about 4W (40%) extra. For now back out the change and see if we can adjust the power management code to make better decisions. Reported-by: Norbert Preining Signed-off-by: Peter Zijlstra Acked-by: Mike Galbraith Cc: Arjan van de Ven LKML-Reference: Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- include/linux/sched.h | 6 ------ kernel/sched.c | 10 ---------- kernel/time/tick-sched.c | 2 +- 3 files changed, 1 insertion(+), 17 deletions(-) --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -274,17 +274,11 @@ extern cpumask_var_t nohz_cpu_mask; #if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ) extern int select_nohz_load_balancer(int cpu); extern int get_nohz_load_balancer(void); -extern int nohz_ratelimit(int cpu); #else static inline int select_nohz_load_balancer(int cpu) { return 0; } - -static inline int nohz_ratelimit(int cpu) -{ - return 0; -} #endif /* --- a/kernel/sched.c +++ b/kernel/sched.c @@ -1232,16 +1232,6 @@ void wake_up_idle_cpu(int cpu) smp_send_reschedule(cpu); } -int nohz_ratelimit(int cpu) -{ - struct rq *rq = cpu_rq(cpu); - u64 diff = rq->clock - rq->nohz_stamp; - - rq->nohz_stamp = rq->clock; - - return diff < (NSEC_PER_SEC / HZ) >> 1; -} - #endif /* CONFIG_NO_HZ */ static u64 sched_avg_period(void) --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -325,7 +325,7 @@ void tick_nohz_stop_sched_tick(int inidl } while (read_seqretry(&xtime_lock, seq)); if (rcu_needs_cpu(cpu) || printk_needs_cpu(cpu) || - arch_needs_cpu(cpu) || nohz_ratelimit(cpu)) { + arch_needs_cpu(cpu)) { next_jiffies = last_jiffies + 1; delta_jiffies = 1; } else {