From patchwork Fri Nov 15 08:35:34 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "lan,Tianyu" X-Patchwork-Id: 3187191 Return-Path: X-Original-To: patchwork-linux-pm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 4CD839F3AE for ; Fri, 15 Nov 2013 08:47:08 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 42E0220174 for ; Fri, 15 Nov 2013 08:47:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 144B120134 for ; Fri, 15 Nov 2013 08:47:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752969Ab3KOIrE (ORCPT ); Fri, 15 Nov 2013 03:47:04 -0500 Received: from mga02.intel.com ([134.134.136.20]:64104 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752687Ab3KOIrC (ORCPT ); Fri, 15 Nov 2013 03:47:02 -0500 Received: from orsmga002.jf.intel.com ([10.7.209.21]) by orsmga101.jf.intel.com with ESMTP; 15 Nov 2013 00:47:02 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.93,535,1378882800"; d="scan'208";a="435692232" Received: from lantianyu-ws.sh.intel.com (HELO localhost) ([10.239.37.18]) by orsmga002.jf.intel.com with ESMTP; 15 Nov 2013 00:46:55 -0800 From: Lan Tianyu To: dipankar@in.ibm.com, paulmck@linux.vnet.ibm.com, tglx@linutronix.de, fweisbec@gmail.com, rjw@rjwysocki.net, viresh.kumar@linaro.org, rostedt@goodmis.org Cc: Lan Tianyu , cpufreq@vger.kernel.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH V2 1/2] Tick: Introduce tick_nohz_check() to check nohz enable status Date: Fri, 15 Nov 2013 16:35:34 +0800 Message-Id: <1384504535-29987-1-git-send-email-tianyu.lan@intel.com> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <1383036537-30362-1-git-send-email-tianyu.lan@intel.com> References: <1383036537-30362-1-git-send-email-tianyu.lan@intel.com> Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP In some cases, nohz enable status needs to be checked. E.G, in RCU and cpufreq ondemand governor. So add tick_nohz_check() to return tick_nohz_enabled value And use tick_nohz_check() instead of referencing tick_nohz_enabled in the rcutree_plugin.h. Signed-off-by: Lan Tianyu Acked-by: Viresh Kumar --- Change since V2: Add ACCESS_ONCE to tick_nohz_check(). include/linux/tick.h | 2 ++ kernel/rcutree_plugin.h | 4 +--- kernel/time/tick-sched.c | 8 +++++++- 3 files changed, 10 insertions(+), 4 deletions(-) diff --git a/include/linux/tick.h b/include/linux/tick.h index 5128d33..a9c5374 100644 --- a/include/linux/tick.h +++ b/include/linux/tick.h @@ -136,6 +136,7 @@ static inline int tick_nohz_tick_stopped(void) extern void tick_nohz_idle_enter(void); extern void tick_nohz_idle_exit(void); extern void tick_nohz_irq_exit(void); +extern int tick_nohz_check(void); extern ktime_t tick_nohz_get_sleep_length(void); extern u64 get_cpu_idle_time_us(int cpu, u64 *last_update_time); extern u64 get_cpu_iowait_time_us(int cpu, u64 *last_update_time); @@ -155,6 +156,7 @@ static inline ktime_t tick_nohz_get_sleep_length(void) return len; } +static inline int tick_nohz_check(void) { return 0; } static inline u64 get_cpu_idle_time_us(int cpu, u64 *unused) { return -1; } static inline u64 get_cpu_iowait_time_us(int cpu, u64 *unused) { return -1; } # endif /* !CONFIG_NO_HZ_COMMON */ diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h index 130c97b..af167ec 100644 --- a/kernel/rcutree_plugin.h +++ b/kernel/rcutree_plugin.h @@ -1627,8 +1627,6 @@ module_param(rcu_idle_gp_delay, int, 0644); static int rcu_idle_lazy_gp_delay = RCU_IDLE_LAZY_GP_DELAY; module_param(rcu_idle_lazy_gp_delay, int, 0644); -extern int tick_nohz_enabled; - /* * Try to advance callbacks for all flavors of RCU on the current CPU. * Afterwards, if there are any callbacks ready for immediate invocation, @@ -1718,7 +1716,7 @@ static void rcu_prepare_for_idle(int cpu) int tne; /* Handle nohz enablement switches conservatively. */ - tne = ACCESS_ONCE(tick_nohz_enabled); + tne = tick_nohz_check(); if (tne != rdtp->tick_nohz_enabled_snap) { if (rcu_cpu_has_callbacks(cpu, NULL)) invoke_rcu_core(); /* force nohz to see update. */ diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 3612fc7..a568845 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -361,7 +361,13 @@ void __init tick_nohz_init(void) /* * NO HZ enabled ? */ -int tick_nohz_enabled __read_mostly = 1; +static int tick_nohz_enabled __read_mostly = 1; + +int tick_nohz_check(void) +{ + return ACCESS_ONCE(tick_nohz_enabled); +} +EXPORT_SYMBOL_GPL(tick_nohz_check); /* * Enable / Disable tickless mode