Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753350Ab3J2JAF (ORCPT ); Tue, 29 Oct 2013 05:00:05 -0400 Received: from mga14.intel.com ([143.182.124.37]:29849 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752824Ab3J2JAB (ORCPT ); Tue, 29 Oct 2013 05:00:01 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.93,535,1378882800"; d="scan'208";a="381557662" From: Lan Tianyu To: rjw@rjwysocki.net, viresh.kumar@linaro.org, dipankar@in.ibm.com, paulmck@linux.vnet.ibm.com, fweisbec@gmail.com, youquan.song@intel.com, riel@redhat.com Cc: Lan Tianyu , linux-kernel@vger.kernel.org Subject: [PATCH 1/2] Tick: Introduce tick_nohz_check() to check nohz enable status Date: Tue, 29 Oct 2013 16:48:56 +0800 Message-Id: <1383036537-30362-1-git-send-email-tianyu.lan@intel.com> X-Mailer: git-send-email 1.7.9.5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2958 Lines: 80 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 --- 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..d381a22 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 tick_nohz_enabled; +} +EXPORT_SYMBOL_GPL(tick_nohz_check); /* * Enable / Disable tickless mode -- 1.8.4.rc0.1.g8f6a3e5.dirty -- 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/