| Message ID | 1384504535-29987-1-git-send-email-tianyu.lan@intel.com (mailing list archive) |
|---|---|
| State | Rejected, archived |
| Headers | show |
On 15 November 2013 14:05, Lan Tianyu <tianyu.lan@intel.com> wrote: > 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 <tianyu.lan@intel.com> > --- > > 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(-) Acked-by: Viresh Kumar <viresh.kumar@linaro.org> -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Fri, 15 Nov 2013, Lan Tianyu wrote: > 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. What's the point of this? Checking for tick_nohz_enabled is wrong to begin with. See https://lkml.org/lkml/2013/11/13/424 -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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
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 <tianyu.lan@intel.com> --- 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(-)