* [PATCH 2/2] Cpufreq/gov: use tick_nohz_check() to check idle micro accouting support [not found] <1383036537-30362-1-git-send-email-tianyu.lan@intel.com> @ 2013-10-29 8:48 ` Lan Tianyu 2013-11-15 8:35 ` [PATCH V2 1/2] Tick: Introduce tick_nohz_check() to check nohz enable status Lan Tianyu 1 sibling, 0 replies; 6+ messages in thread From: Lan Tianyu @ 2013-10-29 8:48 UTC (permalink / raw) To: rjw, viresh.kumar; +Cc: Lan Tianyu, cpufreq, linux-pm, linux-kernel Current, od_init() uses get_cpu_idle_time_us() to check whether idle micro accouting is supported. The get_cpu_idle_time_us() returns -1 only when tick nohz is disabled. This patch is to use tick_nohz_check() directly to check nohz enable status instead of get_cpu_idle_time_us(). This can avoid unnecessary getting and putting cpu. Signed-off-by: Lan Tianyu <tianyu.lan@intel.com> --- drivers/cpufreq/cpufreq_ondemand.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c index 32f26f6..79986a9 100644 --- a/drivers/cpufreq/cpufreq_ondemand.c +++ b/drivers/cpufreq/cpufreq_ondemand.c @@ -485,10 +485,7 @@ static int od_init(struct dbs_data *dbs_data) return -ENOMEM; } - cpu = get_cpu(); - idle_time = get_cpu_idle_time_us(cpu, NULL); - put_cpu(); - if (idle_time != -1ULL) { + if (tick_nohz_check()) { /* Idle micro accounting is supported. Use finer thresholds */ tuners->up_threshold = MICRO_FREQUENCY_UP_THRESHOLD; /* -- 1.8.4.rc0.1.g8f6a3e5.dirty ^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH V2 1/2] Tick: Introduce tick_nohz_check() to check nohz enable status [not found] <1383036537-30362-1-git-send-email-tianyu.lan@intel.com> 2013-10-29 8:48 ` [PATCH 2/2] Cpufreq/gov: use tick_nohz_check() to check idle micro accouting support Lan Tianyu @ 2013-11-15 8:35 ` Lan Tianyu 2013-11-15 8:35 ` [PATCH V2 2/2] Cpufreq/gov: use tick_nohz_check() to check idle micro accouting support Lan Tianyu ` (2 more replies) 1 sibling, 3 replies; 6+ messages in thread From: Lan Tianyu @ 2013-11-15 8:35 UTC (permalink / raw) To: dipankar, paulmck, tglx, fweisbec, rjw, viresh.kumar, rostedt Cc: Lan Tianyu, cpufreq, linux-pm, linux-kernel 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(-) 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 -- 1.8.4.rc0.1.g8f6a3e5.dirty ^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH V2 2/2] Cpufreq/gov: use tick_nohz_check() to check idle micro accouting support 2013-11-15 8:35 ` [PATCH V2 1/2] Tick: Introduce tick_nohz_check() to check nohz enable status Lan Tianyu @ 2013-11-15 8:35 ` Lan Tianyu 2013-11-15 10:36 ` Viresh Kumar 2013-11-15 10:35 ` [PATCH V2 1/2] Tick: Introduce tick_nohz_check() to check nohz enable status Viresh Kumar 2013-11-15 11:06 ` Thomas Gleixner 2 siblings, 1 reply; 6+ messages in thread From: Lan Tianyu @ 2013-11-15 8:35 UTC (permalink / raw) To: rjw, viresh.kumar; +Cc: Lan Tianyu, cpufreq, linux-pm, linux-kernel Current, od_init() uses get_cpu_idle_time_us() to check whether idle micro accouting is supported. The get_cpu_idle_time_us() returns -1 only when tick nohz is disabled. This patch is to use tick_nohz_check() directly to check nohz enable status instead of get_cpu_idle_time_us(). This can avoid unnecessary getting and putting cpu. Signed-off-by: Lan Tianyu <tianyu.lan@intel.com> --- drivers/cpufreq/cpufreq_ondemand.c | 7 +------ 1 file changed, 1 insertion(+), 6 deletions(-) diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c index 18d4091..7db2468 100644 --- a/drivers/cpufreq/cpufreq_ondemand.c +++ b/drivers/cpufreq/cpufreq_ondemand.c @@ -475,8 +475,6 @@ static struct attribute_group od_attr_group_gov_pol = { static int od_init(struct dbs_data *dbs_data) { struct od_dbs_tuners *tuners; - u64 idle_time; - int cpu; tuners = kzalloc(sizeof(*tuners), GFP_KERNEL); if (!tuners) { @@ -484,10 +482,7 @@ static int od_init(struct dbs_data *dbs_data) return -ENOMEM; } - cpu = get_cpu(); - idle_time = get_cpu_idle_time_us(cpu, NULL); - put_cpu(); - if (idle_time != -1ULL) { + if (tick_nohz_check()) { /* Idle micro accounting is supported. Use finer thresholds */ tuners->up_threshold = MICRO_FREQUENCY_UP_THRESHOLD; /* -- 1.8.4.rc0.1.g8f6a3e5.dirty ^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH V2 2/2] Cpufreq/gov: use tick_nohz_check() to check idle micro accouting support 2013-11-15 8:35 ` [PATCH V2 2/2] Cpufreq/gov: use tick_nohz_check() to check idle micro accouting support Lan Tianyu @ 2013-11-15 10:36 ` Viresh Kumar 0 siblings, 0 replies; 6+ messages in thread From: Viresh Kumar @ 2013-11-15 10:36 UTC (permalink / raw) To: Lan Tianyu Cc: Rafael J. Wysocki, cpufreq@vger.kernel.org, linux-pm@vger.kernel.org, Linux Kernel Mailing List On 15 November 2013 14:05, Lan Tianyu <tianyu.lan@intel.com> wrote: > Current, od_init() uses get_cpu_idle_time_us() to check whether > idle micro accouting is supported. The get_cpu_idle_time_us() > returns -1 only when tick nohz is disabled. This patch is to use > tick_nohz_check() directly to check nohz enable status instead of > get_cpu_idle_time_us(). This can avoid unnecessary getting and > putting cpu. > > Signed-off-by: Lan Tianyu <tianyu.lan@intel.com> > --- > drivers/cpufreq/cpufreq_ondemand.c | 7 +------ > 1 file changed, 1 insertion(+), 6 deletions(-) Acked-by: Viresh Kumar <viresh.kumar@linaro.org> ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH V2 1/2] Tick: Introduce tick_nohz_check() to check nohz enable status 2013-11-15 8:35 ` [PATCH V2 1/2] Tick: Introduce tick_nohz_check() to check nohz enable status Lan Tianyu 2013-11-15 8:35 ` [PATCH V2 2/2] Cpufreq/gov: use tick_nohz_check() to check idle micro accouting support Lan Tianyu @ 2013-11-15 10:35 ` Viresh Kumar 2013-11-15 11:06 ` Thomas Gleixner 2 siblings, 0 replies; 6+ messages in thread From: Viresh Kumar @ 2013-11-15 10:35 UTC (permalink / raw) To: Lan Tianyu Cc: dipankar, Paul McKenney, Thomas Gleixner, Frédéric Weisbecker, Rafael J. Wysocki, Steven Rostedt, cpufreq@vger.kernel.org, linux-pm@vger.kernel.org, Linux Kernel Mailing List 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> ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH V2 1/2] Tick: Introduce tick_nohz_check() to check nohz enable status 2013-11-15 8:35 ` [PATCH V2 1/2] Tick: Introduce tick_nohz_check() to check nohz enable status Lan Tianyu 2013-11-15 8:35 ` [PATCH V2 2/2] Cpufreq/gov: use tick_nohz_check() to check idle micro accouting support Lan Tianyu 2013-11-15 10:35 ` [PATCH V2 1/2] Tick: Introduce tick_nohz_check() to check nohz enable status Viresh Kumar @ 2013-11-15 11:06 ` Thomas Gleixner 2 siblings, 0 replies; 6+ messages in thread From: Thomas Gleixner @ 2013-11-15 11:06 UTC (permalink / raw) To: Lan Tianyu Cc: dipankar, paulmck, fweisbec, rjw, viresh.kumar, rostedt, cpufreq, linux-pm, linux-kernel 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 ^ permalink raw reply [flat|nested] 6+ messages in thread
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[not found] <1383036537-30362-1-git-send-email-tianyu.lan@intel.com>
2013-10-29 8:48 ` [PATCH 2/2] Cpufreq/gov: use tick_nohz_check() to check idle micro accouting support Lan Tianyu
2013-11-15 8:35 ` [PATCH V2 1/2] Tick: Introduce tick_nohz_check() to check nohz enable status Lan Tianyu
2013-11-15 8:35 ` [PATCH V2 2/2] Cpufreq/gov: use tick_nohz_check() to check idle micro accouting support Lan Tianyu
2013-11-15 10:36 ` Viresh Kumar
2013-11-15 10:35 ` [PATCH V2 1/2] Tick: Introduce tick_nohz_check() to check nohz enable status Viresh Kumar
2013-11-15 11:06 ` Thomas Gleixner
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