| Message ID | 20191030075141.1039-1-daniel.lezcano@linaro.org |
|---|---|
| State | New |
| Headers | show |
| Series | [V6,1/3] cpuidle: play_idle: Make play_idle more flexible | expand |
On Wednesday, October 30, 2019 8:51:39 AM CET Daniel Lezcano wrote: > The play_idle function has two users, the intel powerclamp and the > idle_injection. > > The idle injection cooling device uses the function via the > idle_injection powercap's APIs. Unfortunately, play_idle is currently > limited by the idle state depth: by default the deepest idle state is > selected. On the ARM[64] platforms, most of the time it is the cluster > idle state, the exit latency and the residency can be very high. That > reduces the scope of the idle injection usage because the impact on > the performances can be very significant. > > If the idle injection cycles can be done with a shallow state like a > retention state, the cooling effect would eventually give similar > results than the cpufreq cooling device. > > In order to prepare the function to receive an idle state parameter, > let's replace the 'use_deepest_state' boolean field with 'use_state' > and use this value to enter the specific idle state. > > The current code keeps the default behavior which is go to the deepest > idle state. > > Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org> > Acked-by: Mathieu Poirier <mathieu.poirier@linaro.org> > Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org> > --- > V6: > - Change use_state variable name by use_state_idx: > https://lkml.org/lkml/2019/10/28/874 > V5: > - Fix s2idle default idle state value: > https://lkml.org/lkml/2019/10/15/522 > --- > drivers/cpuidle/cpuidle.c | 21 +++++++++++---------- > include/linux/cpuidle.h | 13 ++++++------- > kernel/sched/idle.c | 11 +++++++---- > 3 files changed, 24 insertions(+), 21 deletions(-) > > diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c > index 0895b988fa92..18523ea6b11b 100644 > --- a/drivers/cpuidle/cpuidle.c > +++ b/drivers/cpuidle/cpuidle.c > @@ -99,31 +99,31 @@ static int find_deepest_state(struct cpuidle_driver *drv, > } > > /** > - * cpuidle_use_deepest_state - Set/clear governor override flag. > - * @enable: New value of the flag. > + * cpuidle_use_state - Force the cpuidle framework to enter an idle state. > + * @state: An integer for an idle state > * > - * Set/unset the current CPU to use the deepest idle state (override governors > - * going forward if set). > + * Specify an idle state the cpuidle framework must step in and bypass > + * the idle state selection process. > */ > -void cpuidle_use_deepest_state(bool enable) > +void cpuidle_use_state(int index) > { > struct cpuidle_device *dev; > > preempt_disable(); > dev = cpuidle_get_device(); > if (dev) > - dev->use_deepest_state = enable; > + dev->use_state_idx = index; > preempt_enable(); > } > > /** > * cpuidle_find_deepest_state - Find the deepest available idle state. > - * @drv: cpuidle driver for the given CPU. > - * @dev: cpuidle device for the given CPU. > */ > -int cpuidle_find_deepest_state(struct cpuidle_driver *drv, > - struct cpuidle_device *dev) > +int cpuidle_find_deepest_state(void) > { > + struct cpuidle_device *dev = cpuidle_get_device(); > + struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev); This is totally wasteful for the cpuidle_idle_call() use case. > + > return find_deepest_state(drv, dev, UINT_MAX, 0, false); > } > > @@ -554,6 +554,7 @@ static void __cpuidle_unregister_device(struct cpuidle_device *dev) > static void __cpuidle_device_init(struct cpuidle_device *dev) > { > memset(dev->states_usage, 0, sizeof(dev->states_usage)); > + dev->use_state_idx = CPUIDLE_STATE_NOUSE; > dev->last_residency = 0; > dev->next_hrtimer = 0; > } > diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h > index 4b6b5bea8f79..d53ad36cb2de 100644 > --- a/include/linux/cpuidle.h > +++ b/include/linux/cpuidle.h > @@ -15,6 +15,7 @@ > #include <linux/list.h> > #include <linux/hrtimer.h> > > +#define CPUIDLE_STATE_NOUSE -1 > #define CPUIDLE_STATE_MAX 10 > #define CPUIDLE_NAME_LEN 16 > #define CPUIDLE_DESC_LEN 32 > @@ -80,11 +81,11 @@ struct cpuidle_driver_kobj; > struct cpuidle_device { > unsigned int registered:1; > unsigned int enabled:1; > - unsigned int use_deepest_state:1; > unsigned int poll_time_limit:1; > unsigned int cpu; > ktime_t next_hrtimer; > > + int use_state_idx; > int last_state_idx; > int last_residency; > u64 poll_limit_ns; > @@ -203,19 +204,17 @@ static inline struct cpuidle_device *cpuidle_get_device(void) {return NULL; } > #endif > > #ifdef CONFIG_CPU_IDLE > -extern int cpuidle_find_deepest_state(struct cpuidle_driver *drv, > - struct cpuidle_device *dev); > +extern int cpuidle_find_deepest_state(void); > extern int cpuidle_enter_s2idle(struct cpuidle_driver *drv, > struct cpuidle_device *dev); > -extern void cpuidle_use_deepest_state(bool enable); > +extern void cpuidle_use_state(int index); > #else > -static inline int cpuidle_find_deepest_state(struct cpuidle_driver *drv, > - struct cpuidle_device *dev) > +static inline int cpuidle_find_deepest_state(void) > {return -ENODEV; } > static inline int cpuidle_enter_s2idle(struct cpuidle_driver *drv, > struct cpuidle_device *dev) > {return -ENODEV; } > -static inline void cpuidle_use_deepest_state(bool enable) > +static inline void cpuidle_use_state(int index) > { > } > #endif > diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c > index 8dad5aa600ea..fb9fc93f1497 100644 > --- a/kernel/sched/idle.c > +++ b/kernel/sched/idle.c > @@ -165,7 +165,8 @@ static void cpuidle_idle_call(void) > * until a proper wakeup interrupt happens. > */ > > - if (idle_should_enter_s2idle() || dev->use_deepest_state) { > + if (idle_should_enter_s2idle() || > + dev->use_state_idx != CPUIDLE_STATE_NOUSE) { > if (idle_should_enter_s2idle()) { > rcu_idle_enter(); > > @@ -176,12 +177,14 @@ static void cpuidle_idle_call(void) > } > > rcu_idle_exit(); > + next_state = cpuidle_find_deepest_state(); > + } else { > + next_state = dev->use_state_idx; > } > > tick_nohz_idle_stop_tick(); > rcu_idle_enter(); > > - next_state = cpuidle_find_deepest_state(drv, dev); > call_cpuidle(drv, dev, next_state); > } else { > bool stop_tick = true; > @@ -328,7 +331,7 @@ void play_idle(unsigned long duration_us) > rcu_sleep_check(); > preempt_disable(); > current->flags |= PF_IDLE; > - cpuidle_use_deepest_state(true); > + cpuidle_use_state(cpuidle_find_deepest_state()); And this assumes that the deepest state will not change for the whole play_idle() duration, but what if it is disabled by user space in the meantime? > > it.done = 0; > hrtimer_init_on_stack(&it.timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); > @@ -339,7 +342,7 @@ void play_idle(unsigned long duration_us) > while (!READ_ONCE(it.done)) > do_idle(); > > - cpuidle_use_deepest_state(false); > + cpuidle_use_state(CPUIDLE_STATE_NOUSE); > current->flags &= ~PF_IDLE; > > preempt_fold_need_resched(); >
diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c index 0895b988fa92..18523ea6b11b 100644 --- a/drivers/cpuidle/cpuidle.c +++ b/drivers/cpuidle/cpuidle.c @@ -99,31 +99,31 @@ static int find_deepest_state(struct cpuidle_driver *drv, } /** - * cpuidle_use_deepest_state - Set/clear governor override flag. - * @enable: New value of the flag. + * cpuidle_use_state - Force the cpuidle framework to enter an idle state. + * @state: An integer for an idle state * - * Set/unset the current CPU to use the deepest idle state (override governors - * going forward if set). + * Specify an idle state the cpuidle framework must step in and bypass + * the idle state selection process. */ -void cpuidle_use_deepest_state(bool enable) +void cpuidle_use_state(int index) { struct cpuidle_device *dev; preempt_disable(); dev = cpuidle_get_device(); if (dev) - dev->use_deepest_state = enable; + dev->use_state_idx = index; preempt_enable(); } /** * cpuidle_find_deepest_state - Find the deepest available idle state. - * @drv: cpuidle driver for the given CPU. - * @dev: cpuidle device for the given CPU. */ -int cpuidle_find_deepest_state(struct cpuidle_driver *drv, - struct cpuidle_device *dev) +int cpuidle_find_deepest_state(void) { + struct cpuidle_device *dev = cpuidle_get_device(); + struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev); + return find_deepest_state(drv, dev, UINT_MAX, 0, false); } @@ -554,6 +554,7 @@ static void __cpuidle_unregister_device(struct cpuidle_device *dev) static void __cpuidle_device_init(struct cpuidle_device *dev) { memset(dev->states_usage, 0, sizeof(dev->states_usage)); + dev->use_state_idx = CPUIDLE_STATE_NOUSE; dev->last_residency = 0; dev->next_hrtimer = 0; } diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h index 4b6b5bea8f79..d53ad36cb2de 100644 --- a/include/linux/cpuidle.h +++ b/include/linux/cpuidle.h @@ -15,6 +15,7 @@ #include <linux/list.h> #include <linux/hrtimer.h> +#define CPUIDLE_STATE_NOUSE -1 #define CPUIDLE_STATE_MAX 10 #define CPUIDLE_NAME_LEN 16 #define CPUIDLE_DESC_LEN 32 @@ -80,11 +81,11 @@ struct cpuidle_driver_kobj; struct cpuidle_device { unsigned int registered:1; unsigned int enabled:1; - unsigned int use_deepest_state:1; unsigned int poll_time_limit:1; unsigned int cpu; ktime_t next_hrtimer; + int use_state_idx; int last_state_idx; int last_residency; u64 poll_limit_ns; @@ -203,19 +204,17 @@ static inline struct cpuidle_device *cpuidle_get_device(void) {return NULL; } #endif #ifdef CONFIG_CPU_IDLE -extern int cpuidle_find_deepest_state(struct cpuidle_driver *drv, - struct cpuidle_device *dev); +extern int cpuidle_find_deepest_state(void); extern int cpuidle_enter_s2idle(struct cpuidle_driver *drv, struct cpuidle_device *dev); -extern void cpuidle_use_deepest_state(bool enable); +extern void cpuidle_use_state(int index); #else -static inline int cpuidle_find_deepest_state(struct cpuidle_driver *drv, - struct cpuidle_device *dev) +static inline int cpuidle_find_deepest_state(void) {return -ENODEV; } static inline int cpuidle_enter_s2idle(struct cpuidle_driver *drv, struct cpuidle_device *dev) {return -ENODEV; } -static inline void cpuidle_use_deepest_state(bool enable) +static inline void cpuidle_use_state(int index) { } #endif diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c index 8dad5aa600ea..fb9fc93f1497 100644 --- a/kernel/sched/idle.c +++ b/kernel/sched/idle.c @@ -165,7 +165,8 @@ static void cpuidle_idle_call(void) * until a proper wakeup interrupt happens. */ - if (idle_should_enter_s2idle() || dev->use_deepest_state) { + if (idle_should_enter_s2idle() || + dev->use_state_idx != CPUIDLE_STATE_NOUSE) { if (idle_should_enter_s2idle()) { rcu_idle_enter(); @@ -176,12 +177,14 @@ static void cpuidle_idle_call(void) } rcu_idle_exit(); + next_state = cpuidle_find_deepest_state(); + } else { + next_state = dev->use_state_idx; } tick_nohz_idle_stop_tick(); rcu_idle_enter(); - next_state = cpuidle_find_deepest_state(drv, dev); call_cpuidle(drv, dev, next_state); } else { bool stop_tick = true; @@ -328,7 +331,7 @@ void play_idle(unsigned long duration_us) rcu_sleep_check(); preempt_disable(); current->flags |= PF_IDLE; - cpuidle_use_deepest_state(true); + cpuidle_use_state(cpuidle_find_deepest_state()); it.done = 0; hrtimer_init_on_stack(&it.timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); @@ -339,7 +342,7 @@ void play_idle(unsigned long duration_us) while (!READ_ONCE(it.done)) do_idle(); - cpuidle_use_deepest_state(false); + cpuidle_use_state(CPUIDLE_STATE_NOUSE); current->flags &= ~PF_IDLE; preempt_fold_need_resched();