Re: [patch 2/5] cpuidle: add get_poll_time callback

Rafael J. Wysocki
2019-06-25T21:52:23Z

On Fri, Jun 14, 2019 at 12:55 AM Marcelo Tosatti <mtosatti@redhat.com> wrote:
>
> Add a "get_poll_time" callback to the cpuidle_governor structure,
> and change poll state to poll for that amount of time.
>
> Provide a default method for it, while allowing individual governors
> to override it.
>
> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

Fair enough:

Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

>
> ---
> drivers/cpuidle/cpuidle.c | 40 ++++++++++++++++++++++++++++++++++++++++
> drivers/cpuidle/poll_state.c | 11 ++---------
> include/linux/cpuidle.h | 8 ++++++++
> 3 files changed, 50 insertions(+), 9 deletions(-)
>
> Index: linux-2.6.git/drivers/cpuidle/cpuidle.c
> ===================================================================
> --- linux-2.6.git.orig/drivers/cpuidle/cpuidle.c 2019-06-13 17:57:33.111185824 -0400
> +++ linux-2.6.git/drivers/cpuidle/cpuidle.c 2019-06-13 18:09:48.158500660 -0400
> @@ -362,6 +362,46 @@
> }
>
> /**
> + * cpuidle_default_poll_time - default routine used to return poll time
> + * governors can override it if necessary
> + *
> + * @drv: the cpuidle driver tied with the cpu
> + * @dev: the cpuidle device
> + *
> + */
> +static u64 cpuidle_default_poll_time(struct cpuidle_driver *drv,
> + struct cpuidle_device *dev)
> +{
> + int i;
> +
> + for (i = 1; i < drv->state_count; i++) {
> + if (drv->states[i].disabled || dev->states_usage[i].disable)
> + continue;
> +
> + return (u64)drv->states[i].target_residency * NSEC_PER_USEC;
> + }
> +
> + return TICK_NSEC;
> +}
> +
> +/**
> + * cpuidle_get_poll_time - tell the polling driver how much time to poll,
> + * in nanoseconds.
> + *
> + * @drv: the cpuidle driver tied with the cpu
> + * @dev: the cpuidle device
> + *
> + */
> +u64 cpuidle_get_poll_time(struct cpuidle_driver *drv,
> + struct cpuidle_device *dev)
> +{
> + if (cpuidle_curr_governor->get_poll_time)
> + return cpuidle_curr_governor->get_poll_time(drv, dev);
> +
> + return cpuidle_default_poll_time(drv, dev);
> +}
> +
> +/**
> * cpuidle_install_idle_handler - installs the cpuidle idle loop handler
> */
> void cpuidle_install_idle_handler(void)
> Index: linux-2.6.git/drivers/cpuidle/poll_state.c
> ===================================================================
> --- linux-2.6.git.orig/drivers/cpuidle/poll_state.c 2019-06-13 17:57:33.111185824 -0400
> +++ linux-2.6.git/drivers/cpuidle/poll_state.c 2019-06-13 18:01:19.846944820 -0400
> @@ -20,16 +20,9 @@
> local_irq_enable();
> if (!current_set_polling_and_test()) {
> unsigned int loop_count = 0;
> - u64 limit = TICK_NSEC;
> - int i;
> + u64 limit;
>
> - for (i = 1; i < drv->state_count; i++) {
> - if (drv->states[i].disabled || dev->states_usage[i].disable)
> - continue;
> -
> - limit = (u64)drv->states[i].target_residency * NSEC_PER_USEC;
> - break;
> - }
> + limit = cpuidle_get_poll_time(drv, dev);
>
> while (!need_resched()) {
> cpu_relax();
> Index: linux-2.6.git/include/linux/cpuidle.h
> ===================================================================
> --- linux-2.6.git.orig/include/linux/cpuidle.h 2019-06-13 17:57:33.111185824 -0400
> +++ linux-2.6.git/include/linux/cpuidle.h 2019-06-13 18:01:19.846944820 -0400
> @@ -132,6 +132,8 @@
> extern int cpuidle_enter(struct cpuidle_driver *drv,
> struct cpuidle_device *dev, int index);
> extern void cpuidle_reflect(struct cpuidle_device *dev, int index);
> +extern u64 cpuidle_get_poll_time(struct cpuidle_driver *drv,
> + struct cpuidle_device *dev);
>
> extern int cpuidle_register_driver(struct cpuidle_driver *drv);
> extern struct cpuidle_driver *cpuidle_get_driver(void);
> @@ -166,6 +168,9 @@
> struct cpuidle_device *dev, int index)
> {return -ENODEV; }
> static inline void cpuidle_reflect(struct cpuidle_device *dev, int index) { }
> +extern u64 cpuidle_get_poll_time(struct cpuidle_driver *drv,
> + struct cpuidle_device *dev)
> +{return 0; }
> static inline int cpuidle_register_driver(struct cpuidle_driver *drv)
> {return -ENODEV; }
> static inline struct cpuidle_driver *cpuidle_get_driver(void) {return NULL; }
> @@ -246,6 +251,9 @@
> struct cpuidle_device *dev,
> bool *stop_tick);
> void (*reflect) (struct cpuidle_device *dev, int index);
> +
> + u64 (*get_poll_time) (struct cpuidle_driver *drv,
> + struct cpuidle_device *dev);
> };
>
> #ifdef CONFIG_CPU_IDLE
>
>