Re: [PATCH] PM: cpuidle/suspend: Add s2idle usage and time state attributes

[Rafael J. Wysocki]

On Wednesday, March 14, 2018 12:27:21 PM CET Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> 
> Add a new attribute group called "s2idle" under the sysfs directory
> of each cpuidle state that supports the ->enter_s2idle callback
> and put two new attributes, "usage" and "time", into that group to
> represent the number of times the given state was requested for
> suspend-to-idle and the total time spent in suspend-to-idle after
> requesting that state, respectively.
> 
> That will allow diagnostic information related to suspend-to-idle
> to be collected without enabling advanced debug features and
> analyzing dmesg output.
> 
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>

Assuming to objections or concerns and queuing up.

> ---
>  Documentation/ABI/testing/sysfs-devices-system-cpu |   25 +++++++++
>  drivers/cpuidle/cpuidle.c                          |    9 +++
>  drivers/cpuidle/sysfs.c                            |   54 +++++++++++++++++++++
>  include/linux/cpuidle.h                            |    4 +
>  4 files changed, 92 insertions(+)
> 
> Index: linux-pm/drivers/cpuidle/sysfs.c
> ===================================================================
> --- linux-pm.orig/drivers/cpuidle/sysfs.c
> +++ linux-pm/drivers/cpuidle/sysfs.c
> @@ -330,6 +330,58 @@ struct cpuidle_state_kobj {
>  	struct kobject kobj;
>  };
>  
> +#ifdef CONFIG_SUSPEND
> +#define define_show_state_s2idle_ull_function(_name) \
> +static ssize_t show_state_s2idle_##_name(struct cpuidle_state *state, \
> +					 struct cpuidle_state_usage *state_usage, \
> +					 char *buf)				\
> +{ \
> +	return sprintf(buf, "%llu\n", state_usage->s2idle_##_name);\
> +}
> +
> +define_show_state_s2idle_ull_function(usage);
> +define_show_state_s2idle_ull_function(time);
> +
> +#define define_one_state_s2idle_ro(_name, show) \
> +static struct cpuidle_state_attr attr_s2idle_##_name = \
> +	__ATTR(_name, 0444, show, NULL)
> +
> +define_one_state_s2idle_ro(usage, show_state_s2idle_usage);
> +define_one_state_s2idle_ro(time, show_state_s2idle_time);
> +
> +static struct attribute *cpuidle_state_s2idle_attrs[] = {
> +	&attr_s2idle_usage.attr,
> +	&attr_s2idle_time.attr,
> +	NULL
> +};
> +
> +static const struct attribute_group cpuidle_state_s2idle_group = {
> +	.name	= "s2idle",
> +	.attrs	= cpuidle_state_s2idle_attrs,
> +};
> +
> +static void cpuidle_add_s2idle_attr_group(struct cpuidle_state_kobj *kobj)
> +{
> +	int ret;
> +
> +	if (!kobj->state->enter_s2idle)
> +		return;
> +
> +	ret = sysfs_create_group(&kobj->kobj, &cpuidle_state_s2idle_group);
> +	if (ret)
> +		pr_debug("%s: sysfs attribute group not created\n", __func__);
> +}
> +
> +static void cpuidle_remove_s2idle_attr_group(struct cpuidle_state_kobj *kobj)
> +{
> +	if (kobj->state->enter_s2idle)
> +		sysfs_remove_group(&kobj->kobj, &cpuidle_state_s2idle_group);
> +}
> +#else
> +static inline void cpuidle_add_s2idle_attr_group(struct cpuidle_state_kobj *kobj) { }
> +static inline void cpuidle_remove_s2idle_attr_group(struct cpuidle_state_kobj *kobj) { }
> +#endif /* CONFIG_SUSPEND */
> +
>  #define kobj_to_state_obj(k) container_of(k, struct cpuidle_state_kobj, kobj)
>  #define kobj_to_state(k) (kobj_to_state_obj(k)->state)
>  #define kobj_to_state_usage(k) (kobj_to_state_obj(k)->state_usage)
> @@ -383,6 +435,7 @@ static struct kobj_type ktype_state_cpui
>  
>  static inline void cpuidle_free_state_kobj(struct cpuidle_device *device, int i)
>  {
> +	cpuidle_remove_s2idle_attr_group(device->kobjs[i]);
>  	kobject_put(&device->kobjs[i]->kobj);
>  	wait_for_completion(&device->kobjs[i]->kobj_unregister);
>  	kfree(device->kobjs[i]);
> @@ -417,6 +470,7 @@ static int cpuidle_add_state_sysfs(struc
>  			kfree(kobj);
>  			goto error_state;
>  		}
> +		cpuidle_add_s2idle_attr_group(kobj);
>  		kobject_uevent(&kobj->kobj, KOBJ_ADD);
>  		device->kobjs[i] = kobj;
>  	}
> Index: linux-pm/include/linux/cpuidle.h
> ===================================================================
> --- linux-pm.orig/include/linux/cpuidle.h
> +++ linux-pm/include/linux/cpuidle.h
> @@ -33,6 +33,10 @@ struct cpuidle_state_usage {
>  	unsigned long long	disable;
>  	unsigned long long	usage;
>  	unsigned long long	time; /* in US */
> +#ifdef CONFIG_SUSPEND
> +	unsigned long long	s2idle_usage;
> +	unsigned long long	s2idle_time; /* in US */
> +#endif
>  };
>  
>  struct cpuidle_state {
> Index: linux-pm/drivers/cpuidle/cpuidle.c
> ===================================================================
> --- linux-pm.orig/drivers/cpuidle/cpuidle.c
> +++ linux-pm/drivers/cpuidle/cpuidle.c
> @@ -131,6 +131,10 @@ int cpuidle_find_deepest_state(struct cp
>  static void enter_s2idle_proper(struct cpuidle_driver *drv,
>  				struct cpuidle_device *dev, int index)
>  {
> +	ktime_t time_start, time_end;
> +
> +	time_start = ns_to_ktime(local_clock());
> +
>  	/*
>  	 * trace_suspend_resume() called by tick_freeze() for the last CPU
>  	 * executing it contains RCU usage regarded as invalid in the idle
> @@ -152,6 +156,11 @@ static void enter_s2idle_proper(struct c
>  	 */
>  	RCU_NONIDLE(tick_unfreeze());
>  	start_critical_timings();
> +
> +	time_end = ns_to_ktime(local_clock());
> +
> +	dev->states_usage[index].s2idle_time += ktime_us_delta(time_end, time_start);
> +	dev->states_usage[index].s2idle_usage++;
>  }
>  
>  /**
> Index: linux-pm/Documentation/ABI/testing/sysfs-devices-system-cpu
> ===================================================================
> --- linux-pm.orig/Documentation/ABI/testing/sysfs-devices-system-cpu
> +++ linux-pm/Documentation/ABI/testing/sysfs-devices-system-cpu
> @@ -198,6 +198,31 @@ Description:
>  		time (in microseconds) this cpu should spend in this idle state
>  		to make the transition worth the effort.
>  
> +What:		/sys/devices/system/cpu/cpuX/cpuidle/stateN/s2idle/
> +Date:		March 2018
> +KernelVersion:	v4.17
> +Contact:	Linux power management list <linux-pm@xxxxxxxxxxxxxxx>
> +Description:
> +		Idle state usage statistics related to suspend-to-idle.
> +
> +		This attribute group is only present for states that can be
> +		used in suspend-to-idle with suspended timekeeping.
> +
> +What:		/sys/devices/system/cpu/cpuX/cpuidle/stateN/s2idle/time
> +Date:		March 2018
> +KernelVersion:	v4.17
> +Contact:	Linux power management list <linux-pm@xxxxxxxxxxxxxxx>
> +Description:
> +		Total time spent by the CPU in suspend-to-idle (with scheduler
> +		tick suspended) after requesting this state.
> +
> +What:		/sys/devices/system/cpu/cpuX/cpuidle/stateN/s2idle/usage
> +Date:		March 2018
> +KernelVersion:	v4.17
> +Contact:	Linux power management list <linux-pm@xxxxxxxxxxxxxxx>
> +Description:
> +		Total number of times this state has been requested by the CPU
> +		while entering suspend-to-idle.
>  
>  What:		/sys/devices/system/cpu/cpu#/cpufreq/*
>  Date:		pre-git history
> 
>