Commit 65e18e65 authored by Rafael J. Wysocki's avatar Rafael J. Wysocki
Browse files

cpuidle: teo: Replace time_span_ns with a flag 



After recent updates, the time_span_ns field in struct teo_cpu has
become an indicator on whether or not the most recent wakeup has been
"genuine" which may as well be indicated by a bool field without
calling local_clock(), so update the code accordingly.

No intentional functional impact.

Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: default avatarChristian Loehle <christian.loehle@arm.com>
Tested-by: default avatarAboorva Devarajan <aboorvad@linux.ibm.com>
Tested-by: default avatarChristian Loehle <christian.loehle@arm.com>
Link: https://patch.msgid.link/6010475.MhkbZ0Pkbq@rjwysocki.net
parent ddcfa796

drivers/cpuidle/governors/teo.c

+9 −18
Original line number Diff line number Diff line
@@ -124,20 +124,20 @@ struct teo_bin { 


/**

 * struct teo_cpu - CPU data used by the TEO cpuidle governor.

 * @time_span_ns: Time between idle state selection and post-wakeup update.

 * @sleep_length_ns: Time till the closest timer event (at the selection time).

 * @state_bins: Idle state data bins for this CPU.

 * @total: Grand total of the "intercepts" and "hits" metrics for all bins.

 * @tick_intercepts: "Intercepts" before TICK_NSEC.

 * @short_idles: Wakeups after short idle periods.

 * @artificial_wakeup: Set if the wakeup has been triggered by a safety net.

 */

struct teo_cpu {

	s64 time_span_ns;

	s64 sleep_length_ns;

	struct teo_bin state_bins[CPUIDLE_STATE_MAX];

	unsigned int total;

	unsigned int tick_intercepts;

	unsigned int short_idles;

	bool artificial_wakeup;

};



static DEFINE_PER_CPU(struct teo_cpu, teo_cpus);
@@ -156,7 +156,7 @@ static void teo_update(struct cpuidle_driver *drv, struct cpuidle_device *dev) 


	cpu_data->short_idles -= cpu_data->short_idles >> DECAY_SHIFT;



	if (cpu_data->time_span_ns < 0) {

	if (cpu_data->artificial_wakeup) {

		/*

		 * If one of the safety nets has triggered, assume that this

		 * might have been a long sleep.
@@ -165,13 +165,6 @@ static void teo_update(struct cpuidle_driver *drv, struct cpuidle_device *dev) 
	} else {

		u64 lat_ns = drv->states[dev->last_state_idx].exit_latency_ns;



		/*

		 * The computations below are to determine whether or not the

		 * (saved) time till the next timer event and the measured idle

		 * duration fall into the same "bin", so use last_residency_ns

		 * for that instead of time_span_ns which includes the cpuidle

		 * overhead.

		 */

		measured_ns = dev->last_residency_ns;

		/*

		 * The delay between the wakeup and the first instruction
@@ -286,7 +279,6 @@ static int teo_select(struct cpuidle_driver *drv, struct cpuidle_device *dev, 
		dev->last_state_idx = -1;

	}



	cpu_data->time_span_ns = local_clock();

	/*

	 * Set the sleep length to infinity in case the invocation of

	 * tick_nohz_get_sleep_length() below is skipped, in which case it won't
@@ -504,17 +496,16 @@ static void teo_reflect(struct cpuidle_device *dev, int state) 
	struct teo_cpu *cpu_data = per_cpu_ptr(&teo_cpus, dev->cpu);



	dev->last_state_idx = state;

	/*

	 * If the wakeup was not "natural", but triggered by one of the safety

	 * nets, assume that the CPU might have been idle for the entire sleep

	 * length time.

	 */

	if (dev->poll_time_limit ||

	    (tick_nohz_idle_got_tick() && cpu_data->sleep_length_ns > TICK_NSEC)) {

		/*

		 * The wakeup was not "genuine", but triggered by one of the

		 * safety nets.

		 */

		dev->poll_time_limit = false;

		cpu_data->time_span_ns = KTIME_MIN;

		cpu_data->artificial_wakeup = true;

	} else {

		cpu_data->time_span_ns = local_clock() - cpu_data->time_span_ns;

		cpu_data->artificial_wakeup = false;

	}

}