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cpuidle: teo: Replace time_span_ns with a flag

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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: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Christian Loehle <christian.loehle@arm.com>
Tested-by: Aboorva Devarajan <aboorvad@linux.ibm.com>
Tested-by: Christian Loehle <christian.loehle@arm.com>
Link: https://patch.msgid.link/6010475.MhkbZ0Pkbq@rjwysocki.net
This commit is contained in:
Rafael J. Wysocki 2025-01-13 19:51:59 +01:00
parent ddcfa79646
commit 65e18e6544
1 changed files with 9 additions and 18 deletions
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27
drivers/cpuidle/governors/teo.c
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@ -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;
}
}