Re: [Patch v4 2/6] sched: Add infrastructure to store and update instantaneous thermal pressure

Dietmar Eggemann
2019-11-01T12:17:37Z

On 22.10.19 22:34, Thara Gopinath wrote:

[...]

> +/**
> + * trigger_thermal_pressure_average: Trigger the thermal pressure accumulate
> + * and average algorithm
> + */
> +void trigger_thermal_pressure_average(struct rq *rq)
> +{
> + update_thermal_load_avg(rq_clock_task(rq), rq,
> + per_cpu(delta_capacity, cpu_of(rq)));
> +}

Why not call update_thermal_load_avg() directly in fair.c? We do this for all
the other update_foo_load_avg() functions (foo eq. irq, rt_rq, dl_rq ...)

You don't have to pass 'u64 now', so you can hide it plus the
sched_thermal_decay_coeff add-on within update_thermal_load_avg().
(Similar to update_irq_load_avg()).

You could even hide 'u64 capacity' in it.

So we save one function layer (trigger_thermal_pressure_average()), thermal becomes
more aligned with the other PELT users when it comes to call-sites and we have less
code for this feature.

Something like this (only for 'u64 now' and only compile tested on arm64:

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index be3e802a2dc5..ac3ec3a04469 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -7576,7 +7576,7 @@ static void update_blocked_averages(int cpu)

update_blocked_load_status(rq, !done);

- trigger_thermal_pressure_average(rq);
+ update_thermal_load_avg(rq, per_cpu(delta_capacity, cpu_of(rq)));
rq_unlock_irqrestore(rq, &rf);
}

@@ -9938,7 +9938,7 @@ static void task_tick_fair(struct rq *rq, struct task_struct *curr, int queued)
update_misfit_status(curr, rq);
update_overutilized_status(task_rq(curr));

- trigger_thermal_pressure_average(rq);
+ update_thermal_load_avg(rq, per_cpu(delta_capacity, cpu_of(rq)));
}

/*
diff --git a/kernel/sched/pelt.c b/kernel/sched/pelt.c
index 38210691c615..7dd0d7e43854 100644
--- a/kernel/sched/pelt.c
+++ b/kernel/sched/pelt.c
@@ -353,8 +353,12 @@ int update_dl_rq_load_avg(u64 now, struct rq *rq, int running)
return 0;
}

-int update_thermal_load_avg(u64 now, struct rq *rq, u64 capacity)
+extern int sched_thermal_decay_coeff;
+
+int update_thermal_load_avg(struct rq *rq, u64 capacity)
{
+ u64 now = rq_clock_task(rq) >> sched_thermal_decay_coeff;
+
if (___update_load_sum(now, &rq->avg_thermal,
capacity,
capacity,
diff --git a/kernel/sched/pelt.h b/kernel/sched/pelt.h
index c74226de716e..91483c957b6c 100644
--- a/kernel/sched/pelt.h
+++ b/kernel/sched/pelt.h
@@ -6,7 +6,7 @@ int __update_load_avg_se(u64 now, struct cfs_rq *cfs_rq, struct sched_entity *se
int __update_load_avg_cfs_rq(u64 now, struct cfs_rq *cfs_rq);
int update_rt_rq_load_avg(u64 now, struct rq *rq, int running);
int update_dl_rq_load_avg(u64 now, struct rq *rq, int running);
-int update_thermal_load_avg(u64 now, struct rq *rq, u64 capacity);
+int update_thermal_load_avg(struct rq *rq, u64 capacity);

#ifdef CONFIG_HAVE_SCHED_AVG_IRQ
int update_irq_load_avg(struct rq *rq, u64 running);
diff --git a/kernel/sched/thermal.c b/kernel/sched/thermal.c
index 0da31e12a5ff..7b8c4e35c28d 100644
--- a/kernel/sched/thermal.c
+++ b/kernel/sched/thermal.c
@@ -21,7 +21,7 @@
* 3 256
* 4 512
*/
-static int sched_thermal_decay_coeff;
+int sched_thermal_decay_coeff;

static int __init setup_sched_thermal_decay_coeff(char *str)
{
@@ -32,7 +32,7 @@ static int __init setup_sched_thermal_decay_coeff(char *str)
}
__setup("sched_thermal_decay_coeff=", setup_sched_thermal_decay_coeff);

-static DEFINE_PER_CPU(unsigned long, delta_capacity);
+DEFINE_PER_CPU(unsigned long, delta_capacity);

/**
* update_thermal_pressure: Update thermal pressure
@@ -55,14 +55,3 @@ void update_thermal_pressure(int cpu, u64 capped_freq_ratio)

per_cpu(delta_capacity, cpu) = delta;
}
-
-/**
- * trigger_thermal_pressure_average: Trigger the thermal pressure accumulate
- * and average algorithm
- */
-void trigger_thermal_pressure_average(struct rq *rq)
-{
- update_thermal_load_avg(rq_clock_task(rq) >>
- sched_thermal_decay_coeff, rq,
- per_cpu(delta_capacity, cpu_of(rq)));
-}
diff --git a/kernel/sched/thermal.h b/kernel/sched/thermal.h
index 26e5b07e9c29..a6ee973db41b 100644
--- a/kernel/sched/thermal.h
+++ b/kernel/sched/thermal.h
@@ -2,12 +2,4 @@
/*
* Scheduler thermal interaction internal methods.
*/
-
-#ifdef CONFIG_SMP
-void trigger_thermal_pressure_average(struct rq *rq);
-
-#else
-static inline void trigger_thermal_pressure_average(struct rq *rq)
-{
-}
-#endif
+DECLARE_PER_CPU(unsigned long , delta_capacity);