[v6,1/7] sched/pelt.c: Add support to track thermal pressure

Message ID 1576123908-12105-2-git-send-email-thara.gopinath@linaro.org
State New
Headers show
Series
  • Introduce Thermal Pressure
Related show

Commit Message

Thara Gopinath Dec. 12, 2019, 4:11 a.m.
Extrapolating on the existing framework to track rt/dl utilization using
pelt signals, add a similar mechanism to track thermal pressure. The
difference here from rt/dl utilization tracking is that, instead of
tracking time spent by a cpu running a rt/dl task through util_avg, the
average thermal pressure is tracked through load_avg. This is because
thermal pressure signal is weighted "delta" capacity and is not
binary(util_avg is binary). "delta capacity" here means delta between the
actual capacity of a cpu and the decreased capacity a cpu due to a thermal
event.

In order to track average thermal pressure, a new sched_avg variable
avg_thermal is introduced. Function update_thermal_load_avg can be called
to do the periodic bookkeeping (accumulate, decay and average) of the
thermal pressure.

Signed-off-by: Thara Gopinath <thara.gopinath@linaro.org>

Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>

---

v5->v6:
	- added trace support for thermal pressure pelt signal.

 include/trace/events/sched.h |  4 ++++
 kernel/sched/pelt.c          | 22 ++++++++++++++++++++++
 kernel/sched/pelt.h          |  7 +++++++
 kernel/sched/sched.h         |  1 +
 4 files changed, 34 insertions(+)

-- 
2.1.4

Comments

Peter Zijlstra Dec. 16, 2019, 1:43 p.m. | #1
On Wed, Dec 11, 2019 at 11:11:42PM -0500, Thara Gopinath wrote:
> The

> difference here from rt/dl utilization tracking is that, instead of

> tracking time spent by a cpu running a rt/dl task through util_avg, the

> average thermal pressure is tracked through load_avg. This is because

> thermal pressure signal is weighted "delta" capacity and is not

> binary(util_avg is binary). "delta capacity" here means delta between the

> actual capacity of a cpu and the decreased capacity a cpu due to a thermal

> event.


I'm thinking that ^, would make a nice adding to that v.

> +/*

> + * thermal:

> + *

> + *   load_sum = \Sum se->avg.load_sum

> + *

> + *   util_avg and runnable_load_avg are not supported and meaningless.

> + *

> + */

> +int update_thermal_load_avg(u64 now, struct rq *rq, u64 capacity)

> +{

> +	if (___update_load_sum(now, &rq->avg_thermal,

> +			       capacity,

> +			       capacity,

> +			       capacity)) {

> +		___update_load_avg(&rq->avg_thermal, 1, 1);

> +		trace_pelt_thermal_tp(rq);

> +		return 1;

> +	}

> +

> +	return 0;

> +}
Dietmar Eggemann Dec. 17, 2019, 12:54 p.m. | #2
On 12/12/2019 05:11, Thara Gopinath wrote:

minor: in subject: s/sched/pelt.c/sched/pelt

[...]

> diff --git a/kernel/sched/pelt.c b/kernel/sched/pelt.c

> index a96db50..9aac3b7 100644

> --- a/kernel/sched/pelt.c

> +++ b/kernel/sched/pelt.c

> @@ -353,6 +353,28 @@ int update_dl_rq_load_avg(u64 now, struct rq *rq, int running)

>  	return 0;

>  }

>  

> +/*

> + * thermal:

> + *

> + *   load_sum = \Sum se->avg.load_sum


Why not '\Sum rq->avg.load_sum' ?

> + *

> + *   util_avg and runnable_load_avg are not supported and meaningless.

> + *

> + */

> +int update_thermal_load_avg(u64 now, struct rq *rq, u64 capacity)

> +{

> +	if (___update_load_sum(now, &rq->avg_thermal,

> +			       capacity,

> +			       capacity,

> +			       capacity)) {

> +		___update_load_avg(&rq->avg_thermal, 1, 1);

> +		trace_pelt_thermal_tp(rq);

> +		return 1;

> +	}

> +

> +	return 0;

> +}

> +


[...]
Ionela Voinescu Dec. 23, 2019, 5:56 p.m. | #3
On Wednesday 11 Dec 2019 at 23:11:42 (-0500), Thara Gopinath wrote:
[...]
> diff --git a/kernel/sched/pelt.h b/kernel/sched/pelt.h

> index afff644..c74226d 100644

> --- a/kernel/sched/pelt.h

> +++ b/kernel/sched/pelt.h

> @@ -6,6 +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);

>


I know a lot of people have come with suggestions for this name, but how
about update_th_rq_load_avg :)? Only if you're in the mood to change it
again.

Regards,
Ionela.

Patch

diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h
index 420e80e..a8fb667 100644
--- a/include/trace/events/sched.h
+++ b/include/trace/events/sched.h
@@ -613,6 +613,10 @@  DECLARE_TRACE(pelt_dl_tp,
 	TP_PROTO(struct rq *rq),
 	TP_ARGS(rq));
 
+DECLARE_TRACE(pelt_thermal_tp,
+	TP_PROTO(struct rq *rq),
+	TP_ARGS(rq));
+
 DECLARE_TRACE(pelt_irq_tp,
 	TP_PROTO(struct rq *rq),
 	TP_ARGS(rq));
diff --git a/kernel/sched/pelt.c b/kernel/sched/pelt.c
index a96db50..9aac3b7 100644
--- a/kernel/sched/pelt.c
+++ b/kernel/sched/pelt.c
@@ -353,6 +353,28 @@  int update_dl_rq_load_avg(u64 now, struct rq *rq, int running)
 	return 0;
 }
 
+/*
+ * thermal:
+ *
+ *   load_sum = \Sum se->avg.load_sum
+ *
+ *   util_avg and runnable_load_avg are not supported and meaningless.
+ *
+ */
+int update_thermal_load_avg(u64 now, struct rq *rq, u64 capacity)
+{
+	if (___update_load_sum(now, &rq->avg_thermal,
+			       capacity,
+			       capacity,
+			       capacity)) {
+		___update_load_avg(&rq->avg_thermal, 1, 1);
+		trace_pelt_thermal_tp(rq);
+		return 1;
+	}
+
+	return 0;
+}
+
 #ifdef CONFIG_HAVE_SCHED_AVG_IRQ
 /*
  * irq:
diff --git a/kernel/sched/pelt.h b/kernel/sched/pelt.h
index afff644..c74226d 100644
--- a/kernel/sched/pelt.h
+++ b/kernel/sched/pelt.h
@@ -6,6 +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);
 
 #ifdef CONFIG_HAVE_SCHED_AVG_IRQ
 int update_irq_load_avg(struct rq *rq, u64 running);
@@ -159,6 +160,12 @@  update_dl_rq_load_avg(u64 now, struct rq *rq, int running)
 }
 
 static inline int
+update_thermal_load_avg(u64 now, struct rq *rq, u64 capacity)
+{
+	return 0;
+}
+
+static inline int
 update_irq_load_avg(struct rq *rq, u64 running)
 {
 	return 0;
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 280a3c7..37bd7ef 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -944,6 +944,7 @@  struct rq {
 #ifdef CONFIG_HAVE_SCHED_AVG_IRQ
 	struct sched_avg	avg_irq;
 #endif
+	struct sched_avg	avg_thermal;
 	u64			idle_stamp;
 	u64			avg_idle;