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Date: Tue, 28 Jan 2020 17:36:00 -0500
From: Thara Gopinath <thara.gopinath@...aro.org>
To: mingo@...hat.com, peterz@...radead.org, ionela.voinescu@....com,
vincent.guittot@...aro.org, dietmar.eggemann@....com,
rui.zhang@...el.com, qperret@...gle.com, daniel.lezcano@...aro.org,
viresh.kumar@...aro.org, rostedt@...dmis.org, will@...nel.org,
catalin.marinas@....com, sudeep.holla@....com,
juri.lelli@...hat.com, corbet@....net
Cc: linux-kernel@...r.kernel.org, amit.kachhap@...il.com,
javi.merino@...nel.org, amit.kucheria@...durent.com
Subject: [Patch v9 1/8] sched/pelt: Add support to track thermal pressure
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@...aro.org>
Reviewed-by: Vincent Guittot <vincent.guittot@...aro.org>
---
v6->v7:
- Added CONFIG_HAVE_SCHED_THERMAL_PRESSURE to stub out
update_thermal_load_avg in unsupported architectures as per
review comments from Peter, Dietmar and Quentin.
- Updated comment for update_thermal_load_avg as per review
comments from Peter and Dietmar.
v7->v8:
- Fixed typo in defining update_thermal_load_avg which was
causing build errors (reported by kbuild test report)
v8->v9:
- Defined thermal_load_avg to read rq->avg_thermal.load_avg and
avoid cacheline miss in unsupported cases as per Peter's
suggestion.
include/trace/events/sched.h | 4 ++++
init/Kconfig | 4 ++++
kernel/sched/pelt.c | 31 +++++++++++++++++++++++++++++++
kernel/sched/pelt.h | 31 +++++++++++++++++++++++++++++++
kernel/sched/sched.h | 3 +++
5 files changed, 73 insertions(+)
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/init/Kconfig b/init/Kconfig
index bd9f1fd..055c3bf 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -463,6 +463,10 @@ config HAVE_SCHED_AVG_IRQ
depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING
depends on SMP
+config HAVE_SCHED_THERMAL_PRESSURE
+ bool "Enable periodic averaging of thermal pressure"
+ depends on SMP
+
config BSD_PROCESS_ACCT
bool "BSD Process Accounting"
depends on MULTIUSER
diff --git a/kernel/sched/pelt.c b/kernel/sched/pelt.c
index bd006b7..5d1fbf0 100644
--- a/kernel/sched/pelt.c
+++ b/kernel/sched/pelt.c
@@ -367,6 +367,37 @@ int update_dl_rq_load_avg(u64 now, struct rq *rq, int running)
return 0;
}
+#ifdef CONFIG_HAVE_SCHED_THERMAL_PRESSURE
+/*
+ * thermal:
+ *
+ * load_sum = \Sum se->avg.load_sum but se->avg.load_sum is not tracked
+ *
+ * util_avg and runnable_load_avg are not supported and meaningless.
+ *
+ * Unlike rt/dl utilization tracking that track 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.
+ */
+
+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;
+}
+#endif
+
#ifdef CONFIG_HAVE_SCHED_AVG_IRQ
/*
* irq:
diff --git a/kernel/sched/pelt.h b/kernel/sched/pelt.h
index afff644..916979a 100644
--- a/kernel/sched/pelt.h
+++ b/kernel/sched/pelt.h
@@ -7,6 +7,26 @@ 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);
+#ifdef CONFIG_HAVE_SCHED_THERMAL_PRESSURE
+int update_thermal_load_avg(u64 now, struct rq *rq, u64 capacity);
+
+static inline u64 thermal_load_avg(struct rq *rq)
+{
+ return READ_ONCE(rq->avg_thermal.load_avg);
+}
+#else
+static inline int
+update_thermal_load_avg(u64 now, struct rq *rq, u64 capacity)
+{
+ return 0;
+}
+
+static inline u64 thermal_load_avg(struct rq *rq)
+{
+ return 0;
+}
+#endif
+
#ifdef CONFIG_HAVE_SCHED_AVG_IRQ
int update_irq_load_avg(struct rq *rq, u64 running);
#else
@@ -159,6 +179,17 @@ 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 u64 thermal_load_avg(struct rq *rq)
+{
+ 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 1a88dc8..1f256cb 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -944,6 +944,9 @@ struct rq {
#ifdef CONFIG_HAVE_SCHED_AVG_IRQ
struct sched_avg avg_irq;
#endif
+#ifdef CONFIG_HAVE_SCHED_THERMAL_PRESSURE
+ struct sched_avg avg_thermal;
+#endif
u64 idle_stamp;
u64 avg_idle;
--
2.1.4
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