Commit 76504793 authored by Thara Gopinath's avatar Thara Gopinath Committed by Ingo Molnar

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 time "delta" capacity unlike util_avg
which 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.
Reviewed-by: default avatarVincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: default avatarThara Gopinath <thara.gopinath@linaro.org>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20200222005213.3873-2-thara.gopinath@linaro.org
parent f1dfdab6
......@@ -618,6 +618,10 @@ 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));
......
......@@ -451,6 +451,10 @@ config HAVE_SCHED_AVG_IRQ
depends on IRQ_TIME_ACCOUNTING || PARAVIRT_TIME_ACCOUNTING
depends on SMP
config SCHED_THERMAL_PRESSURE
bool "Enable periodic averaging of thermal pressure"
depends on SMP
config BSD_PROCESS_ACCT
bool "BSD Process Accounting"
depends on MULTIUSER
......
......@@ -368,6 +368,37 @@ int update_dl_rq_load_avg(u64 now, struct rq *rq, int running)
return 0;
}
#ifdef CONFIG_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
* time weighted "delta" capacity unlike util_avg which is binary.
* "delta capacity" = actual capacity -
* capped 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);
trace_pelt_thermal_tp(rq);
return 1;
}
return 0;
}
#endif
#ifdef CONFIG_HAVE_SCHED_AVG_IRQ
/*
* irq:
......
......@@ -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_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
......@@ -158,6 +178,17 @@ update_dl_rq_load_avg(u64 now, struct rq *rq, int running)
return 0;
}
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)
{
......
......@@ -960,6 +960,9 @@ struct rq {
struct sched_avg avg_dl;
#ifdef CONFIG_HAVE_SCHED_AVG_IRQ
struct sched_avg avg_irq;
#endif
#ifdef CONFIG_SCHED_THERMAL_PRESSURE
struct sched_avg avg_thermal;
#endif
u64 idle_stamp;
u64 avg_idle;
......
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