Messages in this thread | | | From | Amit Kucheria <> | Date | Thu, 13 Feb 2020 17:33:16 +0530 | Subject | Re: [Patch v8 1/7] sched/pelt: Add support to track thermal pressure |
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On Wed, Jan 15, 2020 at 1:27 AM Thara Gopinath <thara.gopinath@linaro.org> wrote: > > 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> > --- > > 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) > > include/trace/events/sched.h | 4 ++++ > init/Kconfig | 4 ++++ > kernel/sched/pelt.c | 31 +++++++++++++++++++++++++++++++ > kernel/sched/pelt.h | 16 ++++++++++++++++ > kernel/sched/sched.h | 1 + > 5 files changed, 56 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 f6a4a91..c16ea88 100644 > --- a/init/Kconfig > +++ b/init/Kconfig > @@ -450,6 +450,10 @@ 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
May I suggest a slight rewording here and in the commit description,
This is because the thermal pressure signal is weighted "delta" capacity unlike util_avg which is binary.
It would also help, if you expanded on what you mean by binary in the commit description and how the delta capacity is weighted.
> + * capacity" here means delta between the actual capacity of a cpu and the > + * decreased capacity a cpu due to a thermal event.
This could be shortened to:
Delta capacity of cpu = Actual capacity - Decreased capacity due to 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..bf1e17b 100644 > --- a/kernel/sched/pelt.h > +++ b/kernel/sched/pelt.h > @@ -7,6 +7,16 @@ 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); > +#else > +static inline int > +update_thermal_load_avg(u64 now, struct rq *rq, u64 capacity) > +{ > + return 0; > +} > +#endif > + > #ifdef CONFIG_HAVE_SCHED_AVG_IRQ > int update_irq_load_avg(struct rq *rq, u64 running); > #else > @@ -159,6 +169,12 @@ 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; > > -- > 2.1.4 >
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