linux-kernel - Re: [Patch v3 1/7] sched/pelt.c: Add support to track thermal pressure

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Message-ID: <5DA7888C.3050406@linaro.org>
Date:   Wed, 16 Oct 2019 17:15:56 -0400
From:   Thara Gopinath <thara.gopinath@...aro.org>
To:     Vincent Guittot <vincent.guittot@...aro.org>
Cc:     Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ionela Voinescu <ionela.voinescu@....com>,
        Zhang Rui <rui.zhang@...el.com>,
        Eduardo Valentin <edubezval@...il.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Amit Kachhap <amit.kachhap@...il.com>,
        Javi Merino <javi.merino@...nel.org>,
        Daniel Lezcano <daniel.lezcano@...aro.org>
Subject: Re: [Patch v3 1/7] sched/pelt.c: Add support to track thermal
 pressure

Hi Vincent,

Thanks for the review.
On 10/14/2019 09:55 AM, Vincent Guittot wrote:
> Hi Thara,
> 
> On Mon, 14 Oct 2019 at 02:58, Thara Gopinath <thara.gopinath@...aro.org> wrote:
>>
>> Extrapolating on the exisitng framework to track rt/dl utilization using
> 
> s/exisitng/existing/
> 
>> pelt signals, add a similar mechanism to track thermal pressue. The
> 
> s/pessure/pressure/
Will fix all the typo.
> 
>> 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.
> 
> It would be good to mention why you use load_avg field instead of
> util_avg field: because the signal is weighted with the capped
> capacity and is not binary
> And also explained a bit what capacity refer to
> 
>> In order to track average thermal pressure, a new sched_avg variable
>> avg_thermal is introduced. Function update_thermal_avg can be called
>> to do the periodic bookeeping (accumulate, decay and average)
>> of the thermal pressure.
>>
>> Signed-off-by: Thara Gopinath <thara.gopinath@...aro.org>
>> ---
>>  kernel/sched/pelt.c  | 13 +++++++++++++
>>  kernel/sched/pelt.h  |  7 +++++++
>>  kernel/sched/sched.h |  1 +
>>  3 files changed, 21 insertions(+)
>>
>> diff --git a/kernel/sched/pelt.c b/kernel/sched/pelt.c
>> index a96db50..f06aae3 100644
>> --- a/kernel/sched/pelt.c
>> +++ b/kernel/sched/pelt.c
>> @@ -353,6 +353,19 @@ int update_dl_rq_load_avg(u64 now, struct rq *rq, int running)
>>         return 0;
>>  }
>>
>> +int update_thermal_avg(u64 now, struct rq *rq, u64 capacity)
> 
> All the other functions are named :
> update_cfs_rq/rt_rq/dl_rq/irq_load_avg
> 
> might be good to keep similar name with update_thermal_load_avg

Sure. Will rename the function.
> 
>> +{
>> +       if (___update_load_sum(now, &rq->avg_thermal,
>> +                              capacity,
>> +                              capacity,
>> +                              capacity)) {
>> +               ___update_load_avg(&rq->avg_thermal, 1, 1);
>> +               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..01c5436 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_avg(u64 now, struct rq *rq, u64 capacity);
>>
>>  #ifdef CONFIG_HAVE_SCHED_AVG_IRQ
>>  int update_irq_load_avg(struct rq *rq, u64 running);
>> @@ -175,6 +176,12 @@ update_rq_clock_pelt(struct rq *rq, s64 delta) { }
>>  static inline void
>>  update_idle_rq_clock_pelt(struct rq *rq) { }
>>
>> +static inline int
> 
> can you keep some function ordering as above and move
> update_thermal_avg() just after update_dl_rq_load_avg

will do.

Warm Regards
Thara