linux-kernel - Re: [PATCH v5 03/10] cpufreq/schedutil: add rt utilization tracking

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Date:   Wed, 30 May 2018 11:53:46 +0200
From:   Vincent Guittot <vincent.guittot@...aro.org>
To:     Patrick Bellasi <patrick.bellasi@....com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Juri Lelli <juri.lelli@...hat.com>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Morten Rasmussen <Morten.Rasmussen@....com>,
        viresh kumar <viresh.kumar@...aro.org>,
        Valentin Schneider <valentin.schneider@....com>,
        Quentin Perret <quentin.perret@....com>
Subject: Re: [PATCH v5 03/10] cpufreq/schedutil: add rt utilization tracking

On 30 May 2018 at 11:40, Patrick Bellasi <patrick.bellasi@....com> wrote:
> On 25-May 15:12, Vincent Guittot wrote:
>> Add both cfs and rt utilization when selecting an OPP for cfs tasks as rt
>> can preempt and steal cfs's running time.
>>
>> Signed-off-by: Vincent Guittot <vincent.guittot@...aro.org>
>> ---
>>  kernel/sched/cpufreq_schedutil.c | 14 +++++++++++---
>>  1 file changed, 11 insertions(+), 3 deletions(-)
>>
>> diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c
>> index 28592b6..a84b5a5 100644
>> --- a/kernel/sched/cpufreq_schedutil.c
>> +++ b/kernel/sched/cpufreq_schedutil.c
>> @@ -56,6 +56,7 @@ struct sugov_cpu {
>>       /* The fields below are only needed when sharing a policy: */
>>       unsigned long           util_cfs;
>>       unsigned long           util_dl;
>> +     unsigned long           util_rt;
>>       unsigned long           max;
>>
>>       /* The field below is for single-CPU policies only: */
>> @@ -178,14 +179,21 @@ static void sugov_get_util(struct sugov_cpu *sg_cpu)
>>       sg_cpu->max = arch_scale_cpu_capacity(NULL, sg_cpu->cpu);
>>       sg_cpu->util_cfs = cpu_util_cfs(rq);
>>       sg_cpu->util_dl  = cpu_util_dl(rq);
>> +     sg_cpu->util_rt  = cpu_util_rt(rq);
>>  }
>>
>>  static unsigned long sugov_aggregate_util(struct sugov_cpu *sg_cpu)
>>  {
>>       struct rq *rq = cpu_rq(sg_cpu->cpu);
>> +     unsigned long util;
>>
>> -     if (rq->rt.rt_nr_running)
>> -             return sg_cpu->max;
>> +     if (rq->rt.rt_nr_running) {
>> +             util = sg_cpu->max;
>
> Why not just adding the following lines while keeping the return in
> for the rq->rt.rt_nr_running case?
>
>> +     } else {
>> +             util = sg_cpu->util_dl;
>> +             util += sg_cpu->util_cfs;
>> +             util += sg_cpu->util_rt;
>> +     }
>>
>>       /*
>>        * Utilization required by DEADLINE must always be granted while, for
>> @@ -197,7 +205,7 @@ static unsigned long sugov_aggregate_util(struct sugov_cpu *sg_cpu)
>>        * util_cfs + util_dl as requested freq. However, cpufreq is not yet
>>        * ready for such an interface. So, we only do the latter for now.
>>        */
>> -     return min(sg_cpu->max, (sg_cpu->util_dl + sg_cpu->util_cfs));
>> +     return min(sg_cpu->max, util);
>
> ... for the rq->rt.rt_nr_running case we don't really need to min
> clamp util = sg_cpu->max with itself...

yes good point

>
>>  }
>>
>>  static void sugov_set_iowait_boost(struct sugov_cpu *sg_cpu, u64 time, unsigned int flags)
>> --
>> 2.7.4
>>
>
> --
> #include <best/regards.h>
>
> Patrick Bellasi