linux-kernel - Re: [RFC PATCH 2/5] sched: Add NOHZ_STATS

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Message-ID: <CAKfTPtC-kbAU8FsacrbJ5Qrs8qK4LXS5tC5Y4Sky=9vri8VmJg@mail.gmail.com>
Date:   Thu, 1 Feb 2018 18:26:30 +0100
From:   Vincent Guittot <vincent.guittot@...aro.org>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Morten Rasmussen <morten.rasmussen@...s.arm.com>,
        Ingo Molnar <mingo@...nel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Brendan Jackman <brendan.jackman@....com>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Morten Rasmussen <morten.rasmussen@....com>
Subject: Re: [RFC PATCH 2/5] sched: Add NOHZ_STATS_KICK

On 1 February 2018 at 17:57, Peter Zijlstra <peterz@...radead.org> wrote:
> On Wed, Jan 24, 2018 at 09:25:36AM +0100, Vincent Guittot wrote:
>> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
>> index 898785d..ed90303 100644
>> --- a/kernel/sched/fair.c
>> +++ b/kernel/sched/fair.c
>> @@ -7356,6 +7356,17 @@ static inline bool cfs_rq_is_decayed(struct cfs_rq *cfs_rq)
>>       return true;
>>  }
>>
>> +static inline bool cfs_rq_has_blocked(struct cfs_rq *cfs_rq)
>> +{
>> +     if (cfs_rq->avg.load_avg)
>> +             return true;
>> +
>> +     if (cfs_rq->avg.util_avg)
>> +             return true;
>> +
>> +     return false;
>> +}
>> +
>>  #ifdef CONFIG_FAIR_GROUP_SCHED
>>
>>  static void update_blocked_averages(int cpu)
>> @@ -7393,7 +7404,9 @@ static void update_blocked_averages(int cpu)
>>                */
>>               if (cfs_rq_is_decayed(cfs_rq))
>>                       list_del_leaf_cfs_rq(cfs_rq);
>> -             else
>> +
>> +             /* Don't need periodic decay once load/util_avg are null */
>> +             if (cfs_rq_has_blocked(cfs_rq))
>>                       done = false;
>>       }
>>
>> @@ -7463,7 +7476,7 @@ static inline void update_blocked_averages(int cpu)
>>       update_cfs_rq_load_avg(cfs_rq_clock_task(cfs_rq), cfs_rq);
>>  #ifdef CONFIG_NO_HZ_COMMON
>>       rq->last_blocked_load_update_tick = jiffies;
>> -     if (cfs_rq_is_decayed(cfs_rq))
>> +     if (cfs_rq_has_blocked(cfs_rq))
>>               rq->has_blocked_load = 0;
>>  #endif
>>       rq_unlock_irqrestore(rq, &rf);
>
> OK makes sense; would've been even better as a separate patch :-)

Yes  i will make a separate patch for that