linux-kernel - Re: [RFC PATCH 4/5] sched/events: Introduce sched

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Message-ID: <4b0fb4a2-90e0-38cb-aea5-bbfe8efaf65c@arm.com>
Date:   Tue, 28 Mar 2017 16:03:25 +0200
From:   Dietmar Eggemann <dietmar.eggemann@....com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Ingo Molnar <mingo@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Matt Fleming <matt@...eblueprint.co.uk>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Morten Rasmussen <morten.rasmussen@....com>,
        Juri Lelli <juri.lelli@....com>,
        Patrick Bellasi <patrick.bellasi@....com>
Subject: Re: [RFC PATCH 4/5] sched/events: Introduce sched_entity load
 tracking trace event

On 03/28/2017 10:05 AM, Peter Zijlstra wrote:
> On Tue, Mar 28, 2017 at 07:35:40AM +0100, Dietmar Eggemann wrote:
>> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
>> index 04d4f81b96ae..d1dcb19f5b55 100644
>> --- a/kernel/sched/fair.c
>> +++ b/kernel/sched/fair.c
>> @@ -2940,6 +2940,8 @@ __update_load_avg(u64 now, int cpu, struct sched_avg *sa,
>>
>>  	if (cfs_rq)
>>  		trace_sched_load_cfs_rq(cfs_rq);
>> +	else
>> +		trace_sched_load_se(container_of(sa, struct sched_entity, avg));
>>
>>  	return decayed;
>>  }
>> @@ -3162,6 +3164,7 @@ static inline int propagate_entity_load_avg(struct sched_entity *se)
>>  	update_tg_cfs_load(cfs_rq, se);
>>
>>  	trace_sched_load_cfs_rq(cfs_rq);
>> +	trace_sched_load_se(se);
>>
>>  	return 1;
>>  }
>
> Having back-to-back tracepoints is disgusting.

Yeah, but avoiding putting them like this is hard since the calls to 
update_tg_cfs_util() and update_tg_cfs_load() inside 
propagate_entity_load_avg() refresh util for the cfs_rq and the se 
respectively load (and runnable_load).