linux-kernel - Re: [PATCH v3 2/3] sched/fair: use util

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Date:   Wed, 24 Jan 2018 17:03:42 +0530
From:   Pavan Kondeti <pkondeti@...eaurora.org>
To:     Patrick Bellasi <patrick.bellasi@....com>
Cc:     linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Paul Turner <pjt@...gle.com>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Morten Rasmussen <morten.rasmussen@....com>,
        Juri Lelli <juri.lelli@...hat.com>,
        Todd Kjos <tkjos@...roid.com>,
        Joel Fernandes <joelaf@...gle.com>,
        Steve Muckle <smuckle@...gle.com>, pkondeti@...eaurora.org
Subject: Re: [PATCH v3 2/3] sched/fair: use util_est in LB and WU paths

Hi Patrick,

On Tue, Jan 23, 2018 at 06:08:46PM +0000, Patrick Bellasi wrote:
>  static unsigned long cpu_util_wake(int cpu, struct task_struct *p)
>  {
> -	unsigned long util, capacity;
> +	long util, util_est;
>  
>  	/* Task has no contribution or is new */
>  	if (cpu != task_cpu(p) || !p->se.avg.last_update_time)
> -		return cpu_util(cpu);
> +		return cpu_util_est(cpu);
>  
> -	capacity = capacity_orig_of(cpu);
> -	util = max_t(long, cpu_rq(cpu)->cfs.avg.util_avg - task_util(p), 0);
> +	/* Discount task's blocked util from CPU's util */
> +	util = cpu_util(cpu) - task_util(p);
> +	util = max(util, 0L);
>  
> -	return (util >= capacity) ? capacity : util;
> +	if (!sched_feat(UTIL_EST))
> +		return util;

At first, It is not clear to me why you are not clamping the capacity to
CPU original capacity. It looks like it is not needed any more with
commit f453ae2200b0 ("sched/fair: Consider RT/IRQ pressure in
capacity_spare_wake()") inclusion. May be a separate patch to remove
the clamping part?

Thanks,
Pavan
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