linux-kernel - Re: [RFC PATCH 1/6] sched/dl: Improve deadline admission control for asymmetric CPU capacities

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Message-ID: <20190507134850.yreebscc3zigfmtd@queper01-lin>
Date:   Tue, 7 May 2019 14:48:52 +0100
From:   Quentin Perret <quentin.perret@....com>
To:     Luca Abeni <luca.abeni@...tannapisa.it>
Cc:     linux-kernel@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        "Paul E . McKenney" <paulmck@...ux.ibm.com>,
        Joel Fernandes <joel@...lfernandes.org>,
        Luc Van Oostenryck <luc.vanoostenryck@...il.com>,
        Morten Rasmussen <morten.rasmussen@....com>,
        Juri Lelli <juri.lelli@...hat.com>,
        Daniel Bristot de Oliveira <bristot@...hat.com>,
        Patrick Bellasi <patrick.bellasi@....com>,
        Tommaso Cucinotta <tommaso.cucinotta@...tannapisa.it>
Subject: Re: [RFC PATCH 1/6] sched/dl: Improve deadline admission control for
 asymmetric CPU capacities

Hi Luca,

On Monday 06 May 2019 at 06:48:31 (+0200), Luca Abeni wrote:
> diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c
> index edfcf8d982e4..646d6d349d53 100644
> --- a/drivers/base/arch_topology.c
> +++ b/drivers/base/arch_topology.c
> @@ -36,6 +36,7 @@ DEFINE_PER_CPU(unsigned long, cpu_scale) = SCHED_CAPACITY_SCALE;
>  
>  void topology_set_cpu_scale(unsigned int cpu, unsigned long capacity)
>  {
> +	topology_update_cpu_capacity(cpu, per_cpu(cpu_scale, cpu), capacity);

Why is that one needed ? Don't you end up re-building the sched domains
after this anyways ?

>  	per_cpu(cpu_scale, cpu) = capacity;
>  }

Thanks,
Quentin