linux-kernel - Re: [RFCv5 PATCH 01/46] arm: Frequency invariant scheduler load-tracking support

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Message-ID: <CAKfTPtBsx++wuWjT8XwpUS68ip=_d9BzqXb3SB7Un92WzJo-Gg@mail.gmail.com>
Date:	Mon, 3 Aug 2015 11:22:50 +0200
From:	Vincent Guittot <vincent.guittot@...aro.org>
To:	Morten Rasmussen <morten.rasmussen@....com>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	"mingo@...hat.com" <mingo@...hat.com>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Dietmar Eggemann <Dietmar.Eggemann@....com>,
	Yuyang Du <yuyang.du@...el.com>,
	Michael Turquette <mturquette@...libre.com>,
	"rjw@...ysocki.net" <rjw@...ysocki.net>,
	Juri Lelli <Juri.Lelli@....com>, sgurrappadi@...dia.com,
	pang.xunlei@....com.cn,
	linux-kernel <linux-kernel@...r.kernel.org>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	Russell King <linux@....linux.org.uk>
Subject: Re: [RFCv5 PATCH 01/46] arm: Frequency invariant scheduler
 load-tracking support

Hi Morten,


On 7 July 2015 at 20:23, Morten Rasmussen <morten.rasmussen@....com> wrote:
> From: Morten Rasmussen <Morten.Rasmussen@....com>
>

[snip]

> -
>  #endif
> diff --git a/arch/arm/kernel/topology.c b/arch/arm/kernel/topology.c
> index 08b7847..9c09e6e 100644
> --- a/arch/arm/kernel/topology.c
> +++ b/arch/arm/kernel/topology.c
> @@ -169,6 +169,23 @@ static void update_cpu_capacity(unsigned int cpu)
>                 cpu, arch_scale_cpu_capacity(NULL, cpu));
>  }
>
> +/*
> + * Scheduler load-tracking scale-invariance
> + *
> + * Provides the scheduler with a scale-invariance correction factor that
> + * compensates for frequency scaling (arch_scale_freq_capacity()). The scaling
> + * factor is updated in smp.c
> + */
> +unsigned long arm_arch_scale_freq_capacity(struct sched_domain *sd, int cpu)
> +{
> +       unsigned long curr = atomic_long_read(&per_cpu(cpu_freq_capacity, cpu));

access to cpu_freq_capacity to should be put under #ifdef CONFIG_CPU_FREQ.

Why haven't you moved arm_arch_scale_freq_capacity in smp.c as
everything else for frequency in-variance is already in this file ?
This should also enable you to remove
DECLARE_PER_CPU(atomic_long_t, cpu_freq_capacity); from topology.h

Vincent

> +
> +       if (!curr)
> +               return SCHED_CAPACITY_SCALE;
> +
> +       return curr;
> +}
> +
>  #else
>  static inline void parse_dt_topology(void) {}
>  static inline void update_cpu_capacity(unsigned int cpuid) {}
> --
> 1.9.1
>
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