linux-kernel - Re: [PATCH 1/3] ARM: exynos_defconfig: Enable SCHED

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Message-ID: <CAJKOXPedRc3ag6DDUAXSbHk8JcAZbug5HSss9wb8YyLkP7MLaw@mail.gmail.com>
Date:   Fri, 31 Jan 2020 13:47:39 +0100
From:   Krzysztof Kozlowski <krzk@...nel.org>
To:     lukasz.luba@....com
Cc:     kgene@...nel.org, linux-arm-kernel@...ts.infradead.org,
        "linux-samsung-soc@...r.kernel.org" 
        <linux-samsung-soc@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        devicetree@...r.kernel.org, linux-pm@...r.kernel.org,
        myungjoo.ham@...sung.com, kyungmin.park@...sung.com,
        Chanwoo Choi <cw00.choi@...sung.com>, robh+dt@...nel.org,
        mark.rutland@....com,
        Bartłomiej Żołnierkiewicz 
        <b.zolnierkie@...sung.com>, dietmar.eggemann@....com
Subject: Re: [PATCH 1/3] ARM: exynos_defconfig: Enable SCHED_MC

On Mon, 27 Jan 2020 at 22:55, <lukasz.luba@....com> wrote:
>
> From: Lukasz Luba <lukasz.luba@....com>
>
> Since the 'capacities-dmips-mhz' are present in the CPU nodes, make use of
> this knowledge in smarter decisions during scheduling.
>
> The values in 'capacities-dmips-mhz' are normilized, this means that i.e.
> when CPU0's capacities-dmips-mhz=100 and CPU1's 'capacities-dmips-mhz'=50,
> cpu0 is twice fast as CPU1, at the same frequency. The proper hirarchy
> in sched_domain topology could exploit the SoC architecture advantages
> like big.LITTLE.

I do not quite get how this is related to rationale behind changing defconfig...

> Enabling the SCHED_MC will create two levels in
> sched_domain hierarchy, which might be observed in:

This is looks more convincing... but still what is the need? To work with EAS?

> grep . /proc/sys/kernel/sched_domain/cpu*/domain*/{name,flags}
> /proc/sys/kernel/sched_domain/cpu0/domain0/name:MC
> /proc/sys/kernel/sched_domain/cpu0/domain1/name:DIE
> ...
> /proc/sys/kernel/sched_domain/cpu0/domain0/flags:575
> /proc/sys/kernel/sched_domain/cpu0/domain1/flags:4223

Not related to defconfig change and not visible after this commit.

Best regards,
Krzysztof

>
> Signed-off-by: Lukasz Luba <lukasz.luba@....com>
> ---
>  arch/arm/configs/exynos_defconfig | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/arch/arm/configs/exynos_defconfig b/arch/arm/configs/exynos_defconfig
> index e7e4bb5ad8d5..1db857056992 100644
> --- a/arch/arm/configs/exynos_defconfig
> +++ b/arch/arm/configs/exynos_defconfig
> @@ -8,6 +8,7 @@ CONFIG_PERF_EVENTS=y
>  CONFIG_ARCH_EXYNOS=y
>  CONFIG_CPU_ICACHE_MISMATCH_WORKAROUND=y
>  CONFIG_SMP=y
> +CONFIG_SCHED_MC=y
>  CONFIG_BIG_LITTLE=y
>  CONFIG_NR_CPUS=8
>  CONFIG_HIGHMEM=y
> --
> 2.17.1
>