linux-kernel - Re: [PATCH v4 05/10] sched/topology: Define and assign sched

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Message-ID: <20200806140750.GC2077896@gmail.com>
Date:   Thu, 6 Aug 2020 16:07:50 +0200
From:   Ingo Molnar <mingo@...nel.org>
To:     Valentin Schneider <valentin.schneider@....com>
Cc:     linux-kernel@...r.kernel.org, peterz@...radead.org,
        vincent.guittot@...aro.org, dietmar.eggemann@....com,
        morten.rasmussen@....com, Quentin Perret <qperret@...gle.com>
Subject: Re: [PATCH v4 05/10] sched/topology: Define and assign sched_domain
 flag metadata


* Valentin Schneider <valentin.schneider@....com> wrote:

> +#ifndef SD_FLAG
> +#define SD_FLAG(x, y, z)
> +#endif

AFAICS there's not a single use of sd_flags.h that doesn't come with 
its own SD_FLAG definition, so I suppose this should be:

#ifndef SD_FLAG
# error "Should not happen."
#endif

?

Also, some nits:

> +/*
> + * Expected flag uses
> + *
> + * SHARED_CHILD: These flags are meant to be set from the base domain upwards.
> + * If a domain has this flag set, all of its children should have it set. This
> + * is usually because the flag describes some shared resource (all CPUs in that
> + * domain share the same foobar), or because they are tied to a scheduling
> + * behaviour that we want to disable at some point in the hierarchy for
> + * scalability reasons.

s/foobar/resource

?

> +/*
> + * cross-node balancing
> + *
> + * SHARED_PARENT: Set for all NUMA levels above NODE.
> + */
> +SD_FLAG(SD_NUMA,                12, SDF_SHARED_PARENT)

s/cross-node/Cross-node

BTW., is there any particular reason why these need to be defines with 
a manual enumeration of flag values - couldn't we generate 
auto-enumerated C enums instead or so?

> +#ifdef CONFIG_SCHED_DEBUG
> +#define SD_FLAG(_name, idx, mflags) [idx] = {.meta_flags = mflags, .name = #_name},

s/{./{ .
s/e}/e }

Thanks,

	Ingo