linux-kernel - Re: [PATCH v8 4/8] x86/sysctl: Add sysctl for ITMT scheduling feature

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Message-ID: <20161128085608.v7ujy5j2iftn6qs5@pd.tnic>
Date:   Mon, 28 Nov 2016 09:56:08 +0100
From:   Borislav Petkov <bp@...e.de>
To:     Tim Chen <tim.c.chen@...ux.intel.com>
Cc:     rjw@...ysocki.net, tglx@...utronix.de, mingo@...hat.com,
        x86@...nel.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
        peterz@...radead.org, jolsa@...hat.com,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
Subject: Re: [PATCH v8 4/8] x86/sysctl: Add sysctl for ITMT scheduling feature

On Tue, Nov 22, 2016 at 12:23:56PM -0800, Tim Chen wrote:
> Intel Turbo Boost Max Technology 3.0 (ITMT) feature
> allows some cores to be boosted to higher turbo
> frequency than others.
> 
> Add /proc/sys/kernel/sched_itmt_enabled so operator
> can enable/disable scheduling of tasks that favor cores
> with higher turbo boost frequency potential.
> 
> By default, system that is ITMT capable and single
> socket has this feature turned on.  It is more likely
> to be lightly loaded and operates in Turbo range.
> 
> When there is a change in the ITMT scheduling operation
> desired, a rebuild of the sched domain is initiated
> so the scheduler can set up sched domains with appropriate
> flag to enable/disable ITMT scheduling operations.
> 
> Co-developed-by: Peter Zijlstra (Intel) <peterz@...radead.org>
> Co-developed-by: Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
> Signed-off-by: Tim Chen <tim.c.chen@...ux.intel.com>
> ---
>  arch/x86/include/asm/topology.h |   7 ++-
>  arch/x86/kernel/itmt.c          | 108 +++++++++++++++++++++++++++++++++++++++-
>  2 files changed, 112 insertions(+), 3 deletions(-)

...

> +/*
> + * Boolean to control whether we want to move processes to cpu capable
> + * of higher turbo frequency for cpus supporting Intel Turbo Boost Max
> + * Technology 3.0.
> + *
> + * It can be set via /proc/sys/kernel/sched_itmt_enabled
> + */
> +unsigned int __read_mostly sysctl_sched_itmt_enabled;

Err, can we not have the boolean in the name itself?

I.e., have it called sysctl_sched_itmt and 1 means enabled and 0
disabled? I.e., the classic thing. :)

Ditto for the sysctl name?

-- 
Regards/Gruss,
    Boris.

SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
--