linux-kernel - Re: [PATCH -tip 31/32] sched: Add a coresched command line option

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Message-ID: <2080fa5d-0a64-b006-d746-eb6de42aed8f@infradead.org>
Date:   Thu, 19 Nov 2020 15:39:15 -0800
From:   Randy Dunlap <rdunlap@...radead.org>
To:     "Joel Fernandes (Google)" <joel@...lfernandes.org>,
        Nishanth Aravamudan <naravamudan@...italocean.com>,
        Julien Desfossez <jdesfossez@...italocean.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Tim Chen <tim.c.chen@...ux.intel.com>,
        Vineeth Pillai <viremana@...ux.microsoft.com>,
        Aaron Lu <aaron.lwe@...il.com>,
        Aubrey Li <aubrey.intel@...il.com>, tglx@...utronix.de,
        linux-kernel@...r.kernel.org
Cc:     mingo@...nel.org, torvalds@...ux-foundation.org,
        fweisbec@...il.com, keescook@...omium.org, kerrnel@...gle.com,
        Phil Auld <pauld@...hat.com>,
        Valentin Schneider <valentin.schneider@....com>,
        Mel Gorman <mgorman@...hsingularity.net>,
        Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>,
        Paolo Bonzini <pbonzini@...hat.com>, vineeth@...byteword.org,
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        Tim Chen <tim.c.chen@...el.com>
Subject: Re: [PATCH -tip 31/32] sched: Add a coresched command line option

Hi Joel,

On 11/17/20 3:20 PM, Joel Fernandes (Google) wrote:
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index b185c6ed4aba..9cd2cf7c18d4 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -698,6 +698,20 @@
>  			/proc/<pid>/coredump_filter.
>  			See also Documentation/filesystems/proc.rst.
>  
> +	coresched=	[SCHED_CORE] This feature allows the Linux scheduler

Unless I missed it somewhere else, this "SCHED_CORE" string should be
added to Documentation/admin-guide/kernel-parameters.rst, where there is
a list of "qualifiers" for kernel parameters.

(It looks like you are using it as the name of a Kconfig option, which
makes some sense, but that's not how it's [currently] done. :)


> +			to force hyperthread siblings of a CPU to only execute tasks
> +			concurrently on all hyperthreads that are running within the
> +			same core scheduling group.
> +			Possible values are:
> +			'on' - Enable scheduler capability to core schedule.
> +			By default, no tasks will be core scheduled, but the coresched
> +			interface can be used to form groups of tasks that are forced
> +			to share a core.
> +			'off' - Disable scheduler capability to core schedule.
> +			'secure' - Like 'on' but only enable on systems affected by
> +			MDS or L1TF vulnerabilities. 'off' otherwise.
> +			Default: 'secure'.
> +
>  	coresight_cpu_debug.enable
>  			[ARM,ARM64]
>  			Format: <bool>

thanks.
-- 
~Randy