linux-kernel - RE: [PATCH v5 7/8] x86/resctrl: Update documentation with Sub-NUMA cluster changes

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Message-ID: <SJ1PR11MB60831009ACAC814C4F2A6072FCC3A@SJ1PR11MB6083.namprd11.prod.outlook.com>
Date:   Tue, 26 Sep 2023 19:11:27 +0000
From:   "Luck, Tony" <tony.luck@...el.com>
To:     "babu.moger@....com" <babu.moger@....com>,
        "Yu, Fenghua" <fenghua.yu@...el.com>,
        "Chatre, Reinette" <reinette.chatre@...el.com>,
        Peter Newman <peternewman@...gle.com>,
        Jonathan Corbet <corbet@....net>,
        Shuah Khan <skhan@...uxfoundation.org>,
        "x86@...nel.org" <x86@...nel.org>
CC:     Shaopeng Tan <tan.shaopeng@...itsu.com>,
        James Morse <james.morse@....com>,
        Jamie Iles <quic_jiles@...cinc.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
        "patches@...ts.linux.dev" <patches@...ts.linux.dev>
Subject: RE: [PATCH v5 7/8] x86/resctrl: Update documentation with Sub-NUMA
 cluster changes

> How does user know Sub-NUMA Cluster mode is being enabled on the system?
>
> Do you have any information in /sys/fs/resctrl/info?
>
> Below documentation does not have any info about it.
> Would it be better to add that in "info" directory?


Babu,

My original patch series added an "snc_ways" file to the info/ directory
to make this visible. But I was talked out of it because of a lack of clear
user mode use case that needs it.

https://lore.kernel.org/all/f0841866-315b-4727-0a6c-ec60d22ca29c@arm.com/

Users can figure out whether SNC is enabled by looking at topology
files for nodes and L3 caches in /sys. The open question is whether
we should provide a simple short cut to that information, or make them
walk two miles uphill in the snow to figure it out.

-Tony