linux-kernel - Re: [PATCH v3 5/8] x86/resctrl: Add package scoped resource

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Date:   Tue, 18 Jul 2023 16:05:26 -0700
From:   Tony Luck <tony.luck@...el.com>
To:     Reinette Chatre <reinette.chatre@...el.com>
Cc:     Fenghua Yu <fenghua.yu@...el.com>,
        Peter Newman <peternewman@...gle.com>,
        Jonathan Corbet <corbet@....net>,
        Shuah Khan <skhan@...uxfoundation.org>, x86@...nel.org,
        Shaopeng Tan <tan.shaopeng@...itsu.com>,
        James Morse <james.morse@....com>,
        Jamie Iles <quic_jiles@...cinc.com>,
        Babu Moger <babu.moger@....com>,
        Randy Dunlap <rdunlap@...radead.org>,
        linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
        patches@...ts.linux.dev
Subject: Re: [PATCH v3 5/8] x86/resctrl: Add package scoped resource

On Tue, Jul 18, 2023 at 01:43:45PM -0700, Reinette Chatre wrote:
> Hi Tony,
> 
> On 7/13/2023 9:32 AM, Tony Luck wrote:
> > Some Intel features require setting a package scoped model specific
> > register.
> > 
> > Add a new resource that builds domains for each package.
> 
> If I understand correctly the only purpose of this new resource
> is to know when the first CPU associated with a package
> comes online. Am I not reading this right? Using a resctrl resource
> for this purpose seems inappropriate and unnecessary while also
> making the code very hard to follow.

Reinette,

Yes. You understand.

I agree that this is blatant abuse of the resource structures.  I can find
another way to perform an action on the first CPU of a package online,
and the last CPU of a package offline.

-Tony