linux-kernel - Re: [PATCH 01/18] x86/resctrl: Track the closid with the rmid

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Date:   Mon, 31 Oct 2022 15:42:50 +0100
From:   Peter Newman <peternewman@...gle.com>
To:     James Morse <james.morse@....com>
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org,
        Fenghua Yu <fenghua.yu@...el.com>,
        Reinette Chatre <reinette.chatre@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        H Peter Anvin <hpa@...or.com>,
        Babu Moger <Babu.Moger@....com>,
        shameerali.kolothum.thodi@...wei.com,
        D Scott Phillips OS <scott@...amperecomputing.com>,
        carl@...amperecomputing.com, lcherian@...vell.com,
        bobo.shaobowang@...wei.com, tan.shaopeng@...itsu.com,
        Jamie Iles <quic_jiles@...cinc.com>,
        Xin Hao <xhao@...ux.alibaba.com>, xingxin.hx@...nanolis.org,
        baolin.wang@...ux.alibaba.com
Subject: Re: [PATCH 01/18] x86/resctrl: Track the closid with the rmid

Hi James,

On Fri, Oct 21, 2022 at 3:12 PM James Morse <james.morse@....com> wrote:
>
> x86's RMID are independent of the CLOSID. An RMID can be allocated,
> used and freed without considering the CLOSID.
>
> MPAM's equivalent feature is PMG, which is not an independent number,
> it extends the CLOSID/PARTID space. For MPAM, only PMG-bits worth of
> 'RMID' can be allocated for a single CLOSID.
> i.e. if there is 1 bit of PMG space, then each CLOSID can have two
> monitor groups.
>
> To allow rescrl to disambiguate RMID values for different CLOSID,
> everything in resctrl that keeps an RMID value needs to know the CLOSID
> too. This will always be ignored on x86.

I recall that the allocation of RMIDs on MPAM was an open topic of
discussion on the other thread. Can we finish that discussion first?

https://lore.kernel.org/lkml/14df28f0-90b1-9c43-add5-08947165596d@intel.com/

Thanks!
-Peter