linux-kernel - Re: [PATCH v7 10/24] x86/resctrl: Allocate the cleanest CLOSID by searching closid_num_dirty

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Date:   Thu, 9 Nov 2023 09:46:16 -0800
From:   Reinette Chatre <reinette.chatre@...el.com>
To:     James Morse <james.morse@....com>, <x86@...nel.org>,
        <linux-kernel@...r.kernel.org>
CC:     Fenghua Yu <fenghua.yu@...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>,
        <baolin.wang@...ux.alibaba.com>,
        Jamie Iles <quic_jiles@...cinc.com>,
        Xin Hao <xhao@...ux.alibaba.com>, <peternewman@...gle.com>,
        <dfustini@...libre.com>, <amitsinght@...vell.com>
Subject: Re: [PATCH v7 10/24] x86/resctrl: Allocate the cleanest CLOSID by
 searching closid_num_dirty_rmid

Hi James,

On 10/25/2023 11:03 AM, James Morse wrote:
> MPAM's PMG bits extend its PARTID space, meaning the same PMG value can be
> used for different control groups.
> 
> This means once a CLOSID is allocated, all its monitoring ids may still be
> dirty, and held in limbo.
> 
> Instead of allocating the first free CLOSID, on architectures where
> CONFIG_RESCTRL_RMID_DEPENDS_ON_CLOSID is enabled, search
> closid_num_dirty_rmid[] to find the cleanest CLOSID.
> 
> The CLOSID found is returned to closid_alloc() for the free list
> to be updated.
> 
> Tested-by: Shaopeng Tan <tan.shaopeng@...itsu.com>
> Tested-by: Peter Newman <peternewman@...gle.com>
> Reviewed-by: Shaopeng Tan <tan.shaopeng@...itsu.com>
> Reviewed-by: Reinette Chatre <reinette.chatre@...el.com>
> Signed-off-by: James Morse <james.morse@....com>
> ---
> Changes since v4:
>  * Dropped stale section from comment
> 
> Changes since v5:
>  * Renamed some variables.
> 
> No changes since v6

I use these patch changelogs to determine if I need to look at a
patch for which I already provided a review tag. At first this
patch appears to not deserve a second glance because I already provided a
review tag and the above states "No changes since v6". Unfortunately
this is false. I counted four changes. Now I cannot trust these
"No changes since v6" and I need to dig out v6 to diff patches I already
reviewed to determine if I need to look at them again. False patch
changelogs make a patch series harder to review.

Reinette