linux-kernel - Re: [PATCH v8 10/24] x86/resctrl: Allocate the cleanest CLOSID by searching closid_num_dirty

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Message-ID: <9d30c56a-a772-c121-ca02-f3f237f0a892@arm.com>
Date: Mon, 22 Jan 2024 18:06:12 +0000
From: James Morse <james.morse@....com>
To: Reinette Chatre <reinette.chatre@...el.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 v8 10/24] x86/resctrl: Allocate the cleanest CLOSID by
 searching closid_num_dirty_rmid

Hi Reinette,

On 16/12/2023 05:01, Reinette Chatre wrote:
> On 12/15/2023 9:43 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.


> (This is an example of me not relying on you dropping my reviewed-by tag
> to take a look at new changes.)

Significant changes. This is only the expected behaviour when significant changes are made
to a patch. This is a comment - and the text of the comment isn't changed.


> This change is unexpected and does not have anything to do with this patch.
> Instead it just seems to undo a change that sneaked into patch #8
> of this series.

Thanks - I was misled by closid_num_dirty_rmid existing before the patch with its name in
the subject. I'll fix this.


Thanks,

James