linux-kernel - Re: [PATCH v6 22/24] x86/resctrl: Add cpu offline callback for resctrl work

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Date:   Wed, 25 Oct 2023 18:57:42 +0100
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,
        xingxin.hx@...nanolis.org, 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 v6 22/24] x86/resctrl: Add cpu offline callback for
 resctrl work

Hi Reinette,

On 03/10/2023 22:23, Reinette Chatre wrote:
> On 9/14/2023 10:21 AM, James Morse wrote:
>> The resctrl architecture specific code may need to free a domain when
>> a CPU goes offline, it also needs to reset the CPUs PQR_ASSOC register.
>> Amongst other things, the resctrl filesystem code needs to clear this
>> CPU from the cpu_mask of any control and monitor groups.
>>
>> Currently this is all done in core.c and called from
>> resctrl_offline_cpu(), making the split between architecture and
>> filesystem code unclear.
>>
>> Move the filesystem work to remove the CPU from the control and monitor
>> groups into a filesystem helper called resctrl_offline_cpu(), and rename
>> the one in core.c resctrl_arch_offline_cpu().
>>
>> The rdtgroup_mutex is unlocked and locked again in the call in
>> preparation for changing the locking rules for the architecture
>> code.
> 
> This last paragraph may cause some confusion since this refactoring
> is not changing any current locking. I'll defer to you if you prefer
> to keep it.

Hmm, that is referring to an earlier version that looked funny and I felt needed
explanation. I've remove that paragraph.


>> Reviewed-by: Shaopeng Tan <tan.shaopeng@...itsu.com>
>> Tested-by: Shaopeng Tan <tan.shaopeng@...itsu.com>
>> Tested-By: Peter Newman <peternewman@...gle.com>
>> Signed-off-by: James Morse <james.morse@....com>
>> ---
> 
> Reviewed-by: Reinette Chatre <reinette.chatre@...el.com>


Thanks!

James