linux-kernel - Re: [PATCH v8 19/24] x86/resctrl: Add helpers for system wide mon/alloc capable

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Date: Mon, 22 Jan 2024 18:06:27 +0000
From: James Morse <james.morse@....com>
To: babu.moger@....com, x86@...nel.org, linux-kernel@...r.kernel.org
Cc: 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>,
 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 19/24] x86/resctrl: Add helpers for system wide
 mon/alloc capable

Hi Babu,

On 03/01/2024 19:43, Moger, Babu wrote:
> On 12/15/23 11:43, James Morse wrote:
>> resctrl reads rdt_alloc_capable or rdt_mon_capable to determine
>> whether any of the resources support the corresponding features.
>> resctrl also uses the static-keys that affect the architecture's
>> context-switch code to determine the same thing.
>>
>> This forces another architecture to have the same static-keys.
>>
>> As the static-key is enabled based on the capable flag, and none of
>> the filesystem uses of these are in the scheduler path, move the
>> capable flags behind helpers, and use these in the filesystem
>> code instead of the static-key.
>>
>> After this change, only the architecture code manages and uses
>> the static-keys to ensure __resctrl_sched_in() does not need
>> runtime checks.
>>
>> This avoids multiple architectures having to define the same
>> static-keys.
>>
>> Cases where the static-key implicitly tested if the resctrl
>> filesystem was mounted all have an explicit check added by a
>> previous patch.

> Reviewed-by: Babu Moger <babu.moger@....com>


Thanks!

James