linux-kernel - Re: [PATCH v3 15/19] x86/resctrl: Add helpers for system wide mon/alloc capable

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Message-ID: <bda01f60-e6fc-1c30-ba54-45abcbbc8e0a@arm.com>
Date:   Thu, 27 Apr 2023 15:19:47 +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
Subject: Re: [PATCH v3 15/19] x86/resctrl: Add helpers for system wide
 mon/alloc capable

On 01/04/2023 00:29, Reinette Chatre wrote:
> Hi James,
> 
> On 3/20/2023 10:26 AM, 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.
> 
> hmmm ... they are not the same though since the static-keys
> in addition means that resctrl is mounted.

and all the paths where this matters were updated in patch 12 to have an explicit
resctrl_mounted check.


Thanks,

James