linux-kernel - Re: [EXT] Re: resctrl2

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Message-ID: <6682c765-9d7f-dd21-af85-e83cee435a89@arm.com>
Date:   Fri, 15 Sep 2023 18:16:43 +0100
From:   James Morse <james.morse@....com>
To:     Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        Amit Singh Tomar <amitsinght@...vell.com>
Cc:     Reinette Chatre <reinette.chatre@...el.com>,
        "Luck, Tony" <tony.luck@...el.com>,
        "Yu, Fenghua" <fenghua.yu@...el.com>,
        George Cherian <gcherian@...vell.com>,
        "robh@...nel.org" <robh@...nel.org>,
        "peternewman@...gle.com" <peternewman@...gle.com>,
        Drew Fustini <dfustini@...libre.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [EXT] Re: resctrl2 - status

Hi guys,

On 30/08/2023 11:47, Jonathan Cameron wrote:
> On Tue, 29 Aug 2023 17:18:53 +0000
> Amit Singh Tomar <amitsinght@...vell.com> wrote:
>> From: Jonathan Cameron <Jonathan.Cameron@...wei.com> 
>> James probably also has views on this, but I wouldn't expect userspace to go anywhere near ACPI parsing.

I agree wholeheartedly! Parsing the ACPI tables also wouldn't work: the firmware tables
describe where the MPAM hardware is, but the features that are supported are described by
the hardware, then grouped to find the common features we can make use of.


>> If the description of what MPAM features are supported (before resctrl is running) is necessary, then we
>> should add it to the existing description of the various caches etc.  Maybe somewhere in
>> /sys/bus/node/devices/nodeX/cpuY/cache/indexZ/

>> for the caches
>> and
>> /sys/bus/node/devices/nodeX for the DRAM controllers.

>> [>>] Or may be all the MPAM features list is unified at one place, something like this ?  
>> https://git.kernel.org/pub/scm/linux/kernel/git/morse/linux.git/commit/?h=mpam/snapshot/v6.5-rc1&id=c32874cd1d68241c481a9d0c32c8c65d019c247e
> 
> Fine for debug, not for generic tooling.

Yeah, this is really just for folk reporting bugs to me so we can work out what their
firmware table described, and what the driver found.


Thanks,

James