linux-kernel - Re: [RFC PATCH 00/20] x86/intel_rdt: Start abstraction for a second arch

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Message-ID: <378bfb14-df9c-bb89-8177-b4a5f6c7b226@arm.com>
Date:   Fri, 30 Nov 2018 19:23:38 +0000
From:   James Morse <james.morse@....com>
To:     Yury Norov <ynorov@...iumnetworks.com>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "x86@...nel.org" <x86@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Fenghua Yu <fenghua.yu@...el.com>,
        Tony Luck <tony.luck@...el.com>,
        Ingo Molnar <mingo@...hat.com>, H Peter Anvin <hpa@...or.com>,
        Reinette Chatre <reinette.chatre@...el.com>,
        Vikas Shivappa <vikas.shivappa@...ux.intel.com>,
        "Norov, Yuri" <Yuri.Norov@...ium.com>
Subject: Re: [RFC PATCH 00/20] x86/intel_rdt: Start abstraction for a second
 arch

Hi Yury,

On 27/11/2018 12:33, Yury Norov wrote:
> On Fri, Aug 24, 2018 at 11:44:59AM +0100, James Morse wrote:
>> ARM have some upcoming CPU features that are similar to Intel RDT. Resctrl
>> is the defacto ABI for this sort of thing, but it lives under arch/x86.
>>
>> To get existing software working, we need to make resctrl work with arm64.
>> This series is the first chunk of that. The aim is to move the filesystem/ABI
>> parts into /fs/resctrl, and implement a second arch backend.
>>
>>
>> What are the ARM features?
>> Future ARM SoCs may have a feature called MPAM: Memory Partitioning and
>> Monitoring. This is an umbrella term like RDT, and covers a range of controls
>> (like CAT) and monitors (like MBM, CMT).

>> This series is based on v4.18, and can be retrieved from:
>> git://linux-arm.org/linux-jm.git -b mpam/resctrl_rework/rfc_1
> 
> Thank you a lot for this work on cache allocation.
> 
> We are very interested in enabling CAT on Cavium / Marvell devices.
> Could you please share another two series you mentioned above?

I'm working on assembling the whole thing as Fenghua asked, there should be a
tree that shows the shape of the whole thing soon.


> Do you have a working ARM64 CAT driver? It will much help us in our
> experimenting.

For moving the arch-independent parts to /fs/, I'm afraid its all-or-nothing.
Abstracting just the 'CAT' parts will generate much more churn for both
architectures.


Thanks,

James