linux-kernel - Re: [PATCH V6 0/7] ACPI: Support Generic Initiator proximity domains

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Message-ID: <1867024e-b0c4-c291-7190-262cc4b297a8@gmail.com>
Date:   Fri, 20 Dec 2019 22:40:18 +0100
From:   Brice Goglin <brice.goglin@...il.com>
To:     Jonathan Cameron <Jonathan.Cameron@...wei.com>
Cc:     linux-mm@...ck.org, linux-acpi@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        x86@...nel.org, Keith Busch <kbusch@...nel.org>,
        jglisse@...hat.com, "Rafael J . Wysocki" <rjw@...ysocki.net>,
        linuxarm@...wei.com, Andrew Morton <akpm@...ux-foundation.org>,
        Dan Williams <dan.j.williams@...el.com>,
        Tao Xu <tao3.xu@...el.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Hanjun Guo <guohanjun@...wei.com>,
        Sudeep Holla <sudeep.holla@....com>
Subject: Re: [PATCH V6 0/7] ACPI: Support Generic Initiator proximity domains

Le 18/12/2019 à 15:50, Jonathan Cameron a écrit :
> On Wed, 18 Dec 2019 12:32:06 +0100
> Brice Goglin <brice.goglin@...il.com> wrote:
>
>> Le 16/12/2019 à 16:38, Jonathan Cameron a écrit :
>>> Introduces a new type of NUMA node for cases where we want to represent
>>> the access characteristics of a non CPU initiator of memory requests,
>>> as these differ from all those for existing nodes containing CPUs and/or
>>> memory.
>>>
>>> These Generic Initiators are presented by the node access0 class in
>>> sysfs in the same way as a CPU.   It seems likely that there will be
>>> usecases in which the best 'CPU' is desired and Generic Initiators
>>> should be ignored.  The final few patches in this series introduced
>>> access1 which is a new performance class in the sysfs node description
>>> which presents only CPU to memory relationships.  Test cases for this
>>> are described below.  
>>
>> Hello Jonathan
>>
>> If I want to test this with a fake GI, what are the minimal set of
>> changes I should put in my ACPI tables? Can I just specify a dummy GI in
>> SRAT? What handle should I use there?
> Exactly that for a dummy GI.  Also extend HMAT and SLIT for the extra
> proximity domain / initiator.


I couldn't get this to work (your patches on top of 5.5-rc2). I added
the GI in SRAT, and extended HMAT and SLIT accordingly.

I don't know if that's expected but I get an additional node in sysfs,
with 0kB memory.

However the HMAT table gets ignored because find_mem_target() fails in
hmat_parse_proximity_domain(). The target should have been allocated in
alloc_memory_target() which is called in srat_parse_mem_affinity(), but
it seems to me that this function isn't called for GI nodes. Or should
SRAT also contain a normal Memory node with same PM as the GI?

Brice