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

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Message-ID: <b428d231-4879-4462-ac42-900b5d094eee@gmail.com>
Date:   Thu, 2 Jan 2020 22:37:04 +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 02/01/2020 à 16:27, Jonathan Cameron a écrit :
>
>> 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?
>>
> Hi Brice,
>
> Yes you should see a node with 0kB memory.  Same as you get for a processor
> only node I believe.
>
> srat_parse_mem_affinity shouldn't call alloc_memory_target for the GI nodes
> as they don't have any memory.   The hmat table should only refer to
> GI domains as initiators.  Just to check, do you have them listed as
> a target node?  Or perhaps in some hmat proximity entry as memory_PD?
>

Thanks, I finally got things to work. I am on x86. It's a dual-socket
machine with SubNUMA clusters (2 nodes per socket) and NVDIMMs (one
dax-kmem node per socket). Before adding a GI, initiators look like this:

node0 -> node0 and node4

node1 -> node1 and node5

node2 -> node2 and node4

node3 -> node3 and node5

I added a GI with faster access to node0, node2, node4 (first socket).

The GI node becomes an access0 initiator for node4, and node0 and node2
remain access1 initiators.

The GI node doesn't become access0 initiator for node0 and node2, likely
because of this test :

        /*
         * If the Address Range Structure provides a local processor pxm, link
         * only that one. Otherwise, find the best performance attributes and
         * register all initiators that match.
         */
        if (target->processor_pxm != PXM_INVAL) {

I guess I should split node0-3 into separate CPU nodes and memory nodes
in SRAT?

Brice