[PATCH v5 2/4] Documentation: arm64/arm: dt bindings for numa.

On 2015/9/11 11:53, Ganapatrao Kulkarni wrote:

Hi Thunder,


On Tue, Sep 8, 2015 at 9:57 PM, Ganapatrao Kulkarni
[off-list ref] wrote:

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Hi Hanjun,

On Tue, Sep 8, 2015 at 6:57 PM, Hanjun Guo [off-list ref] wrote:

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Hi Ganapatrao,


On 08/29/2015 10:56 PM, Ganapatrao Kulkarni wrote:

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Hi Thunder,

On Sat, Aug 29, 2015 at 3:16 PM, Leizhen (ThunderTown)
[off-list ref] wrote:

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On 2015/8/28 22:02, Rob Herring wrote:

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+benh

On Fri, Aug 28, 2015 at 7:32 AM, Mark Rutland [off-list ref]
wrote:

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Hi,

On Fri, Aug 14, 2015 at 05:39:32PM +0100, Ganapatrao Kulkarni wrote:

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DT bindings for numa map for memory, cores and IOs using
arm,associativity device node property.

Given this is just a copy of ibm,associativity, I'm not sure I see much
point in renaming the properties.

So just keep the ibm? I'm okay with that. That would help move to
common code. Alternatively, we could drop the vendor prefix and have
common code just check for both.

Hi all,

Why not copy the method of ACPI numa? There only three elements should be
configured:
1) a cpu belong to which node
2) a memory block belong to which node
3) the distance of each two nodes

I too thought acpi only defines mapping for cpu and memory to numa
nodes and no specification to define for IOs.
however after going through the x86 implementation, i can see there is
provision for mapping IOs to numa node in acpi.
in x86 code, function pci_acpi_scan_root calls acpi_get_node to get
associated node for pci bus using _PXM object.
it imply there is entry in acpi tables to map pci bus for numa
node(proximity domain).
so in dt also, we should  have binding to define cpu, memory and IOs
to node mapping.

Yes, we should implement of_node_to_nid, to support device driver use dev_to_node.

I have added description about it, in the reply to Benjamin Herrenschmidt, at 2015/8/31 9:46.

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The devicetree nodes of numa can be like below:
/ {
         ...

         numa-nodes-info {
                 node-name: node-description {
                         mem-ranges = <...>;
                         cpus-list = <...>;
                 };

                 nodes-distance {
                         distance-list = <...>;
                 };
         };

         ...
};

some what similar to what your are proposing is already implemented in
my v2 patchset.
https://lwn.net/Articles/623920/

http://lists.infradead.org/pipermail/linux-arm-kernel/2014-November/305164.html
we have went to associativity property based implementation to keep it
more generic.
i do have both acpi(using linaro/hanjun's patches) and associativity
based implementations on our internal tree
and tested on thunderx platform.

Great thanks!

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i do see issue in creating numa mapping using ACPI for IOs(for
example, i am not able to create numa mapping for ITS which is on each
node, using ACPI tables),  since ACPI spec (tables SRAT and SLIT)
talks only about processor and memory.

I'm not sure why the ITS needs to know the NUMA domain, for my
understanding, the interrupt will route to the correct NUMA domain
using setting the affinity, ITS will configured to route it to
the right GICR(cpu), so I think the ITS don't need to know which
NUMA node belonging to, correct me if I missed something.

IIUC, GICR/collection is per cpu and can be mapped to numa node using
cpu to node mapping.
However there are multiple its in multi-socket platform(at-least one
its per socket),
knowing its to numa node mapping will help in routing(optimal) the
interrupts to  any one of GICR/collections of that node
Hence, we need to find which its belongs to which socket/node using dt.
same applies to pci bus too.

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Thanks
Hanjun

thanks
Ganapat

thanks
Ganapat

.