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

[thunder.leizhen@huawei.com (Leizhen (ThunderTown))]

On 2015/9/11 11:53, Ganapatrao Kulkarni wrote:
> Hi Thunder,
> 
> 
> On Tue, Sep 8, 2015 at 9:57 PM, Ganapatrao Kulkarni
> <gpkulkarni@gmail.com> wrote:
>> Hi Hanjun,
>>
>> On Tue, Sep 8, 2015 at 6:57 PM, Hanjun Guo <hanjun.guo@linaro.org> wrote:
>>> Hi Ganapatrao,
>>>
>>>
>>> On 08/29/2015 10:56 PM, Ganapatrao Kulkarni wrote:
>>>>
>>>> Hi Thunder,
>>>>
>>>> On Sat, Aug 29, 2015 at 3:16 PM, Leizhen (ThunderTown)
>>>> <thunder.leizhen@huawei.com> wrote:
>>>>>
>>>>>
>>>>>
>>>>> On 2015/8/28 22:02, Rob Herring wrote:
>>>>>>
>>>>>> +benh
>>>>>>
>>>>>> On Fri, Aug 28, 2015 at 7:32 AM, Mark Rutland <mark.rutland@arm.com>
>>>>>> wrote:
>>>>>>>
>>>>>>> Hi,
>>>>>>>
>>>>>>> On Fri, Aug 14, 2015 at 05:39:32PM +0100, Ganapatrao Kulkarni wrote:
>>>>>>>>
>>>>>>>> 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.


>>>>>
>>>>> 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!
>>>
>>>> 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.
>>>
>>> Thanks
>>> Hanjun
>>
>> thanks
>> Ganapat
> thanks
> Ganapat
> 
> .
>