Re: [Xen-devel] [RFC PATCH v2 09/25] ARM: NUMA: Add existing ARM numa code under CONFIG_NUMA

[Vijay Kilari <vijay.kilari@xxxxxxxxx>]

On Mon, May 8, 2017 at 9:28 PM, Julien Grall <julien.grall@xxxxxxx> wrote:
> Hi Vijay,
>
> On 28/03/17 16:53, vijay.kilari@xxxxxxxxx wrote:
>>
>> From: Vijaya Kumar K <Vijaya.Kumar@xxxxxxxxxx>
>>
>> Right now CONFIG_NUMA is not enabled for ARM and
>> existing code in asm-arm/numa.h is for !CONFIG_NUMA.
>> Hence put this code under #ifndef CONFIG_NUMA.
>>
>> This help to make this changes work when CONFIG_NUMA
>> is not enabled.
>
>
> But you always turn NUMA on by default (see patch #24) and there is no
> possibility to turn off NUMA.

Yes at the end of the series we enable NUMA by default.
But the the intermittent patches of this patch series fails to compile.

>
>>
>> Also define NODES_SHIFT macro for ARM to value 2.
>> This limits number of NUMA nodes supported to 4.
>> There is not hard restrictions on this value set to 2.
>
>
> Again, why only 2 when x86 is supporting 6?
>
> Furthermore, this is not related to this patch itself and should be part of
> separate patch.
>
> Lastly, why don't you move that to a Kconfig allowing the user to configure
> the number of Nodes?

ok

>
>>
>> Signed-off-by: Vijaya Kumar K <Vijaya.Kumar@xxxxxxxxxx>
>> ---
>>  xen/include/asm-arm/numa.h | 5 +++++
>>  1 file changed, 5 insertions(+)
>>
>> diff --git a/xen/include/asm-arm/numa.h b/xen/include/asm-arm/numa.h
>> index 53f99af..924bfc0 100644
>> --- a/xen/include/asm-arm/numa.h
>> +++ b/xen/include/asm-arm/numa.h
>> @@ -3,6 +3,10 @@
>>
>>  typedef uint8_t nodeid_t;
>>
>> +/* Limit number of NUMA nodes supported to 4 */
>> +#define NODES_SHIFT 2
>
>
> Why this is not covered by CONFIG_NUMA?

The below define is used in generic code irrespective of CONFIG_NUMA

#define MAX_NUMNODES    (1 << NODES_SHIFT)

>
>> +
>> +#ifndef CONFIG_NUMA
>>  /* Fake one node for now. See also node_online_map. */
>>  #define cpu_to_node(cpu) 0
>>  #define node_to_cpumask(node)   (cpu_online_map)
>> @@ -16,6 +20,7 @@ static inline __attribute__((pure)) nodeid_t
>> phys_to_nid(paddr_t addr)
>>  #define node_spanned_pages(nid) (total_pages)
>>  #define node_start_pfn(nid) (pdx_to_pfn(frametable_base_pdx))
>>  #define __node_distance(a, b) (20)
>> +#endif /* CONFIG_NUMA */
>>
>>  static inline unsigned int arch_get_dma_bitsize(void)
>>  {
>>
>
> Cheers,
>
> --
> Julien Grall

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