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

[Julien Grall <julien.grall@arm.com>]

Hi Vijay,

On 28/03/17 16:53, vijay.kilari@gmail.com wrote:
> From: Vijaya Kumar K <Vijaya.Kumar@cavium.com>
>
> 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.

>
> 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?

>
> Signed-off-by: Vijaya Kumar K <Vijaya.Kumar@cavium.com>
> ---
>  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?

> +
> +#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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