Re: [Xen-devel] [PATCH 1/2] page-alloc/x86: don't restrict DMA heap to node 0

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 10/08/16 10:23, Jan Beulich wrote:
> --- a/xen/arch/x86/numa.c
> +++ b/xen/arch/x86/numa.c
> @@ -355,11 +355,21 @@ void __init init_cpu_to_node(void)
>      }
>  }
>  
> -EXPORT_SYMBOL(cpu_to_node);
> -EXPORT_SYMBOL(node_to_cpumask);
> -EXPORT_SYMBOL(memnode_shift);
> -EXPORT_SYMBOL(memnodemap);
> -EXPORT_SYMBOL(node_data);
> +unsigned int __init arch_get_dma_bitsize(void)
> +{
> +    unsigned int node;
> +
> +    for_each_online_node(node)
> +        if ( node_spanned_pages(node) &&
> +             !(node_start_pfn(node) >> (32 - PAGE_SHIFT)) )
> +            break;
> +    if ( node >= MAX_NUMNODES )
> +        panic("No node with memory below 4Gb");
> +
> +    return min_t(unsigned int,
> +                 flsl(node_start_pfn(node) + node_spanned_pages(node) / 4 - 
> 1)
> +                 + PAGE_SHIFT, 32);

You have moved the -1 and -2 inside the flsl() call, which alters its
behaviour quite a bit.  Is this intentional or accidental?

~Andrew

> +}
>  
>  static void dump_numa(unsigned char key)
>  {
> --- a/xen/common/page_alloc.c
> +++ b/xen/common/page_alloc.c
> @@ -1368,16 +1368,7 @@ void __init end_boot_allocator(void)
>      init_heap_pages(virt_to_page(bootmem_region_list), 1);
>  
>      if ( !dma_bitsize && (num_online_nodes() > 1) )
> -    {
> -#ifdef CONFIG_X86
> -        dma_bitsize = min_t(unsigned int,
> -                            flsl(NODE_DATA(0)->node_spanned_pages) - 1
> -                            + PAGE_SHIFT - 2,
> -                            32);
> -#else
> -        dma_bitsize = 32;
> -#endif
> -    }
> +        dma_bitsize = arch_get_dma_bitsize();
>  
>      printk("Domain heap initialised");
>      if ( dma_bitsize )


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