Re: [PATCH v2 1/3] x86/numa: Allow arbitrary value of PXM in PXM<->node mapping

[Boris Ostrovsky <boris.ostrovsky@oracle.com>]

On 02/25/2015 04:34 AM, Jan Beulich wrote:
>>>> On 24.02.15 at 20:11, <boris.ostrovsky@oracle.com> wrote:
>> --- a/xen/arch/x86/srat.c
>> +++ b/xen/arch/x86/srat.c
>> @@ -27,35 +27,79 @@ static nodemask_t memory_nodes_parsed __initdata;
>>   static nodemask_t processor_nodes_parsed __initdata;
>>   static nodemask_t nodes_found __initdata;
>>   static struct node nodes[MAX_NUMNODES] __initdata;
>> -static u8 __read_mostly pxm2node[256] = { [0 ... 255] = NUMA_NO_NODE };
>>   
>> +struct pxm2node {
>> +    unsigned pxm;
>> +    int node;
>> +};
>> +static struct pxm2node __read_mostly p2n[MAX_NUMNODES] =
> Can this please continue to be named pxm2node[]? "p2..." is too
> commonly used for representing a phys-to-something conversion.
>
>> +    { [0 ... MAX_NUMNODES - 1] = {.node = NUMA_NO_NODE} };
>> +
>> +static int node_to_pxm(int n);
> I don't see why you need to reinstate this forward declaration.

It is used in acpi_numa_memory_affinity_init() which is defined above 
node_to_pxm().

I can just move node_to_pxm() definition higher and drop forward 
declaration.

>
>>   int pxm_to_node(int pxm)
>>   {
>> -	if ((unsigned)pxm >= 256)
>> -		return -1;
>> -	/* Extend 0xff to (int)-1 */
>> -	return (signed char)pxm2node[pxm];
>> +    unsigned i;
>> +
>> +    if ( (pxm < MAX_NUMNODES) && node_found(pxm, pxm) )
>> +        return p2n[pxm].node;
> With this the function parameter's type can't remain to be signed.

Right. I was hoping to defer all type changes to the next patch but this 
(and setup_node() below) will need to change here.

-boris

> Also please don't change coding style here, unless you do so for
> the whole file (in a separate patch). The one change I wouldn't
> mind is switching node_to_pxm() from 8-space to tab indentation.
>
>>   __devinit int setup_node(int pxm)
>>   {
>> -	unsigned node = pxm2node[pxm];
>> -	if (node == 0xff) {
>> -		if (nodes_weight(nodes_found) >= MAX_NUMNODES)
>> -			return -1;
>> -		node = first_unset_node(nodes_found);
>> -		node_set(node, nodes_found);
>> -		pxm2node[pxm] = node;
>> -	}
>> -	return pxm2node[pxm];
>> +    int node;
>> +    unsigned idx;
>> +    static bool_t warned;
>> +
>> +    if ( pxm < MAX_NUMNODES )
>> +    {
>> +        if ( node_found(pxm, pxm) )
>> +            return p2n[pxm].node;