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

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

On 02/25/2015 04:34 AM, Jan Beulich wrote:
> > > > On 24.02.15 at 20:11, <boris.ostrovsky@xxxxxxxxxx> 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;

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