On (09/11/07 07:45), Christoph Lameter didst pronounce:
> On Fri, 9 Nov 2007, Mel Gorman wrote:
>
> > struct page * fastcall
> > __alloc_pages(gfp_t gfp_mask, unsigned int order,
> > struct zonelist *zonelist)
> > {
> > + /*
> > + * Use a temporary nodemask for __GFP_THISNODE allocations. If the
> > + * cost of allocating on the stack or the stack usage becomes
> > + * noticable, allocate the nodemasks per node at boot or compile time
> > + */
> > + if (unlikely(gfp_mask & __GFP_THISNODE)) {
> > + nodemask_t nodemask;
>
> Hmmm.. This places a potentially big structure on the stack. nodemask can
> contain up to 1024 bits which means 128 bytes. Maybe keep an array of
> gfp_thisnode nodemasks (node_nodemask?) and use node_nodemask[nid]?
>
That is what I was hinting at in the comment as a possible solution.
> > +
> > + return __alloc_pages_internal(gfp_mask, order,
> > + zonelist, nodemask_thisnode(numa_node_id(), &nodemask));
>
> Argh.... GFP_THISNODE must use the nid passed to alloc_pages_node and
> *not* the local numa node id. Only if the node specified to alloc_pages
> nodes is -1 will this work.
>
alloc_pages_node() calls __alloc_pages_nodemask() though where in this
function if I'm reading it right is called without a node id. Given no
other details on the nid, the current one seemed a logical choice.
What I did notice when rechecking is I left the warning about THISNODE
in by accident :(
--
--
Mel Gorman
Part-time Phd Student Linux Technology Center
University of Limerick IBM Dublin Software Lab
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