RE: Hugepages demand paging V1 [4/4]: Numa patch

[Chen, Kenneth W]

Christoph Lameter wrote on Thursday, October 21, 2004 9:59 PM
> Changelog
> 	* NUMA enhancements (rough first implementation)
> 	* Do not begin search for huge page memory at the first node
> 	  but start at the current node and then search previous and
> 	  the following nodes for memory.
>
> -static struct page *dequeue_huge_page(void)
> +static struct page *dequeue_huge_page(struct vm_area_struct *vma, unsigned long addr)
>  {
>  	int nid = numa_node_id();
> +	int tid, nid2;
>  	struct page *page = NULL;
>
>  	if (list_empty(&hugepage_freelists[nid])) {
> -		for (nid = 0; nid < MAX_NUMNODES; ++nid)
> -			if (!list_empty(&hugepage_freelists[nid]))
> -				break;
> +		/* Prefer the neighboring nodes */
> +		for (tid =1 ; tid < MAX_NUMNODES; tid++) {
> +
> +			/* Is there space in a following node ? */
> +			nid2 = (nid + tid) % MAX_NUMNODES;
> +			if (mpol_node_valid(nid2, vma, addr) &&
> +				!list_empty(&hugepage_freelists[nid2]))
> +					break;
> +
> +			/* or in an previous node ? */
> +			if (tid > nid) continue;
> +			nid2 = nid - tid;
> +			if (mpol_node_valid(nid2, vma, addr) &&
> +				!list_empty(&hugepage_freelists[nid2]))
> +					break;

Are you sure about this?  Looked flawed to me.  Logical node number
does not directly correlate to numa memory hierarchy.

- Ken


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