Re: [PATCH 04/16] mm: numa: Do not migrate or account for hinting faults on the zero page

Peter Zijlstra
2013-07-11T11:21:58Z

On Thu, Jul 11, 2013 at 10:46:48AM +0100, Mel Gorman wrote:
> +++ b/mm/memory.c
> @@ -3560,8 +3560,13 @@ int do_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
> set_pte_at(mm, addr, ptep, pte);
> update_mmu_cache(vma, addr, ptep);
>
> + /*
> + * Do not account for faults against the huge zero page. The read-only

s/huge //

> + * data is likely to be read-cached on the local CPUs and it is less
> + * useful to know about local versus remote hits on the zero page.
> + */
> page = vm_normal_page(vma, addr, pte);
> - if (!page) {
> + if (!page || is_zero_pfn(page_to_pfn(page))) {
> pte_unmap_unlock(ptep, ptl);
> return 0;
> }
> --
> 1.8.1.4
>