On Thu, Oct 04, 2012 at 01:51:05AM +0200, Andrea Arcangeli wrote:
> When pages are collapsed try to keep the last_nid information from one
> of the original pages.
>
If two pages within a THP disagree on the node, should the collapsing be
aborted? I would expect that the code of a remote access exceeds the
gain from reduced TLB overhead.
> Signed-off-by: Andrea Arcangeli <aarcange@xxxxxxxxxx>
> ---
> mm/huge_memory.c | 14 ++++++++++++++
> 1 files changed, 14 insertions(+), 0 deletions(-)
>
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 1023e67..78b2851 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -1846,6 +1846,9 @@ static bool __collapse_huge_page_copy(pte_t *pte, struct page *page,
> {
> pte_t *_pte;
> bool mknuma = false;
> +#ifdef CONFIG_AUTONUMA
> + int autonuma_last_nid = -1;
> +#endif
> for (_pte = pte; _pte < pte+HPAGE_PMD_NR; _pte++) {
> pte_t pteval = *_pte;
> struct page *src_page;
> @@ -1855,6 +1858,17 @@ static bool __collapse_huge_page_copy(pte_t *pte, struct page *page,
> add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1);
> } else {
> src_page = pte_page(pteval);
> +#ifdef CONFIG_AUTONUMA
> + /* pick the first one, better than nothing */
> + if (autonuma_last_nid < 0) {
> + autonuma_last_nid =
> + ACCESS_ONCE(src_page->
> + autonuma_last_nid);
> + if (autonuma_last_nid >= 0)
> + ACCESS_ONCE(page->autonuma_last_nid) =
> + autonuma_last_nid;
> + }
> +#endif
> copy_user_highpage(page, src_page, address, vma);
> VM_BUG_ON(page_mapcount(src_page) != 1);
> release_pte_page(src_page);
>
--
Mel Gorman
SUSE Labs
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