linux-kernel - Re: [PATCH 03/18] mm: numa: Account for THP numa hinting faults on the correct node

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Date:	Wed, 17 Jul 2013 08:33:13 +0800
From:	Hillf Danton <dhillf@...il.com>
To:	Mel Gorman <mgorman@...e.de>
Cc:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
	Ingo Molnar <mingo@...nel.org>,
	Andrea Arcangeli <aarcange@...hat.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Linux-MM <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 03/18] mm: numa: Account for THP numa hinting faults on
 the correct node

On Mon, Jul 15, 2013 at 11:20 PM, Mel Gorman <mgorman@...e.de> wrote:
> THP NUMA hinting fault on pages that are not migrated are being
> accounted for incorrectly. Currently the fault will be counted as if the
> task was running on a node local to the page which is not necessarily
> true.
>
Can you please run test again without this correction and check the difference?

> Signed-off-by: Mel Gorman <mgorman@...e.de>
> ---
>  mm/huge_memory.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index e2f7f5aa..e4a79fa 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -1293,7 +1293,7 @@ int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
>         struct page *page;
>         unsigned long haddr = addr & HPAGE_PMD_MASK;
>         int target_nid;
> -       int current_nid = -1;
> +       int src_nid = -1;
>         bool migrated;
>
>         spin_lock(&mm->page_table_lock);
> @@ -1302,9 +1302,9 @@ int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
>
>         page = pmd_page(pmd);
>         get_page(page);
> -       current_nid = page_to_nid(page);
> +       src_nid = numa_node_id();
>         count_vm_numa_event(NUMA_HINT_FAULTS);
> -       if (current_nid == numa_node_id())
> +       if (src_nid == page_to_nid(page))
>                 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
>
>         target_nid = mpol_misplaced(page, vma, haddr);
> @@ -1346,8 +1346,8 @@ clear_pmdnuma:
>         update_mmu_cache_pmd(vma, addr, pmdp);
>  out_unlock:
>         spin_unlock(&mm->page_table_lock);
> -       if (current_nid != -1)
> -               task_numa_fault(current_nid, HPAGE_PMD_NR, false);
> +       if (src_nid != -1)
> +               task_numa_fault(src_nid, HPAGE_PMD_NR, false);
>         return 0;
>  }
--
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