On 05/23/2018 05:58 PM, Huang, Ying wrote:
> From: Huang Ying <ying.huang@xxxxxxxxx>
>
> This is to take better advantage of the general huge page copying
> optimization. Where, the target subpage will be copied last to avoid
> the cache lines of target subpage to be evicted when copying other
> subpages. This works better if the address of the target subpage is
> available when copying huge page. So hugetlbfs page fault handlers
> are changed to pass that information to hugetlb_cow(). This will
> benefit workloads which don't access the begin of the hugetlbfs huge
> page after the page fault under heavy cache contention.
>
> Signed-off-by: "Huang, Ying" <ying.huang@xxxxxxxxx>
Reviewed-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
--
Mike Kravetz
> Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
> Cc: Michal Hocko <mhocko@xxxxxxxx>
> Cc: David Rientjes <rientjes@xxxxxxxxxx>
> Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
> Cc: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
> Cc: Andi Kleen <andi.kleen@xxxxxxxxx>
> Cc: Jan Kara <jack@xxxxxxx>
> Cc: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>
> Cc: Hugh Dickins <hughd@xxxxxxxxxx>
> Cc: Minchan Kim <minchan@xxxxxxxxxx>
> Cc: Shaohua Li <shli@xxxxxx>
> Cc: Christopher Lameter <cl@xxxxxxxxx>
> Cc: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
> Cc: Punit Agrawal <punit.agrawal@xxxxxxx>
> Cc: Anshuman Khandual <khandual@xxxxxxxxxxxxxxxxxx>
> ---
> mm/hugetlb.c | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index ad3bec2ed269..1df974af34c1 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -3500,7 +3500,7 @@ static void unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma,
> * Keep the pte_same checks anyway to make transition from the mutex easier.
> */
> static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
> - unsigned long haddr, pte_t *ptep,
> + unsigned long address, pte_t *ptep,
> struct page *pagecache_page, spinlock_t *ptl)
> {
> pte_t pte;
> @@ -3509,6 +3509,7 @@ static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
> int ret = 0, outside_reserve = 0;
> unsigned long mmun_start; /* For mmu_notifiers */
> unsigned long mmun_end; /* For mmu_notifiers */
> + unsigned long haddr = address & huge_page_mask(h);
>
> pte = huge_ptep_get(ptep);
> old_page = pte_page(pte);
> @@ -3583,7 +3584,7 @@ static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
> goto out_release_all;
> }
>
> - copy_user_huge_page(new_page, old_page, haddr, vma,
> + copy_user_huge_page(new_page, old_page, address, vma,
> pages_per_huge_page(h));
> __SetPageUptodate(new_page);
> set_page_huge_active(new_page);
> @@ -3817,7 +3818,7 @@ static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
> hugetlb_count_add(pages_per_huge_page(h), mm);
> if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {
> /* Optimization, do the COW without a second fault */
> - ret = hugetlb_cow(mm, vma, haddr, ptep, page, ptl);
> + ret = hugetlb_cow(mm, vma, address, ptep, page, ptl);
> }
>
> spin_unlock(ptl);
> @@ -3971,7 +3972,7 @@ int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
>
> if (flags & FAULT_FLAG_WRITE) {
> if (!huge_pte_write(entry)) {
> - ret = hugetlb_cow(mm, vma, haddr, ptep,
> + ret = hugetlb_cow(mm, vma, address, ptep,
> pagecache_page, ptl);
> goto out_put_page;
> }
>
