From: Zhigang Lu <[email protected]> This change greatly decrease the time of mmaping a file in hugetlbfs. With MAP_POPULATE flag, it takes about 50 milliseconds to mmap a existing 128GB file in hugetlbfs. With this change, it takes less then 1 millisecond.
Signed-off-by: Zhigang Lu <[email protected]> Reviewed-by: Haozhong Zhang <[email protected]> Reviewed-by: Zongming Zhang <[email protected]> --- mm/hugetlb.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 6d7296d..2df941a 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -4391,6 +4391,17 @@ long follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma, break; } } + + if (!pages && !vmas && !pfn_offset && + (vaddr + huge_page_size(h) < vma->vm_end) && + (remainder >= pages_per_huge_page(h))) { + vaddr += huge_page_size(h); + remainder -= pages_per_huge_page(h); + i += pages_per_huge_page(h); + spin_unlock(ptl); + continue; + } + same_page: if (pages) { pages[i] = mem_map_offset(page, pfn_offset); -- 1.8.3.1
