Messages in this thread Patch in this message | | | From | zhigang lu <> | Date | Thu, 29 Aug 2019 19:37:22 +0800 | Subject | [PATCH] mm/hugetlb: avoid looping to the same hugepage if !pages and !vmas |
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From: Zhigang Lu <tonnylu@tencent.com>
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 <tonnylu@tencent.com> Reviewed-by: Haozhong Zhang <hzhongzhang@tencent.com> Reviewed-by: Zongming Zhang <knightzhang@tencent.com> --- 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
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