Messages in this thread Patch in this message | | | Date | Thu, 8 Mar 2012 13:24:15 -0800 | From | Andrew Morton <> | Subject | Re: linux-next: manual merge of the akpm tree with Linus' tree |
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On Thu, 08 Mar 2012 17:59:02 +0800 Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> wrote:
> Andrew, the patch has been reworked. > > Subject: [PATCH] hugetlb: drop prev_vma in hugetlb_get_unmapped_area_topdown() > > After the call find_vma_prev(mm, addr, &prev_vma), the following condition > is always true: > > !prev_vma || (addr >= prev_vma->vm_end) > > it can happily drop prev_vma and use find_vma() instead of find_vma_prev(). >
Well OK, but the changelog is wrong - we don't call find_vma_prev() here any more.
How does this look?
From: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> Subject: hugetlb: remove prev_vma from hugetlb_get_unmapped_area_topdown()
After looking up the vma which covers or follows the cached search address, the following condition is always true:
!prev_vma || (addr >= prev_vma->vm_end)
so we can stop checking the previous VMA altogether.
Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> ---
arch/x86/mm/hugetlbpage.c | 18 +++++------------- 1 file changed, 5 insertions(+), 13 deletions(-)
diff -puN arch/x86/mm/hugetlbpage.c~hugetlb-drop-prev_vma-in-hugetlb_get_unmapped_area_topdown arch/x86/mm/hugetlbpage.c --- a/arch/x86/mm/hugetlbpage.c~hugetlb-drop-prev_vma-in-hugetlb_get_unmapped_area_topdown +++ a/arch/x86/mm/hugetlbpage.c @@ -308,7 +308,7 @@ static unsigned long hugetlb_get_unmappe { struct hstate *h = hstate_file(file); struct mm_struct *mm = current->mm; - struct vm_area_struct *vma, *prev_vma; + struct vm_area_struct *vma; unsigned long base = mm->mmap_base; unsigned long addr = addr0; unsigned long largest_hole = mm->cached_hole_size; @@ -340,22 +340,14 @@ try_again: if (!vma) return addr; - /* - * new region fits between prev_vma->vm_end and - * vma->vm_start, use it: - */ - prev_vma = vma->vm_prev; - if (addr + len <= vma->vm_start && - (!prev_vma || (addr >= prev_vma->vm_end))) { + if (addr + len <= vma->vm_start) { /* remember the address as a hint for next time */ mm->cached_hole_size = largest_hole; return (mm->free_area_cache = addr); - } else { + } else if (mm->free_area_cache == vma->vm_end) { /* pull free_area_cache down to the first hole */ - if (mm->free_area_cache == vma->vm_end) { - mm->free_area_cache = vma->vm_start; - mm->cached_hole_size = largest_hole; - } + mm->free_area_cache = vma->vm_start; + mm->cached_hole_size = largest_hole; } /* remember the largest hole we saw so far */ _
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