Messages in this thread | | | Subject | Re: [RFC PATCH 1/2] mm/hugetlbfs: Attempt PUD_SIZE mapping alignment if PMD sharing enabled | From | Mike Kravetz <> | Date | Thu, 31 Mar 2016 09:45:15 -0700 |
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On 03/30/2016 07:18 PM, Naoya Horiguchi wrote: > On Mon, Mar 28, 2016 at 06:12:49PM -0700, Mike Kravetz wrote: >> When creating a hugetlb mapping, attempt PUD_SIZE alignment if the >> following conditions are met: >> - Address passed to mmap or shmat is NULL >> - The mapping is flaged as shared >> - The mapping is at least PUD_SIZE in length >> If a PUD_SIZE aligned mapping can not be created, then fall back to a >> huge page size mapping. > > It would be kinder if the patch description includes why this change. > Simply "to facilitate pmd sharing" is helpful for someone who read > "git log".
Ok, will do.
> >> >> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> >> --- >> fs/hugetlbfs/inode.c | 29 +++++++++++++++++++++++++++-- >> 1 file changed, 27 insertions(+), 2 deletions(-) >> >> diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c >> index 540ddc9..22b2e38 100644 >> --- a/fs/hugetlbfs/inode.c >> +++ b/fs/hugetlbfs/inode.c >> @@ -175,6 +175,17 @@ hugetlb_get_unmapped_area(struct file *file, unsigned long addr, >> struct vm_area_struct *vma; >> struct hstate *h = hstate_file(file); >> struct vm_unmapped_area_info info; >> + bool pud_size_align = false; >> + unsigned long ret_addr; >> + >> + /* >> + * If PMD sharing is enabled, align to PUD_SIZE to facilitate >> + * sharing. Only attempt alignment if no address was passed in, >> + * flags indicate sharing and size is big enough. >> + */ >> + if (IS_ENABLED(CONFIG_ARCH_WANT_HUGE_PMD_SHARE) && >> + !addr && flags & MAP_SHARED && len >= PUD_SIZE) >> + pud_size_align = true; > > This code will have duplicates in the next patch, so how about checking > this in a separate check routine?
Good suggestion, thanks -- Mike Kravetz
> > Thanks, > Naoya Horiguchi >
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