Messages in this thread | | | Date | Tue, 1 Jul 2014 23:15:40 +0300 | From | "Kirill A. Shutemov" <> | Subject | Re: [PATCH] rmap: fix pgoff calculation to handle hugepage correctly |
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On Tue, Jul 01, 2014 at 02:50:21PM -0400, Naoya Horiguchi wrote: > On Tue, Jul 01, 2014 at 09:07:39PM +0300, Kirill A. Shutemov wrote: > > Why do we need this special case for hugetlb page ->index? Why not use > > PAGE_SIZE units there too? Or I miss something? > > hugetlb pages are never split, so we use larger page cache size for > hugetlbfs file (to avoid large sparse page cache tree.)
For transparent huge page cache I would like to have native support in page cache radix-tree: since huge pages are always naturally aligned we can create a leaf node for it several (RADIX_TREE_MAP_SHIFT - HPAGE_PMD_ORDER) levels up by tree, which would cover all indexes in the range the huge page represents. This approach should fit hugetlb too. And -1 special case for hugetlb. But I'm not sure when I'll get time to play with this...
-- Kirill A. Shutemov
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