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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>