diff options
| author | Kirill A. Shutemov <kirill.shutemov@linux.intel.com> | 2015-11-07 00:30:00 (GMT) |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2015-11-07 01:50:42 (GMT) |
| commit | 1965c8b7ac7dd147663faf77a66a693ac3ddcb85 (patch) | |
| tree | 9f26e091a39be20625434a98e54b2fe395fc6498 /include | |
| parent | d00181b96eb86c914cb327d1de974a1b71366e1b (diff) | |
| download | linux-1965c8b7ac7dd147663faf77a66a693ac3ddcb85.tar.xz | |
mm: use 'unsigned int' for compound_dtor/compound_order on 64BIT
On 64 bit system we have enough space in struct page to encode
compound_dtor and compound_order with unsigned int.
On x86-64 it leads to slightly smaller code size due usesage of plain
MOV instead of MOVZX (zero-extended move) or similar effect.
allyesconfig:
text data bss dec hex filename
159520446 48146736 72196096 279863278 10ae5fee vmlinux.pre
159520382 48146736 72196096 279863214 10ae5fae vmlinux.post
On other architectures without native support of 16-bit data types the
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/mm_types.h | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index bb91658..f8d1492 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -143,8 +143,19 @@ struct page { unsigned long compound_head; /* If bit zero is set */ /* First tail page only */ +#ifdef CONFIG_64BIT + /* + * On 64 bit system we have enough space in struct page + * to encode compound_dtor and compound_order with + * unsigned int. It can help compiler generate better or + * smaller code on some archtectures. + */ + unsigned int compound_dtor; + unsigned int compound_order; +#else unsigned short int compound_dtor; unsigned short int compound_order; +#endif }; #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && USE_SPLIT_PMD_PTLOCKS |