diff options
| author | Kirill A. Shutemov <[email protected]> | 2015-11-06 16:30:00 -0800 |
|---|---|---|
| committer | Linus Torvalds <[email protected]> | 2015-11-06 17:50:42 -0800 |
| commit | 1965c8b7ac7dd147663faf77a66a693ac3ddcb85 (patch) | |
| tree | 9f26e091a39be20625434a98e54b2fe395fc6498 | |
| parent | d00181b96eb86c914cb327d1de974a1b71366e1b (diff) | |
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 <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Reviewed-by: Andrea Arcangeli <[email protected]>
Cc: "Paul E. McKenney" <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Aneesh Kumar K.V <[email protected]>
Cc: Christoph Lameter <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Cc: Sergey Senozhatsky <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
| -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 bb91658c603f..f8d1492a114f 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 |