diff options
| -rw-r--r-- | include/asm-generic/getorder.h | 23 |
1 files changed, 22 insertions, 1 deletions
diff --git a/include/asm-generic/getorder.h b/include/asm-generic/getorder.h index 67e7245dc9b3..76e9687a3c86 100644 --- a/include/asm-generic/getorder.h +++ b/include/asm-generic/getorder.h @@ -5,7 +5,28 @@ #include <linux/compiler.h> -/* Pure 2^n version of get_order */ +/** + * get_order - Determine the allocation order of a memory size + * @size: The size for which to get the order + * + * Determine the allocation order of a particular sized block of memory. This + * is on a logarithmic scale, where: + * + * 0 -> 2^0 * PAGE_SIZE and below + * 1 -> 2^1 * PAGE_SIZE to 2^0 * PAGE_SIZE + 1 + * 2 -> 2^2 * PAGE_SIZE to 2^1 * PAGE_SIZE + 1 + * 3 -> 2^3 * PAGE_SIZE to 2^2 * PAGE_SIZE + 1 + * 4 -> 2^4 * PAGE_SIZE to 2^3 * PAGE_SIZE + 1 + * ... + * + * The order returned is used to find the smallest allocation granule required + * to hold an object of the specified size. + * + * The result is undefined if the size is 0. + * + * This function may be used to initialise variables with compile time + * evaluations of constants. + */ static inline __attribute_const__ int get_order(unsigned long size) { int order; |