linux-4.4.1/get_order() の履歴(No.1)

• 履歴一覧
• 差分 を表示
• 現在との差分 を表示
• ソース を表示
• linux-4.4.1/get_order() へ行く。
  • 1 (2017-09-19 (火) 10:16:29)

参照元†

• linux-4.4.1/__alloc_from_contiguous()
• linux-4.4.1/__dma_alloc_buffer()
• linux-4.4.1/__dma_alloc_coherent()(arm64)
• linux-4.4.1/dma_alloc_from_coherent()
• linux-4.4.1/dma_free_attrs()(gen)
• linux-4.4.1/snd_malloc_dev_pages()
• linux-4.4.1/snd_malloc_pages()
• linux-4.4.1/vb2_dma_sg_alloc_compacted()

説明†

• パス: [[linux-4.4.1/]]

• FIXME: これは何？
  • 説明

引数†

• unsigned long n

返り値†

• unsigned long

参考†

実装†

/**
 * 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.
 */
#define get_order(n)						\
(								\
	__builtin_constant_p(n) ? (				\
		((n) == 0UL) ? BITS_PER_LONG - PAGE_SHIFT :	\
		(((n) < (1UL << PAGE_SHIFT)) ? 0 :		\
		 ilog2((n) - 1) - PAGE_SHIFT + 1)		\
	) :							\
	__get_order(n)						\

• • linux-4.4.1/ilog2()
  • linux-4.4.1/__get_order()

)

コメント†