blob: 52fbf236a90eaa63c7934d8bb2c1f09b3421d028 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
|
#ifndef __ASM_GENERIC_GETORDER_H
#define __ASM_GENERIC_GETORDER_H
#ifndef __ASSEMBLY__
#include <linux/compiler.h>
#include <linux/log2.h>
/**
* 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.
*/
static inline __attribute_const__ int get_order(unsigned long size)
{
if (__builtin_constant_p(size)) {
if (!size)
return BITS_PER_LONG - PAGE_SHIFT;
if (size < (1UL << PAGE_SHIFT))
return 0;
return ilog2((size) - 1) - PAGE_SHIFT + 1;
}
size--;
size >>= PAGE_SHIFT;
#if BITS_PER_LONG == 32
return fls(size);
#else
return fls64(size);
#endif
}
#endif /* __ASSEMBLY__ */
#endif /* __ASM_GENERIC_GETORDER_H */
|
