Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * Generic cache management functions. Everything is arch-specific, | |
3 | * but this header exists to make sure the defines/functions can be | |
4 | * used in a generic way. | |
5 | * | |
6 | * 2000-11-13 Arjan van de Ven <arjan@fenrus.demon.nl> | |
7 | * | |
8 | */ | |
9 | ||
10 | #ifndef _LINUX_PREFETCH_H | |
11 | #define _LINUX_PREFETCH_H | |
12 | ||
13 | #include <linux/types.h> | |
14 | #include <asm/processor.h> | |
15 | #include <asm/cache.h> | |
16 | ||
17 | /* | |
18 | prefetch(x) attempts to pre-emptively get the memory pointed to | |
19 | by address "x" into the CPU L1 cache. | |
20 | prefetch(x) should not cause any kind of exception, prefetch(0) is | |
21 | specifically ok. | |
22 | ||
23 | prefetch() should be defined by the architecture, if not, the | |
24 | #define below provides a no-op define. | |
25 | ||
26 | There are 3 prefetch() macros: | |
27 | ||
28 | prefetch(x) - prefetches the cacheline at "x" for read | |
29 | prefetchw(x) - prefetches the cacheline at "x" for write | |
30 | spin_lock_prefetch(x) - prefectches the spinlock *x for taking | |
31 | ||
32 | there is also PREFETCH_STRIDE which is the architecure-prefered | |
33 | "lookahead" size for prefetching streamed operations. | |
34 | ||
35 | */ | |
36 | ||
37 | /* | |
38 | * These cannot be do{}while(0) macros. See the mental gymnastics in | |
39 | * the loop macro. | |
40 | */ | |
41 | ||
42 | #ifndef ARCH_HAS_PREFETCH | |
43 | static inline void prefetch(const void *x) {;} | |
44 | #endif | |
45 | ||
46 | #ifndef ARCH_HAS_PREFETCHW | |
47 | static inline void prefetchw(const void *x) {;} | |
48 | #endif | |
49 | ||
50 | #ifndef ARCH_HAS_SPINLOCK_PREFETCH | |
51 | #define spin_lock_prefetch(x) prefetchw(x) | |
52 | #endif | |
53 | ||
54 | #ifndef PREFETCH_STRIDE | |
55 | #define PREFETCH_STRIDE (4*L1_CACHE_BYTES) | |
56 | #endif | |
57 | ||
58 | static inline void prefetch_range(void *addr, size_t len) | |
59 | { | |
60 | #ifdef ARCH_HAS_PREFETCH | |
61 | char *cp; | |
62 | char *end = addr + len; | |
63 | ||
64 | for (cp = addr; cp < end; cp += PREFETCH_STRIDE) | |
65 | prefetch(cp); | |
66 | #endif | |
67 | } | |
68 | ||
69 | #endif |