Line data Source code
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) - prefetches 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 : #ifndef ARCH_HAS_PREFETCH
38 : #define prefetch(x) __builtin_prefetch(x)
39 : #endif
40 :
41 : #ifndef ARCH_HAS_PREFETCHW
42 : #define prefetchw(x) __builtin_prefetch(x,1)
43 : #endif
44 :
45 : #ifndef ARCH_HAS_SPINLOCK_PREFETCH
46 : #define spin_lock_prefetch(x) prefetchw(x)
47 : #endif
48 :
49 : #ifndef PREFETCH_STRIDE
50 : #define PREFETCH_STRIDE (4*L1_CACHE_BYTES)
51 : #endif
52 :
53 : static inline void prefetch_range(void *addr, size_t len)
54 : {
55 : #ifdef ARCH_HAS_PREFETCH
56 1 : char *cp;
57 : char *end = addr + len;
58 :
59 : for (cp = addr; cp < end; cp += PREFETCH_STRIDE)
60 : prefetch(cp);
61 : #endif
62 : }
63 :
64 : #endif
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