Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
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
43static inline void prefetch(const void *x) {;}
44#endif
45
46#ifndef ARCH_HAS_PREFETCHW
47static 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
58static 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