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-preferred 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 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 65