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 <asm/processor.h> 14 #include <asm/cache.h> 15 16 /* 17 prefetch(x) attempts to pre-emptively get the memory pointed to 18 by address "x" into the CPU L1 cache. 19 prefetch(x) should not cause any kind of exception, prefetch(0) is 20 specifically ok. 21 22 prefetch() should be defined by the architecture, if not, the 23 #define below provides a no-op define. 24 25 There are 3 prefetch() macros: 26 27 prefetch(x) - prefetches the cacheline at "x" for read 28 prefetchw(x) - prefetches the cacheline at "x" for write 29 spin_lock_prefetch(x) - prefectches the spinlock *x for taking 30 31 there is also PREFETCH_STRIDE which is the architecure-prefered 32 "lookahead" size for prefetching streamed operations. 33 34 */ 35 36 /* 37 * These cannot be do{}while(0) macros. See the mental gymnastics in 38 * the loop macro. 39 */ 40 41 #ifndef ARCH_HAS_PREFETCH 42 #define ARCH_HAS_PREFETCH prefetch(const void * x)43static inline void prefetch(const void *x) {;} 44 #endif 45 46 #ifndef ARCH_HAS_PREFETCHW 47 #define ARCH_HAS_PREFETCHW prefetchw(const void * x)48static inline void prefetchw(const void *x) {;} 49 #endif 50 51 #ifndef ARCH_HAS_SPINLOCK_PREFETCH 52 #define ARCH_HAS_SPINLOCK_PREFETCH 53 #define spin_lock_prefetch(x) prefetchw(x) 54 #endif 55 56 #ifndef PREFETCH_STRIDE 57 #define PREFETCH_STRIDE (4*L1_CACHE_BYTES) 58 #endif 59 60 #endif 61