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 architecture-preferred 32 "lookahead" size for prefetching streamed operations. 33 34 */ 35 36 #ifndef ARCH_HAS_PREFETCH 37 #define prefetch(x) __builtin_prefetch(x) 38 #endif 39 40 #ifndef ARCH_HAS_PREFETCHW 41 #define prefetchw(x) __builtin_prefetch(x,1) 42 #endif 43 44 #ifndef ARCH_HAS_SPINLOCK_PREFETCH 45 #define spin_lock_prefetch(x) prefetchw(x) 46 #endif 47 48 #ifndef PREFETCH_STRIDE 49 #define PREFETCH_STRIDE (4*L1_CACHE_BYTES) 50 #endif 51 52 #endif 53