70 lines
1.6 KiB
C
70 lines
1.6 KiB
C
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/*
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* Generic cache management functions. Everything is arch-specific,
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* but this header exists to make sure the defines/functions can be
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* used in a generic way.
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*
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* 2000-11-13 Arjan van de Ven <arjan@fenrus.demon.nl>
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*
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*/
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#ifndef _LINUX_PREFETCH_H
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#define _LINUX_PREFETCH_H
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#include <linux/types.h>
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#include <asm/processor.h>
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#include <asm/cache.h>
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/*
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prefetch(x) attempts to pre-emptively get the memory pointed to
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by address "x" into the CPU L1 cache.
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prefetch(x) should not cause any kind of exception, prefetch(0) is
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specifically ok.
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prefetch() should be defined by the architecture, if not, the
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#define below provides a no-op define.
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There are 3 prefetch() macros:
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prefetch(x) - prefetches the cacheline at "x" for read
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prefetchw(x) - prefetches the cacheline at "x" for write
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spin_lock_prefetch(x) - prefectches the spinlock *x for taking
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there is also PREFETCH_STRIDE which is the architecure-prefered
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"lookahead" size for prefetching streamed operations.
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*/
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/*
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* These cannot be do{}while(0) macros. See the mental gymnastics in
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* the loop macro.
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*/
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#ifndef ARCH_HAS_PREFETCH
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static inline void prefetch(const void *x) {;}
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#endif
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#ifndef ARCH_HAS_PREFETCHW
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static inline void prefetchw(const void *x) {;}
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#endif
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#ifndef ARCH_HAS_SPINLOCK_PREFETCH
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#define spin_lock_prefetch(x) prefetchw(x)
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#endif
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#ifndef PREFETCH_STRIDE
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#define PREFETCH_STRIDE (4*L1_CACHE_BYTES)
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#endif
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static inline void prefetch_range(void *addr, size_t len)
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{
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#ifdef ARCH_HAS_PREFETCH
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char *cp;
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char *end = addr + len;
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for (cp = addr; cp < end; cp += PREFETCH_STRIDE)
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prefetch(cp);
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#endif
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}
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#endif
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