| 1 |
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| 2 | |
| 3 | * Generic cache management functions. Everything is arch-specific,
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| 4 | * but this header exists to make sure the defines/functions can be
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| 5 | * used in a generic way.
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| 6 | *
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| 7 | * 2000-11-13 Arjan van de Ven <[email protected]>
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| 8 | *
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| 9 |
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| 10 |
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| 11 | #ifndef _LINUX_PREFETCH_H
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| 12 | #define _LINUX_PREFETCH_H
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| 13 |
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| 14 | #include <linux/types.h>
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| 15 | #include <asm/processor.h>
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| 16 | #include <asm/cache.h>
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| 17 |
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| 18 | struct page;
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| 19 | |
| 20 | prefetch(x) attempts to pre-emptively get the memory pointed to
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| 21 | by address "x" into the CPU L1 cache.
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| 22 | prefetch(x) should not cause any kind of exception, prefetch(0) is
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| 23 | specifically ok.
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| 24 |
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| 25 | prefetch() should be defined by the architecture, if not, the
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| 26 | #define below provides a no-op define.
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| 27 |
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| 28 | There are 2 prefetch() macros:
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| 29 |
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| 30 | prefetch(x) - prefetches the cacheline at "x" for read
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| 31 | prefetchw(x) - prefetches the cacheline at "x" for write
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| 32 |
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| 33 | there is also PREFETCH_STRIDE which is the architecure-preferred
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| 34 | "lookahead" size for prefetching streamed operations.
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| 35 |
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| 36 |
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| 37 |
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| 38 | #ifndef ARCH_HAS_PREFETCH
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| 39 | #define prefetch(x) __builtin_prefetch(x)
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| 40 | #endif
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| 41 |
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| 42 | #ifndef ARCH_HAS_PREFETCHW
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| 43 | #define prefetchw(x) __builtin_prefetch(x,1)
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| 44 | #endif
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| 45 |
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| 46 | #ifndef PREFETCH_STRIDE
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| 47 | #define PREFETCH_STRIDE (4*L1_CACHE_BYTES)
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| 48 | #endif
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| 49 |
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| 50 | static inline void prefetch_range(void *addr, size_t len)
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| 51 | {
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| 52 | #ifdef ARCH_HAS_PREFETCH
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| 53 | char *cp;
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| 54 | char *end = addr + len;
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| 55 |
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| 56 | for (cp = addr; cp < end; cp += PREFETCH_STRIDE)
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| 57 | prefetch(cp);
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| 58 | #endif
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| 59 | }
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| 60 |
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| 61 | static inline void prefetch_page_address(struct page *page)
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| 62 | {
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| 63 | #if defined(WANT_PAGE_VIRTUAL) || defined(HASHED_PAGE_VIRTUAL)
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| 64 | prefetch(page);
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| 65 | #endif
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| 66 | }
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| 67 |
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| 68 | #endif
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