From 7049e6800f40046c384c522a990669024d5f5836 Mon Sep 17 00:00:00 2001 From: "David S. Miller" Date: Tue, 21 Jun 2005 16:20:28 -0700 Subject: [PATCH] [SPARC64]: Add prefetch support. The implementation is optimal for UltraSPARC-III and later. It will work, however suboptimally, on UltraSPARC-II and be treated as a NOP on UltraSPARC-I. It is not worth code patching this thing as the highest cost is the code space, and code patching cannot eliminate that. Signed-off-by: David S. Miller --- include/asm-sparc64/processor.h | 34 +++++++++++++++++++++++++++++++++ 1 file changed, 34 insertions(+) diff --git a/include/asm-sparc64/processor.h b/include/asm-sparc64/processor.h index bc1445b904e..d0bee241356 100644 --- a/include/asm-sparc64/processor.h +++ b/include/asm-sparc64/processor.h @@ -192,6 +192,40 @@ extern unsigned long get_wchan(struct task_struct *task); #define cpu_relax() barrier() +/* Prefetch support. This is tuned for UltraSPARC-III and later. + * UltraSPARC-I will treat these as nops, and UltraSPARC-II has + * a shallower prefetch queue than later chips. + */ +#define ARCH_HAS_PREFETCH +#define ARCH_HAS_PREFETCHW +#define ARCH_HAS_SPINLOCK_PREFETCH + +static inline void prefetch(const void *x) +{ + /* We do not use the read prefetch mnemonic because that + * prefetches into the prefetch-cache which only is accessible + * by floating point operations in UltraSPARC-III and later. + * By contrast, "#one_write" prefetches into the L2 cache + * in shared state. + */ + __asm__ __volatile__("prefetch [%0], #one_write" + : /* no outputs */ + : "r" (x)); +} + +static inline void prefetchw(const void *x) +{ + /* The most optimal prefetch to use for writes is + * "#n_writes". This brings the cacheline into the + * L2 cache in "owned" state. + */ + __asm__ __volatile__("prefetch [%0], #n_writes" + : /* no outputs */ + : "r" (x)); +} + +#define spin_lock_prefetch(x) prefetchw(x) + #endif /* !(__ASSEMBLY__) */ #endif /* !(__ASM_SPARC64_PROCESSOR_H) */ -- 2.20.1