include/linux/prefetch.h

Source file repositories/reference/linux-study-clean/include/linux/prefetch.h

File Facts

System
Linux kernel
Corpus path
include/linux/prefetch.h
Extension
.h
Size
1591 bytes
Lines
69
Domain
Core OS
Bucket
Core Kernel Interface
Inferred role
Core OS: implementation source
Status
source implementation candidate

Why This File Exists

Core operating-system implementation surface: boot, tasks, memory, VFS, syscall-facing interfaces, synchronization, credentials, and isolation.

Dependency Surface

Detected Declarations

Annotated Snippet

#ifndef _LINUX_PREFETCH_H
#define _LINUX_PREFETCH_H

#include <linux/types.h>
#include <asm/processor.h>
#include <asm/cache.h>

struct page;
/*
	prefetch(x) attempts to pre-emptively get the memory pointed to
	by address "x" into the CPU L1 cache. 
	prefetch(x) should not cause any kind of exception, prefetch(0) is
	specifically ok.

	prefetch() should be defined by the architecture, if not, the 
	#define below provides a no-op define.	
	
	There are 2 prefetch() macros:
	
	prefetch(x)  	- prefetches the cacheline at "x" for read
	prefetchw(x)	- prefetches the cacheline at "x" for write
	
	there is also PREFETCH_STRIDE which is the architecure-preferred 
	"lookahead" size for prefetching streamed operations.
	
*/

#ifndef ARCH_HAS_PREFETCH
#define prefetch(x) __builtin_prefetch(x)
#endif

#ifndef ARCH_HAS_PREFETCHW
#define prefetchw(x) __builtin_prefetch(x,1)
#endif

#ifndef PREFETCH_STRIDE
#define PREFETCH_STRIDE (4*L1_CACHE_BYTES)
#endif

static inline void prefetch_range(void *addr, size_t len)
{
#ifdef ARCH_HAS_PREFETCH
	char *cp;
	char *end = addr + len;

	for (cp = addr; cp < end; cp += PREFETCH_STRIDE)
		prefetch(cp);
#endif
}

static inline void prefetch_page_address(struct page *page)
{
#if defined(WANT_PAGE_VIRTUAL) || defined(HASHED_PAGE_VIRTUAL)
	prefetch(page);
#endif
}

#endif

Annotation

Implementation Notes