Re: ��

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Article #22

#22

From: yong
Date: Thu, 22 Dec 2005 10:25

27 lines
2528 bytes

不是文件的副本,是一个文件虚拟成内存后的内存空间首地址

Buzzard wrote:
> 你说的没错啦，但是前面也已经说了，是否”可能“冲突。
> 如果没指定正确的flags参数就要考虑同步。
> 最开始这个帖子我也跟snnn讨论了要指定MAP_PRIVATE
> 那样才会给每个进程一个该映射文件的副本。
> 
> On Wed, 21 Dec 2005 23:55:11 +0800, yong
> <yong.personal.mail@gmail.com> wrote:
> 
> 
>>已经映射为内存空间了就可以避免冲突,mmap在大多数UNIX系统里面都是系统调用,
>>不是用其他库函数组成的,所以不是由程序直接读文件,而是和文件隔了一层系统调
>>用,程序写数据到这块"内存"后,由系统功能将其写入文件,系统已经把读写次序安
>>排好了,man了一下mmap()
>>
>>void * mmap(void *start, size_t length, int prot , int flags, int fd,
>>off_t offset);
>>
>>可以给flags里面送上一个值MAP_SHARED,这样就可以在多个进程中共享这块空间,
>>读写结束后用msync()将缓存内的数据写入文件中.
>>
>>Buzzard wrote:
>>
>>>mmap是内存映射文件，呵呵你说可能冲突吗？
>>>

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From: yong <luoyong_zh@hotmail.com>
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