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对信号量，我一直这样认为的，而且初始值为S，当一进程申请资源时，执行wait()操作，mutex--，S值减1；当操作结束后执行signal() 操作，mute++，S值加1。
对于互斥信号量，这就意味着1是unlocked，0是locked
近日看到另外一个说法：
A mutex is a variable that can be in one of two states: unlocked or locked. Consequently, only 1 bit is required to represent it, but in practice an integer often is used, with 0 meaning unlocked and all other values meaning locked. Two procedures are used with mutexes. When a process (or thread) needs access to a critical region, it calls mutex_lock. If the mutex is currently unlocked (meaning that the critical region is available), the call succeeds and the calling thread is free to enter the critical region.
而这就意味着0是unlocked，1是locked
是不是这两者说的不是一个事，我按上面两种方法来实现互斥功能，都成功了，我都糊涂了。
[ 本帖最后由 rock_jq 于 2008-8-7 17:26 编辑 ] |
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发表于 2008-08-07 17:24
