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1 解答题 1）在操作系统中,P操作和V操作各自的动作是如何定义的? 2）一般说来,文件系统应具备哪些功能? 3）作业调度和进程调度各自的主要功能是什么? 4）什么是分页?什么是分段?二者主要有何区别? 参考答案 1）答P操作顺序执行下述两个动作: （1）信号量的值减1,即S=S-1; （2）如果 S≥0,则该进程继续执行;如果 S<0,则把该进程的状态置为阻塞态,把相应的PCB连入信号量队列的末尾,并放弃处理机,进行等待（直至其他进程在S上执行V操作,把它释放出来为止）。 V操作顺序执行下述两个动作:
1 answer questions 1) In the operating system, P operation and V operation of the respective actions is how to define? 2) In general, the file system should have what functions? 3) Job scheduling and scheduling are the main function of what? 4) What is the paging? What is the segmentation? The main difference between the two? Answer 1) Answer P operation sequence to perform the following two actions: (1) the value of the signal minus 1, that is S = S-1; (2) If S≥0, the process continues; if S <0, the state of the process is set to a blocked state, the corresponding PCB connected to the end of the semaphore queue, and give up the processor, the wait ( Until other processes perform a V operation on S, releasing it). V operation sequence to perform the following two actions: