Solution to Critical-Section Problem o A solution to the Critical-Section problem must satisfy: Mutual Exclusion(互斥： If process Pi is executing in its CS,no other processes can be executing in their CSes. ②Progres5(空闲让进)： If no process is executing in its CS and there exist some processes that wish to enter their CSes,the selection of the processes that will enter the CS next cannot be postponed indefinitely Bounded Waiting(有限等待)： A bound must exist on the number of times that other processes are allowed to enter their CSes after a process has made a request to enter its CS and before that request is granted Assume that each process executes at a nonzero speed No assumption concerning relative speed of the N processes 陈话兰xlanchen@ustc.edu:cn http/staff.uO1174O1 Operating System操作系统原理 March29,201913/57. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Solution to Critical-Section Problem A solution to the Critical-Section problem must satisfy: 1 Mutual Exclusion (互斥): If process Pi is executing in its CS, no other processes can be executing in their CSes. 2 Progress (空闲让进): If no process is executing in its CS and there exist some processes that wish to enter their CSes, the selection of the processes that will enter the CS next cannot be postponed indefinitely 3 Bounded Waiting (有限等待): A bound must exist on the number of times that other processes are allowed to enter their CSes after a process has made a request to enter its CS and before that request is granted ⋆ Assume that each process executes at a nonzero speed ⋆ No assumption concerning relative speed of the N processes 陈香兰 xlanchen@ustc.edu.cn http://staff.ustc.edu.cn/~xlanchen (Computer Application Laboratory, CS, USTC @ Hefei Embedded System Laboratory, CS, USTC @ Suzhou) 0117401: Operating System 操作系统原理与设计 March 29, 2019 13 / 57