System Model o A system consists of a finite number of resources o The resources are partitioned into several types,each consisting of some number of identical(=equivalent) instances. physical resources:CPU cycles,memory space,l/O devices,.. logical resources:files,semaphores,monitors,.. ●System model Resource types R1,R2,...,Rm Each resource type R has Wi instances. Each process may utilize a resource only as follows: request:may wait until it can acquire the resource. ★use release System call examples:request(/release(devices,open()/ close()files,wait(/signal(,.. 口1回年走1,2月Q0 陈香兰(C5,U5TO Operating System OS原理与设i计 March21,20198/45. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . System Model A system consists of a finite number of resources The resources are partitioned into several types, each consisting of some number of identical(=equivalent) instances. ▶ physical resources: CPU cycles, memory space, I/O devices, ... ▶ logical resources: files, semaphores, monitors, ... System model ▶ Resource types R1, R2, . . . , Rm ▶ Each resource type Ri has Wi instances. ▶ Each process may utilize a resource only as follows: ⋆ request: may wait until it can acquire the resource. ⋆ use ⋆ release System call examples: request()/release() devices, open()/ close() files, wait()/signal(), ... 陈香兰 (CS, USTC) Operating System OS原理与设计 March 21, 2019 8 / 45