张惠娟副教授mszhj@163com

张惠娟副教授mszhj@163com内容摘要：

located to a job only if the job is in memory). A job is swapped in and out of memory to the disk. Online munication between the user and the system is provided。 Online system must be available for users to access data and code. 21 PersonalComputer Systems Personal puters – puter system dedicated to a single user. I/O devices – keyboards, mice, display screens, small printers. User convenience and responsiveness. Can adopt technology developed for larger operating system’ often individuals have sole use of puter and do not need advanced CPU utilization of protection features. 22 23 Parallel Systems Tightly coupled system – processors share memory and a clock。 munication usually takes place through the shared memory. Advantages of parallel system: Increased throughput Economical Increased reliability 24 Parallel Systems Symmetric multiprocessing (SMP) Each processor runs an identical copy of the operating system. Many processes can run at once without performance deterioration. Most modern operating systems support SMP  Asymmetric multiprocessing Each processor is assigned a specific task。 master processor schedules and allocates work to slave processors. More mon in extremely large systems 25 Symmetric multiprocessing 26 Distributed Systems Distribute the putation among several physica。