OPERATING SYSTEMS 1 龚玲 lgong@sjtu.edu.cn
OPERATING SYSTEMS 龚玲 lgong@sjtu.edu.cn 1
Chapter 6:Process Synchronization
Chapter 6: Process Synchronization
REVIEW o Semaphores o http://wenku.baidu.com/course/study/77f1dcccda38376ba flfae94#665ea0c7aa00b52acfc7ca94
REVIEW Semaphores http://wenku.baidu.com/course/study/77f1dcccda38376ba f1fae94#665ea0c7aa00b52acfc7ca94
Goals for today o Classic Problems of Synchronization o Monitors
Goals for today Classic Problems of Synchronization Monitors
Semaphore o Synchronization tool that does not require busy waiting o Semaphore S-integer variable o Two standard operations modify S:acquire0 and release( Originally called PO and VO o Less complicated o Can only be accessed via two indivisible(atomic)operations acquire(){ while value <=0 ;/no-op value--; release(){ value++;
Semaphore Synchronization tool that does not require busy waiting Semaphore S – integer variable Two standard operations modify S: acquire() and release() Originally called P() and V() Less complicated Can only be accessed via two indivisible (atomic) operations