Operating Systems When to switch a process e Clock interrupt H process has executed for the maximum allowable time slice e y interrupt G Memory fault memory address is in virtual memory so it must be brought into main memory G Trap H error occurred H may cause process to be moved to exit state 矿 Supervisor call管理程序调用 A such as file open Gao Haichang, Software School, Xidian University 15Operating Systems Gao Haichang , Software School, Xidian University 15 When to Switch a Process  Clock interrupt  process has executed for the maximum allowable time slice  I/O interrupt  Memory fault  memory address is in virtual memory so it must be brought into main memory  Trap  error occurred  may cause process to be moved to Exit state  Supervisor call 管理程序调用  such as file open