chap2.12.3处理器、中断技术、进程及其实现.2013.ppt

* * Processor State Information Contents of processor registers User-visible registers Control and status registers Stack pointers Program status word (PSW) contains status information Example: the EFLAGS register on Pentium machines Pentium II EFLAGS Register Process Context (进程上下文) User-level context: include process program, process data, user stack Register context: include PSW, stack pointer, general-purpose register System-level context: include PCB, memory region table, kernel stack Process States Process Description Process Control Modes of Execution Process Creation Process Switching Execution of the OS Summary Examples: Process 4. 进程控制和管理 Modes of Execution User mode Less-privileged mode User programs typically execute in this mode System mode, control mode, or kernel mode More-privileged mode Kernel of the operating system 4.进程的控制和管理 Process States Process Description Process Control Modes of Execution Process Creation Process Switching Execution of the OS Summary Examples: Process Process Creation Assign a unique process identifier Allocate space for the process Initialize process control block Set up appropriate linkages Ex: add new process to linked list used for scheduling queue Create of expand other data structures Ex: maintain an accounting file 4.进程的控制和管理 Process Creation login shell scheduler Swap process OS process Get_tty1 login shell Get_ttyn Application Application Application Application Application Process Cancel Find the PCB in the queue by process identifier De-allocate all resources from the process Cancel sub processes of this process Return the process control block to PCB pool Process Description and Control Process States Process Description Process Control Process Creation Process Switching Execution of the OS Summary Examples: Process 4.进程的控制和管理 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 int