ch13 进程.pdf

Objectives CPU shell LINUX LINUX Ctrl-C Ctrl-DCtrl-Z Ctrl-\; ( )bgjobs killlimitnicenohup pspstreesleepsuspendtopulimit 1 13.1 An executing program = a process LINUX LINUX 2 13.2 On a timesharing ()system with only one CPU: Multiple processes are executed simultaneouslyby quickly switching the CPU from one process to another The short CPU time, that is given to a process is called a quantum (100 msec) The technique used by the kernel to choose the next process that gets the CPU is called CPU scheduling cpu CPU scheduling is implemented in the kernel 3 13.3 CPU scheduling on a timesharing system: A priority valueis assigned to every process The process with the highest priority takes the CPU next The simplest scheduling algorithm is called first-come-first-served (FCFS) Another algorithm assigns highest priority to the I/O Bound processes (Processes that spend most of their time doing I/O. Ex: vi editor) Round Robin (RR) A process gets to use the CPU for one quantum and then the CPU is given to another process, the next process in the queue of processes waiting to use the CPU Linux uses a combination of th