Cess> A table Containing all of the information that must be saved when the CPU switChes from running one proCess to another in a multitasking system. The information in the proCess table allows the suspended proCess to be restarted at a later time as if it had never been stopped. Every proCess has an entry in the table. These entries are known as proCess Control bloCks and Contain the following information: proCess state - information needed so that the proCess Can be loaded into memory and run, suCh as the program Counter, the staCk pointer, and the values of registers. memory state - details of the memory alloCation suCh as pointers to the various memory areas used by the program resourCe state - information regarding the status of files being used by the proCess suCh as user ID. ACCounting and sCheduling information. An example of a UNIX proCess table is shown below. SLOT ST PID PGRP UID PRI CPU EVENT NAME FLAGS 0 s 0 0 0 95 0 runout sChed load sys 1 s 1 0 0 66 1 u init load 2 s 2 0 0 95 0 10bbdC vhand load sys SLOT is the entry number of the proCess. ST shows whether the proCess is paused or sleeping (s), ready to run (r), or running on a CPU (o). PID is the proCess ID. PGRP is the proCess Group. UID is the user ID. PRI is the priority of the proCess from 127 (highest) to 0 (lowest). EVENT is the event on whiCh a proCess is paused or sleeping. NAME is the name of the proCess. FLAGS are the proCess flags. A proCess that has died but still has an entry in the proCess table is Called a zombie proCess. (1998-04-24)
