操作系统Chapter03_OSProcess Description and Control知识讲稿.pptVIP

* 3.3 Process Description * Processes and Resources * 3.3.1 Operating System Control Structures Information about the current status of each process and resource Tables are constructed for each entity the operating system manages * * Memory Tables Allocation of main memory to processes Allocation of secondary memory to processes Protection attributes for access to shared memory regions Information needed to manage virtual memory * I/O Tables I/O device is available or assigned Status of I/O operation Location in main memory being used as the source or destination of the I/O transfer * File Tables Existence of files Location on secondary memory Current Status Attributes Sometimes this information is maintained by a file management system * 3.3.2 Process Control Block －Process Table Where process is located Attributes in the process control block Program Data Stack * * Process Image * Process Control Block Process identification Identifiers Numeric identifiers that may be stored with the process control block include Identifier of this process Identifier of the process that created this process (parent process) User identifier * Process Control Block Processor State Information User-Visible Registers A user-visible register is one that may be referenced by means of the machine language that the processor executes while in user mode. Typically, there are from 8 to 32 of these registers, although some RISC implementations have over 100. * Process Control Block Processor State Information Control and Status Registers These are a variety of processor registers that are employed to control the operation of the processor. These include Program counter: Contains the address of the next instruction to be fetched Condition codes: Result of the most recent arithmetic or logical operation (e.g., sign, zero, carry, equal, overflow) Status information: Includes interrupt enabled/disabled flags, execution mode * Process Control Block Processor State Information Stack Point