CGS 3763 Operating Systems Concepts Spring 2013 Dan C. Marinescu Office: HEC 304 Office hours: M-Wd 11:30 - 12:30 AM

Lecture 8 – Friday, January 25, 2013 Last time: Process; process state; a process in memory Today: Interrupts Kernel data structures for process management Week in review. Problem solving – chapter 3 Next time Creation and termination of processes Inter-process communication Shared memory Message passing Reading assignments Chapters 3 and 4 of the textbook Chapters 3 and 4 textbook slides 12/28/2018

The state of a process 12/28/2018

Interrupts  provide the means to react to internal and external events 12/28/2018

Interrupt handlers are a component of the kernel 12/28/2018

12/28/2018

12/28/2018

Kernel functions for program execution Process management Scheduling and resource allocation Interrupt handling Error handling 12/28/2018

System calls for process control Load Execute Create, terminate a process Block a process, abort Get process attributes/set process attributes Allocate/deallocate memory for a process 12/28/2018

Control data structure maintained by the kernel To carry out its functions the kernel must maintain information about all objects in the system. For example: Processes  Process Control Block (PCB) Open files  File Control Block (FCB) 12/28/2018

Process Control Block (PCB) The entry for a process contains the following information Process state Program counter CPU registers CPU scheduling information Memory-management information Accounting information I/O status information

Process Control Block (PCB)

CPU Switch From Process to Process

Process Scheduling Queues Job queue – set of all processes in the system Ready queue – set of all processes residing in main memory, ready and waiting to execute Device queues – set of processes waiting for an I/O device Processes migrate among the various queues