CS 3733 Operating Systems
Lecture 2 [1/14/98]: Processes
Reading: Chapter 4.1 and 4.2 of SG and Chapter 2.1 of PUP
What is a process?
Process model:
Process contains program code, stack, space for variables and
a program counter.
Three ways of looking at execution:
- Threads of execution from viewpoint of the processor.
- Execution flow from viewpoint of process.
- Time execution showing which process is active (Gantt chart).
What information must an OS keep about a process?
Context switches and the kernel.
Process states and state diagrams.i
- New: starting up
- Running: instructions being executed
- Waiting: waiting for an event such as I/O
- Ready: waiting to be assigned to a processor
- Halted: finished
SKILL: Understand state diagrams and context switches.
Revision Date: 1/15/98