Process Description and Control

OS Requirements for Processes

Dispatcher (short-term scheduler)

When does a process gets created?

When does a process gets terminated?

Reasons for Process Termination

Reasons for Process Termination

Process States

Other Useful States

Other Useful States

Process Transitions

Process Transitions

A Five-state Process Model

The need for swapping

New state transitions (mid-term scheduling)

A Seven-state Process Model

Operating System Control Structures

Process Image

Location of the Process Image

Process Identification (in the PCB)

Processor State Information (in PCB)

Process Control Information (in PCB)

Queues as linked lists of PCBs

Process Control Information (in PCB)

Modes of Execution

Process Creation

When to Switch a Process ?

Mode Switching

Steps in Process (Context) Switching

Execution of the Operating System

Nonprocess Kernel (old)

Execution within User Processes

Execution within User Processes

Process-based Operating System