Context Switching Group 1 – Presented by David Calhoun Question 3.7: What are the actions taken by the kernel to context-switch between processes?
Multitasking (real life) (Look carefully...)
Multitasking (OS) (process scheduler)
What is a context switch? -process of suspending and resuming processes -triggered by interrupt (for instance, an IO interrupt), preemptive multitasking, or as part of user/kernel mode switching -process context represented by the Process Control Block (PCB)
Process Control Block (PCB) The PCB is "the manifestation of a process in an operating system" Harvey M. Deitel (1984) . An introduction to operating systems
What's in the PCB?
-PCB implementations differ, but generally contain:
Process ID (PID)
Process state (fig 3.2) (ready, running, waiting, etc)
Registers (including Program Counter)
Memory management info (address space of the process)