1
Context Switching
Group 1 – Presented by David Calhoun
Question 3.7: What are the actions taken by the
kernel to context...
2
Multitasking (real life)
(Look carefully...)
3
Multitasking (OS)
(process scheduler)
4
What is a context switch?
-process of suspending and resuming processes
-triggered by interrupt (for instance, an IO
int...
5
Process Control Block (PCB)
The PCB is "the manifestation of a process in an
operating system"
Harvey M. Deitel (1984) [...
6
What's in the PCB?
7
PCB components
-PCB implementations differ, but generally
contain:
 Process ID (PID)
 Process state (fig 3.2) (ready, ...
8
Overhead
Switching contexts
involves a lot of
overhead (typically a
few milliseconds).
Think of the overhead
involved in...
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水晶礦脈

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不可思議之水晶礦脈

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Transcript of "水晶礦脈"

  1. 1. 1 Context Switching Group 1 – Presented by David Calhoun Question 3.7: What are the actions taken by the kernel to context-switch between processes?
  2. 2. 2 Multitasking (real life) (Look carefully...)
  3. 3. 3 Multitasking (OS) (process scheduler)
  4. 4. 4 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)
  5. 5. 5 Process Control Block (PCB) The PCB is "the manifestation of a process in an operating system" Harvey M. Deitel (1984) [1982]. An introduction to operating systems
  6. 6. 6 What's in the PCB?
  7. 7. 7 PCB components -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) More complete list: p. 104
  8. 8. 8 Overhead Switching contexts involves a lot of overhead (typically a few milliseconds). Think of the overhead involved in multitasking in real life.

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