This document discusses job scheduling and scheduling algorithms in operating systems. It covers the goals of scheduling which include mimicking kernel threads' functionality in user space for better performance and avoiding unnecessary user-kernel transitions. The document also discusses scheduling for CPU-bound versus I/O-bound processes, shortest job first scheduling in batch systems, and round robin scheduling with priority classes in interactive systems.

1. Sistem Operasi IKH311
Job Scheduling
1

2. Scheduler Activations
• Goal – mimic functionality of kernel threads
– gain performance of user space threads
• Avoids unnecessary user/kernel transitions
• Kernel assigns virtual processors to each
process
– lets runtime system allocate threads to processors
• Problem:
Fundamental reliance on kernel (lower
layer)
calling procedures in user space (higher
2
layer)

3. Scheduling
Introduction to Scheduling (1)
• Bursts of CPU usage alternate with periods of I/O
wait
– a CPU-bound process
3
– an I/O bound process

4. Introduction to Scheduling (2)
Scheduling Algorithm Goals 4

5. Scheduling in Batch Systems (1)
An example of shortest job first scheduling
5

6. Scheduling in Batch Systems (2)
Three level scheduling 6

7. Scheduling in Interactive Systems
(1)
• Round Robin Scheduling
– list of runnable processes
– list of runnable processes after B uses up its quantum 7

8. Scheduling in Interactive Systems
(2)
A scheduling algorithm with four priority classes
8