quartz/content/notes/19-cpu-scheduling.md
2022-10-30 13:40:53 +13:00

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---
title: "19-cpu-scheduling"
aliases:
tags:
- cosc204
- lecture
---
why shedule?
- keep cpu busy (cpu utilisation)
- so processed dont hae to spend time waithing for the CPU
- even if cpu is always bust executing processses in different orders can change the average time spent in queue
- cpu burst
- ![](https://i.imgur.com/0eTDVVu.png)
- (diagram is old the timing will have changed)
- between burst - waiting for io
- so that interactive processes respond quickly
- time spent waiting in total
- average time between visits to CPU
- ![](https://i.imgur.com/w9H7MZ7.png)
criteria
- CPU utilisation - % time CPU is busy
- throughput - number of processes completed per time unit
- turnaround time - (for a single process) length of time from submitted to completed
- waiting time - (for a single process) time spent waiting for the CPU
- response time - (for a signle process) average timefrom the submission of a request to a process util the first response in produced
# Scheduling algorithms