Methods to improve CPU utilization
Consider a demand-paging system will follow the time - measured utilization:
CPU utilization 20%
Paging disk 97.7%
Other I/O devices 5%
For each of the following, can you tell me whether it will improve CPU utilization?
Install a fast CPU
Install a fast CPU: No
Install a bigger paging disk
Increase the degree of multiprogramming
Decrease the degree of multiprogramming
Install more main memory
Install a faster hard disk, or multiple controllers with multiple hard disk
Add prepaging to the page fetch algorithms
Increase the page size
Install a bigger paging disk: No
(But I'm not sure what's meant by 97.7% paging disk utilization. If the system runs out of pagefile space, it'll stop allocating memory, which would cause apps to shut down.)
Increase the degree of multiprogramming: Does this mean multithreading? If so, increasing the multithreading of an application could help if most of the utilization comes from that single application.
Decrease the degree of multiprogramming: No
Install more main memory: Yes, this is your best bet.
Install a faster hard disk, or multiple controllers with multiple hard disk: Yes, but installing more memory is a better idea.
Add prepaging to the page fetch algorithms: Perhaps marginally.
Increase the page size: No
This was first published in March 2002