topic Re: 100% CPU Utilization in Operating System - HP-UX

100% CPU Utilization

Alan Pham — Mon, 27 Oct 2003 21:36:32 GMT

Hi all,

I would like to know what "100% CPU Utilization" really means? For example, I have a Blade1000 Dual-CPU 900MHz/8GB RAM running Solaris8. I have only one Dolphin job running, and the "top" command shows that the CPU is 100% used. I thought 1 job could use at most 1 CPU, thus the CPU normalization would be more or less 50% for a Dual-CPU server?

Thanks!
--alan

Re: 100% CPU Utilization

Patrick Wallek — Mon, 27 Oct 2003 21:48:26 GMT

As with anything else in unix, it depends. If your program is designed to be multi-threaded then it is entirely possible that it could use 100% of both CPUs.

Re: 100% CPU Utilization

Rajeev Shukla — Mon, 27 Oct 2003 21:59:50 GMT

When you use top command it shows % CPU utilization for the process and on the left hand column you'll see processor number i.e 0 or 1 which means that particular CPU is 100% being utilized by that process.
And the process to utilize both the CPU should be multi-threaded application

Re: 100% CPU Utilization

Steven E. Protter — Mon, 27 Oct 2003 22:10:47 GMT

100% CPU utilization means that the CPU has something to do with every time slice.

If you write a program to be multi-threaded, it can actually use 100% of many CPU's. Most scripts however don't do that, which explains the second CPU not being used at full capacity.

A lot of this depends on how the OS handles SMP. There are also a lot of background programs handling things like disk i/o and daemons that will use some time slices on CPU's. Thats why when the OS is working you'll never see complete idle on the CPU's.

SEP

Re: 100% CPU Utilization

Brian Markus — Mon, 27 Oct 2003 23:45:05 GMT

I agree with Steven. It also means that you're getting what you paid for. :) I see tons of accounts where people buy several CPU's and one is at 10 - 50 percent and the others are idle. At least you use what you have.

-Brian.