topic Re: CPU Bottleneck in Operating System - HP-UX

CPU Bottleneck

surya_3 — Sat, 21 Sep 2002 18:30:13 GMT

I have one N-Class server with 4 CPUs 3 CPUs are always idle and 1 CPU is having %CPU more than 96%.

Can any one give some suggestions ...

surya

Re: CPU Bottleneck

MANOJ SRIVASTAVA — Sun, 22 Sep 2002 03:19:44 GMT

Hi

Possibly the application that you are running is a 32 bit one , typically that will not be mutlithreaded and ti will grab one cpu only , so you will find that one of the cpus's will be high where as the others are low , incase you have multithreaded app then you can posibly distribute the load etc.

Manoj Srivastava

Re: CPU Bottleneck

Bill Hassell — Sun, 22 Sep 2002 16:48:10 GMT

If you are only running one program (and it is not multi-threaded) then only one CPU will ever be used. If you run a second or third copy of the program (assuming it makes sense to do so) then the other copies will run in the other CPUs. Without special design in the program (called threading), there is no way to spread out the processing to multiple CPUs.

Re: CPU Bottleneck

Michael Tully — Sun, 22 Sep 2002 22:06:31 GMT

Seems to me you have either a runaway process (a process that has lost it's parent) or a single program that is not very efficient.
My guess is that it is the former, and maybe needs to be killed. If you are unsure what it is paste a copy of your 'top' output. An easy way is to do a 'top -f'

Re: CPU Bottleneck

Timo Ruiter — Mon, 23 Sep 2002 09:55:05 GMT

Hi Surya,

In the output of top you should see the CPU number each process runs on, and, since there are many processes running by default, you should see all CPU-numbers in the output.
If not, something is seriously wrong: one or more CPU's are not functioning...

Regards,
Timo

Re: CPU Bottleneck

Todd Larchuk — Mon, 23 Sep 2002 14:41:44 GMT

You can think about the CPUs as if they were automobiles. If you own 4 automobiles and you need to drive to work, how many automobiles will be busy and how many will be idle? One will be busy and 3 will be idle. If you and your spouse both drive to work, then 2 will be busy and 2 will be idle. If you have children that drive, then you might be able to get up to all 4 busy. You can consider the children as child processes or as threads of the one family process.

In any case, only one person can drive one automobile at a time. It is the same with processes (or kernel level threads) and CPUs.