topic Re: CPU utilization is high in Operating System - HP-UX

CPU utilization is high

Inderjit Singh_1 — Wed, 14 May 2003 10:55:55 GMT

I have an L2000 server with hp-ux 11i.Weblogic application is running in that server.I could see a CPU utilization is almost 100% frequently.But there is no memory & disk bottleneck.Is there is any parameter to be tuned from O.S side?

Regards
Karthic

Re: CPU utilization is high

Pete Randall — Wed, 14 May 2003 10:58:48 GMT

There's not really any kernel paramters that can be tuned to increase CPU capacity. You need to look at the application, the load on the system, or at increasing the systems capacity by adding more or faster CPU's.

Pete

Re: CPU utilization is high

Bill McNAMARA_1 — Wed, 14 May 2003 11:03:41 GMT

is you system swapping at the time? run less unnecessary programs and watch program priorities.

ps -ef

Re: CPU utilization is high

Filosofo — Wed, 14 May 2003 12:26:00 GMT

How many time the system is up ?

Filo

Re: CPU utilization is high

Jeff Schussele — Wed, 14 May 2003 12:44:42 GMT

Hi Karthic,

When CPU % is high you need to also check the CPU run queue for entries - so also go to CPU by Proc ("a" in glance) and the global report ("g" in glance). You should be looking at processes in CPU order, so go to the thresholds page ("o" in glance & set CPU as the sort criteria.

If you consistently have multiple processes in the run queue you definitely have the possibility of a CPU bottleneck.

Possible ways to mitigate this are as follows:

1) Use nice to prioritize important procs & conversely to deprioritize unimportant procs.

2) Use rtprio or rtsched on important procs.

3) Run batch jobs during non-peak hours

4) Add another (or faster) processor.

HTH,
Jeff

Re: CPU utilization is high

Steve Steel — Wed, 14 May 2003 13:56:37 GMT

Hi

Which software version do you have

weblogic and java

Steve Steel

Re: CPU utilization is high

John Meissner — Wed, 14 May 2003 14:10:09 GMT

you could use measureware (liscensed product) to determine the cpu utilization over a very long period of time. We use this tool for determining a lot of performance issues with our servers. It really breaks the info down very minutely and lets you see almost any detail of what's going on and when.
take a look:

http://www.software.hp.com/products/performance/perfview.html

Re: CPU utilization is high

Inderjit Singh_1 — Thu, 15 May 2003 07:04:48 GMT

I dont have glance!Anyway!I'll use the trial version!The system is used for 12 hours.We have Java 1.3(SDK&RTE)for hpux11i.I have raised the issue with application vendor.But I want to know whether I could do some tuning from system side.I would like to thank all for the valuable inputs.

Regards
Karthic

Re: CPU utilization is high

Bill Hassell — Thu, 15 May 2003 11:01:24 GMT

If no processes are running, then CPU usage will be virtually zero, so you can safely assume that the usage is related to the applications. Knowing that the usage is 100% is useless until you see which applications are consuming the CPU cycles. The simplest is to run top and look at the first few apps that show up. As mentioned, there is nothing in the kernel to make the computer run faster. Using 100% CPU is not necessarily a bad situation unless the application is broken. The simple commands:

while :
do
:
done

will consume 100% CPU. However, this will timewaster set of commands may not seem to affect other users as HP-UX will task-switch (aka, timeshare) so that each application gets a fair share of the CPU(s). This context switching can occur in less than one second.

If the applications normally consume 100% CPU and there are plans to have several of these programs running at the same time, you'll need additional CPUs installed to handle the load or be prepared to see the apps running slower as more are added to the mix.

Re: CPU utilization is high

Bill Douglass — Thu, 15 May 2003 11:21:23 GMT

As an alternative to glance, you can use sar to view various system stats.

sar -q 5 10

will report the runqueue size and % of time processes were queued waiting fro CPU. It will repeat 10 times are 5 second intervals.

sar -qucw will show you runqueue, CPU utilization, system call and swap stats as a group.

Finally, you can cron the shell scripts sa1 and sa2 to collect and report on usage over time.

See the sar and sa1 man pages for more details.

Re: CPU utilization is high

Dave Wherry — Thu, 15 May 2003 12:53:57 GMT

Tagging onto Bill Hassell's comments, is the application running slow?
Is this one application taking up 100% and causing other applications to run slow?
You also say it is almost 100% frequently. Is that when the application starts and then the load goes down? Is that when a specific task is performed by the application? A large query for instance.
100% is not necessarily a bad thing. If the application is performing well and not affecting other applications. If the 100% is just a spike and not an average. There may not be a problem.