Linux CPU/SYSTEM problem

rkmalik · 04-20-2006, 07:19 AM

Hi,

I have got a linux system, which runs an application. Which meant to utilize all the CPU it can. However, there use to be 0.2% CPU idle. But recently its always 0.0% idle. I noticed on top that SYSTEM% is going high. I think that's what taking 0.2% CPU. This CPU eating application runs as a user.

Now, my question is, is there anyway I can limit a particular user to 80% of CPU. So, that user can never go more than 80% and I will always have some CPU free for SYSTEM.

Thanks in advance!

zulfilee · 04-21-2006, 01:54 AM

See
man ulimit

Cheers
Z

rkmalik · 04-21-2006, 04:34 AM

Doesn't give any clue for limiting CPU usage.

Please help!

zulfilee · 04-21-2006, 06:11 AM

Ok it was CPU time not CPU usage in ulimit.

As for cpu usage you cannot specifically say that a process should use 0% of CPu,etc
You can reduce the priority of process and allow other system processes to use CPU
This can be done with renice command

renice -n 19 pid_of_user_process

If the process is being started then start it with

nice -n 19 process

19 is the lowest priority and -20 the highest.

Cheers
Z

rkmalik · 04-21-2006, 06:14 AM

Is there not anything like QoS for CPU/memory/IO ?

You can do that on Solaris 10. I am sure linux guys must have thought of that.

Emmanuel_uk · 04-21-2006, 06:17 AM

maybe realtime linux kernel is something you want to look into
(saying that I know very very little on the topic, so take it as a shot in the dark)

syg00 · 04-21-2006, 06:20 AM

Of course they have. A project is underway, but is still in development.
Significant patchset against 2.6.17
Yep, you read that right.

Also intersects with cpusets and clustering and various virtual server projects.

Much code that was in kernel space is now in userspace, but the "interested" projects have differing requirements.
Isn't something you can use yet, but will be very handy when polished up.

rkmalik · 04-21-2006, 06:34 AM

Quote:

Originally Posted by syg00

Much code that was in kernel space is now in userspace, but the "interested" projects have differing requirements.
Isn't something you can use yet, but will be very handy when polished up.

That's what is the question. Is there something else I can use. I will have to try that nice "renice" command.