topic Re: Changing the ulimit value in Operating System - HP-UX

Changing the ulimit value

paabhi — Fri, 26 Mar 2010 09:07:56 GMT

Hi All,

We got a request from apllication team to change the ulimit value for a user.

$ ulimit -a
time(seconds) unlimited
file(blocks) unlimited
data(kbytes) 1048576
stack(kbytes) 131072

The data value has to be changed from 1GB to unlimited.Is this recommended.What will be the impact..

The total memory in server is 8 GB
I believe the ulimit value is related to "maxdsiz".Currently maxdsiz is set to "0x40000000".Please correct me if i am wrong.

If we want to increase data value to 2GB, do we need to increase value of "maxdsiz" also.

Abhilash

Re: Changing the ulimit value

Horia Chirculescu — Fri, 26 Mar 2010 09:21:05 GMT

Hello,

On HP-UX you cannot increase a soft limit above a kernel imposed hard limit. So if you have your kernel parameter maxdsiz or maxdsiz_64bit smaller than the one you impose for your user, this value from the kernel will be imposed.

Horia.

Re: Changing the ulimit value

paabhi — Fri, 26 Mar 2010 09:43:19 GMT

Hello,

Currently the value of "maxdsiz" is set to 1GB.If I am changing that to 2GB will have a reverse effect ??

Re: Changing the ulimit value

Horia Chirculescu — Fri, 26 Mar 2010 10:02:38 GMT

This segment contains data storage for globals, arrays, statics, locals to main(), strings and space allocated through malloc().

maxdsiz affects only the 32-bit processes. So playing arround with this value would have nothing to do with 64 bit processes for which maxdsiz_64bit setting matters. If the process your application team is talking about is 32 bit, then this setting would have the expected behavior.

"reverse effect" ? Not sure what you mean, but it will just let your 32bit processes use more memory for data storage.

Horia.

Re: Changing the ulimit value

Dennis Handly — Fri, 26 Mar 2010 10:04:20 GMT

>I believe the ulimit value is related to maxdsiz. Currently maxdsiz is set to 0x40000000.

Yes.

>If we want to increase data value to 2GB, do we need to increase value of "maxdsiz" also.

Yes, you must increase to 2 Gb. Existing users may have to log off. Not all 32 bit processes can use more than 1 Gb.

>Currently the value of maxdsiz is set to 1GB. If I am changing that to 2GB will have a reverse effect?

That will just allow it to go to 2 Gb for new user logons.

>Horia: if you have your kernel parameter maxdsiz or maxdsiz_64bit smaller than the one you impose for your user, this value from the kernel will be imposed.

Right. And maxdsiz_64bit must be >= than maxdsiz.