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Changing the ulimit value

paabhi
Frequent Advisor

Changing the ulimit value

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
4 REPLIES
Horia Chirculescu
Honored Contributor

Re: Changing the ulimit value

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.
Best regards from Romania,
Horia.
paabhi
Frequent Advisor

Re: Changing the ulimit value

Hello,

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

Re: Changing the ulimit value

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.
Best regards from Romania,
Horia.
Dennis Handly
Acclaimed Contributor

Re: Changing the ulimit value

>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.