topic Re: increase ulimit (data) value in Operating System - HP-UX

increase ulimit (data) value

Jonathan Caplette_1 — Wed, 20 May 2009 18:57:56 GMT

Hi guys,

I've a request by Peoplesoft guys working on our servers to increase the data ulimit to higher that 2Gb which is set right now...

# ulimit -a
time(seconds) unlimited
file(blocks) unlimited
data(kbytes) 2097152 <---
stack(kbytes) 131072
memory(kbytes) unlimited
coredump(blocks) 4194303
nofiles(descriptors) 16384

I'm running on Hp-UX 11.11 on a PA-RISC system... I know that's all about maxdsiz and maxsiz_64bit, they are currently set to 2Gb and 4Gb respectively

# kmtune | grep maxd
maxdsiz 0x80000000 - 0X80000000
maxdsiz_64bit 0x100000000 - 0X100000000

How can I increase the maxdsiz to 4Gb? if it is possible...

Regards
Jonathan

Re: increase ulimit (data) value

Steven E. Protter — Wed, 20 May 2009 19:21:12 GMT

Shalom,

Go ahead and use ulimit to raise the data size to unlimited.

kmtune can be used to increase maxdsiz and maxdsiz_64 or use sam kernel.

kmtune -l will tell you whether these parameters are dynamic or a recompile of the kernel and boot is necessary.

SEP

Re: increase ulimit (data) value

Bill Hassell — Wed, 20 May 2009 22:10:52 GMT

You can set maxdsiz to 4GB but the Peoplesoft program (if it is old 32 bit code) must be changed to use the 3rd or 4th quadrant. Normally, a 32 bit program only addresses about 960 MB but can be recompiled to handle up to 1.8GB. The chatr program can change the executable, I would want Peoplesoft support to provide the directions as this code is very expensive. A 32bit program can have local memory up to 3.7GB but there are many, many considerations to making this happen.

Re: increase ulimit (data) value

R.K. # — Thu, 21 May 2009 01:11:55 GMT

Hello Jonathan,

As you see that the maxdsiz is 2 Gb and the size of data (ulimit) is also 2 Gb so i believe you need to increase maxdsiz first.

You can have a look on following links, might help you.

http://docs.hp.com/en/1219/tuningwp.html

http://forums11.itrc.hp.com/service/forums/questionanswer.do?threadId=1329920

Regds,
R.K.

Re: increase ulimit (data) value

Taifur — Thu, 21 May 2009 02:06:47 GMT

Hi
Check below link for ulimit and kmtune
as follows,

http://docs.hp.com/en/B9106-90008/kmtune.1M.html

http://docs.hp.com/en/B2355-90693/ulimit.2.html

Rgds//
Taifur

Re: increase ulimit (data) value

Dennis Handly — Thu, 21 May 2009 06:05:38 GMT

>How can I increase the maxdsiz to 4Gb? if it is possible.

You can increase maxdsiz to 4 Gb with kmtune or SAM. This assumes that Peoplesoft has already done the hard work (that Bill mentions) to be able to use this extra space.

Re: increase ulimit (data) value

Jonathan Caplette_1 — Thu, 21 May 2009 13:09:10 GMT

Thanks all...

I've another question... you all said that I can increase maxdsiz to 4Gb, but it I look in to SAM -> Kernel -> Config.. the Help on maxdsiz says that the maximum value for maxdsiz is 2GB:

Acceptable Values:
maxdsiz for 32-bit processes:

Minimum: 0x40000
Maximum: 0xfffff000 (64-bit kernel), 0x7b03a000 (32-bit kernel)
Default: 0x10000000

Re: increase ulimit (data) value

Don Morris_1 — Thu, 21 May 2009 15:21:45 GMT

0xfffff000 is not 2Gb (that's 4Gb minus one page). If you're on a 32-bit kernel, you can't set it higher -- but neither would setting it higher even possibly do anyone any good [since there's no way a user application would get more than 2Gb on a 32-bit kernel].

Re: increase ulimit (data) value

Jonathan Caplette_1 — Thu, 21 May 2009 16:26:19 GMT

Thanks Don.. you are so right.. I miss interpreted it...

Thanks everyone.. I'll be changing the value...

Re: increase ulimit (data) value

Jonathan Caplette_1 — Thu, 21 May 2009 16:30:47 GMT

closed

Re: increase ulimit (data) value

Dennis Handly — Thu, 21 May 2009 22:33:16 GMT

>Maximum: 0xfffff000

If you are on 11.23 and using ksh you can use:
$ echo $(( 16#fffff000 ))
4294963200

Re: increase ulimit (data) value

Bill Hassell — Thu, 21 May 2009 23:04:53 GMT

> Don: [since there's no way a user application would get more than 2Gb on a 32-bit kernel].

Not quite true. Compile a program for EXEC MAGIC and it will be limited to slightly less than 2 GB. But you can use chatr +q3p enable and you can use up to 2.8 GB, and chatr +q4p enable, you'll get 3.7GB or so. The attached c program will demonstrate that capability -- just follow the comments.