change maximum value for maxssiz

[Attilio Gatto]

Hi,

I am running under HP-UX 11.0. When I perform
a sysdef I receive the value of maxssiz = 2048 and the min-max value 0 - 655360. How can I increase the value of maximum value of maxssiz to greater than 2048?

[James R. Ferguson]

Hi:

First, I'd rely on 'kmtune' and not 'sysdef' to report kernel parameter values on 11.x systems.

Aside from that, you can use SAM's kernel configuration menus to examine, receive help, and/or change kernel parameters.

For 11.0, you will find this document useful:

http://docs.hp.com/hpux/onlinedocs/os/KCparams.OverviewAll.html

Regards!

...JRF...

[Jeff Schussele]

Hi Attilio,

Couple of things:

1) If you're running 64 bit, then the param to look at would be maxssiz_64bit.

2) Look over the man pages for maxssiz, maxdsiz & maxtsiz as they're interrelated.

To increase go into SAM -> Kernel Config -> Configurable Parameters change it there & let SAM rebuild the new kernel & reboot.

Rgds,
Jeff

[V. V. Ravi Kumar_1]

hi,

run SAM
then kernel configuration
then configurable parameters
select maxssiz, then Actions, then modify
a reboot is required

regds

[Arockia Jegan]

Hi,

You can increase the value by using sam or kmtune command. It's a static kernel parameter. So it requires reboot.

#kmtune -s maxssiz=
#mk_kernel
#mv /stand/system /stand/system.prev
#mv /stand/vmunix /stand/vmunix.prev
#kmupdate

[PIYUSH D. PATEL]

Hi,

Use SAM or kmtune and mk_kernel as specified by others. Make sure you read the configuration and description for the paramter which you are increasing.

Piyush

[Attilio Gatto]

Hi,
Yes, I did use SAM to recalculate the value for maxssiz and got back the following message:

"The value specified for tunable parameter "maxssiz", "0x40000000", evaluates to "1073741824" which is more than the maximum allowed value of "401604608".

Is it possible to increase the maximum allowed
value for maxssiz?

[PIYUSH D. PATEL]

Hi,

Do you have a particular value to be set or has somebody recommended it.

You can set the value properly to the recomended size seeing the formula for setting the same.

Piyush

[James R. Ferguson]

Hi (again):

I think the real question is why do you feel you need such an incredibly large value? What runtime error (by 'errno', please) are you experiencing?

Remember, 'maxssiz' is the fence for a processes stack. The default values or moderate increases of them are generally sufficient.

Regards!

...JRF...

[Bill Hassell]

I agree with James...do your programs actually use multi-megabyte stacks? The only time I've seen this was from a newbie programmer that wrote a FORTRAN program with 100 megs of data and called a subroutine using call-by-value (the entire 100 megs went onto the stack) rather than call-by-reference (or a pointer in C-talk). The purpose of maxssiz is to prevent a runaway program from using all of memory.

The vast majority (way more than 90%) of programs need a lot less than 8 megs for a stack. You may have a misleading error message.