HP UX kernel parameter

[linux: ps_mon.cfg]

Hi All,
SAP suggest me to change this ux kernel parameter to improve performance of SAP/oracle environment:

maxdsiz_64bit : 2147483647(actual value) to 4294867296(suggest value)

is it right to do this change ? what's happen when I increase this value.


thanks in advance

[Pete Randall]

It makes your kernel a little bigger and uses a few bytes more memory. Unless you're severely constrained on RAM, I see no harm in increasing.


Pete

[Massimo Bianchi]

Hi Fabrizio,
it will only allow a much larger use of the memory for the data region of the program.

There is no harm in changing that value.

Massimo

[Steven E. Protter]

Thats the only thing they suggested you change?

Post kmtune output for some informed advice.

Maybe collect some performance data with the script I'm attaching.

I'm assuming SAP is making this recommendation because of performance issues.

Also, swapinfo -tam

Shows how much you have, how much you are utilizing.

SEP

[Ravi_8]

Hi,

No harm in changing (we do it for many applications).
maxdsiz_64bit is maximun data size for 64 bit appliactions,
at the moment it's 2Gb in ur machine, SAP asking you to increase it to 4Gb

[James R. Ferguson · Accepted solution]

Hi:

'maxdsiz_64bit' controls the limit or ceiling for the maximum data size used for globals, arrays, static variables, local main {}variables, and private memory-mapped files. Since this variable influences the amount of swap reservation required for a process, you may need to increase swapspace too.

As suggested by the '64bit' suffix, this kernel parameter impacts only 64bit processes. 32bit processes are constrained by 'maxdsiz'.

Regards!

...JRF...

[Pete Randall]

From SAM's help on configurable parameters:

maxdsiz and maxdsiz_64bit define the maximum size of the data
storage segment of an executing process for 32-bit and 64-bit
processes, respectively. The data storage segment contains fixed data
storage such as statics and strings, as well as dynamic data space
allocated using sbrk() and malloc().

Increase the value of maxdsiz or maxdsiz_64bit only if you have
one or more processes that use large amounts of data storage space.

Whenever the system loads a process, or an executing process
attempts to expand its data storage segment, the system checks the
size of the process' data storage segment.

If the process' requirements exceed maxdsiz or maxdsiz_64bit,
the system returns an error to the calling process, possibly causing the
process to terminate.


Pete

[Tim D Fulford]

Usually an increase in maxdsix meanas you need to re-vist maxtsiz[_64bit] & maxssiz[_64bit], I usually keep maxdsiz = maxtsiz

[maxtsiz Max text segment size ]
[maxssiz max stack segment size]

Tim

[Caesar_3]

Hello!

I think that you should do this if SAP
says that it needed, because you use SAP.
Your kernel will grow but if it will help
to SAP be more preformance than do it.

Caesar