topic Re: maxdsiz_64bit in Operating System - HP-UX

maxdsiz_64bit

John Ferro — Sat, 12 Sep 2009 10:12:51 GMT

Hello,

I have server "ia64 hp superdome server SD64B",
I received a request from Application team to increase the size to 48GB as equal to physical memory size. My question how i could know the biggest segment size so according to that i can make my decesion?

Regards,

Re: maxdsiz_64bit

Dennis Handly — Sat, 12 Sep 2009 10:55:41 GMT

You can increase it to 48 Gb or larger, if you have that much swap.

You won't be running very many other applications if this one is going to use all of that space.

Re: maxdsiz_64bit

Hakki Aydin Ucar — Sat, 12 Sep 2009 16:57:27 GMT

Addition to Dennis said about limits it is critical to increase this value ,peruse following:

The reason we limit these values is to ensure that a single process doesn't consume all the available memory. Remember, a process's view of memory is via its Virtual Address Space. A 64-bit process thinks it has access to 16EB of memory. This is the theoretical limit of a 64-bit operating system. HP-UX currently uses only 44 of the 64 bits. This limits the size of the entire address space to only 16TB. This should be enough for the foreseeable future. The fact that HP-UX uses the memory partitioning, known as quadrants, has an effect on how the address space is used.

Re: maxdsiz_64bit

Dennis Handly — Sun, 13 Sep 2009 03:03:18 GMT

>Hakki: HP-UX currently uses only 44 of the 64 bits.

This is most likely a hardware restriction, not software.

>that HP-UX uses the memory partitioning, known as quadrants

This is for PA or Integrity 32 bit. For 64 bit, there are octants and that comes the high order bits.

Re: maxdsiz_64bit

John Ferro — Sun, 13 Sep 2009 08:30:08 GMT

Could you pls. explain what is difference between:

maxssiz
maxtsiz

Regards,

Re: maxdsiz_64bit

Hakki Aydin Ucar — Sun, 13 Sep 2009 08:59:07 GMT

>John:

maxtsiz: the maximum size of a code/text segment

maxdsiz: the maximum size of the user/private data segment

maxssiz: the maximum size of the user stack segment

>Dennis: This is for PA or Integrity 32 bit. For 64 bit, there are octants and that comes the high order bits.

probably you are right, my notes seem little bit older. do you know any document about this topic recent updated ?

Re: maxdsiz_64bit

Dennis Handly — Mon, 14 Sep 2009 02:10:52 GMT

>Hakki: do you know any document about this topic recent updated?

It should be directly related to the Itanium hardware and instruction set.

Re: maxdsiz_64bit

Hein van den Heuvel — Mon, 14 Sep 2009 10:39:38 GMT

http://h20338.www2.hp.com/hpux11i/downloads/aas_white_paper.pdf

Hein.