Max available memory per process - how to get it?

[Carl Erhorn]

I have a similar post, but in reply to a different issue, so I will post here too, as it will be more searchable by topic.

I need to learn how to set the maximum data segment memory for a process as high as possible, for my particular hardware setup.

I have a HP D250 (old box!) with 1GB ram, running HPUX 11.0. I have 1.8 GB of swap space on disk. Right now, a simple program that allocates memory in 1MB increments fails at 512MB, with an 'out of memory' error code.

I want to be able to increase this to the maximum that I can with the particular hardware that I have. I have no problem with tuning the kernel and rebuilding it. But I think that the settings I am using should allow something more like 1GB per process, yet I can't reach that.

I've tried linking with -N and -M, checking the ulimit for the user (datasize shows 1GB), tweaking the kernel settings for maxdsiz and maxtsiz, and nothing seems to help. 512MB is where it tops out. swapmem_on is set to 1.

Does anyone have a clue what to do? I've searched around on the web and here on the forums, but haven't located anything yet that helps.

Regards,
--Carl

[Jim Marsden]

Check what your swap is doing at the time you are getting the error with swapinfo -mat and check % total used. If this is high (~90%) then you will need to increase swap (this is because processes reserve swap, even if they don't use it and you will get an out of memory error if processes are unable to reserve swap).

[Wodisch]

Hello Carl,

with your system's amounts of RAM and SWAP you
will not be able to get much more than that anyway...
Even if you set the kernel parameter MAXDSIZ higher
your swap space is much too small.

Sorry,
Wodisch

[John Bolene]

With 1.8 GB of swap and swapmem_on is set to 1, you should be able to get to 1 GB.

What is the settings of maxdsiz?

Also what is setting of maxswapchunks?