topic Re: max use unshared memory for a process in Operating System - HP-UX

max use unshared memory for a process

Franky Leeuwerck — Tue, 20 Aug 2002 09:19:29 GMT

How can I detect how much unshared memory can be used at most by 1 process ?

This will definitely be equal to the memory size minus the shared memory, but I would like to know if there are other limits.

HP-UX 11

Thanks in advance

Franky Leeuwerck

Re: max use unshared memory for a process

harry d brown jr — Tue, 20 Aug 2002 09:35:29 GMT

buffer cache:

dbc_max_pct
dbc_min_pct

And about forty other kernel parameters that consume memory.

When in doubt add more memory and use the new memory for your process.

live free or die
harry

Re: max use unshared memory for a process

harry d brown jr — Tue, 20 Aug 2002 09:47:29 GMT

Try this document:

http://www.faqs.org/faqs/hp/hpux-faq/section-140.html

or this:

http://www.interex.org/conference/iworks2001/proceedings/1034/1034.pdf

live free or die
harry

Re: max use unshared memory for a process

Mike Stroyan — Wed, 21 Aug 2002 15:07:02 GMT

There are many different limits on memory use, so it is complicated to find out which limit a process will reach first. Here is a list-
- All processes are limited by the available swap, which can be checked with "swapinfo -t" or pstat_getswap(). The value will change as other programs use more or less swap. You can cheat a little on swap allocation by using "chatr +z", but you risk an unexpected exit.
- All processes are limited by the ulimit values that you can check with the shell ulimit commands or getrlimit().
- Processes are limited by the kernel maxdsiz or maxdsize_64bit parameters.
- 32-bit processes are limited by the address space. Processes linked with '-N' start mallocing at the top of the text and data areas. Processes linked without '-N' start mallocing around 0x40000000. Their malloc calls are then stopped at 0x80000000 unless the ld/chatr +q3p feature is used to allow them to grow to almost 0xc0000000. The 11i release also has a +q4p feature that allows malloc to reach almost 0xf0000000.

I have attached a couple of programs that report some memory features affecting maximum data size.