Question : linux swap

hi guys, seems to be a problem
i have linux7.3
When i run a pgm (that processes large amt of data), the swap area is not being used.
When i execute free, i can see swap and a lot of memory, but it never gets used.
Usage of swap is being turned on when the system starts in the rc.local file.
There is an entry in the /etc/fstab file as well

I am not able to guess what the problem is
Any help would be appreciated

Answer : linux swap

I thought we were talking about zero swap space used.  That a little is used rules out a whole bunch of problems.

Seeing the numbers just after the program finishes is a lot less useful that seeing them just before it finishes.  You should add to your program something that displays the contents of /proc/meminfo in addition to the /proc/$$/status.  And add the VmRSS line from /proc/$$/status.

But really, I don't see much to look for.  Your program claims to be using about 2.5 GiB of virtual storage, which fits comfortably in your real memory.  It's dying before it has used up the real memory, so that's why swap space is not being used.

Maybe it is simply exceeding its _virtual_ memory allotment.  What does ulimit -a say in the shell from which you invoke your program?

There could be limitations in various places (I don't know) on how much virtual memory a single process can have -- C library, Perl interpreter, kernel.