Question

I write app on AIX 5.3 using C++. I want to get current size of process virtual memory. I use getprocs64 function, but with this data I can’t get result as svmon shows.
Please help me.

Thanks.

Answer 1

I have found partially solution that is suitable for me.

I ran small test app and see that pi_dvm, the member of procentry64 structure, will increase if we allocate memory on stack (for example: char arr[1024];) for size of allocated object and some overhead. Noiw, we want to calculate used heap size. We should use mallinfo() function from malloc.h that returns mallinfo struct. We are interested in two fields of mallinfo structure: usmblks and uordblks (about this fields you could read here). Some example code:

pid_t pid = getpid();
struct procentry64 p_info;
if (getprocs64(&p_info, sizeof(p_info), NULL, 0, &pid, 1) < 0) {
  printf("Error!");
}
proc_size = p_info.pi_dvm*getpagesize() + p_info.pi_tsize;
struct mallinfo m = mallinfo();
proc_size += m.usmblks + m.uordblks;
return proc_size; // proc_size in bytes

P.S. I don’t know Why we sum pi_tsize (if anybody knows, please tell us). I get this idea from pg_top sources, but there is a bug, they multiply pi_tsize by 4, but it’s incorrect, because pi_tsize is in bytes.
I hope this solution may help someone 🙂