Unix (Solaris?) tools: ps

Here's a C++ program that should demonstrate the influence of allocating memory on some flags used in ps. The program, when run, repeadetly asks for amounts in kilo bytes to be allocated. These chunks can then be observed calling ps. The first thing, however, When the program is run, is that it prints its process id (PID) which then can be used like so:

The meaning of the given flags is:

sz: Virtual memory size in pages (Shown in SZ )
sz: Virtual memory size in kB (Shown in VSZ )
ss: Resident set size in kB (Shown in RSS )
mem: % of rss of physical mem (Shown in %MEM)

// Compile with:
// CC demo_ps_o_vsz.cpp -o demo_ps_o_vsz

#include <unistd.h>
#include <iostream>

int main() {

  unsigned int   kbToAllocate;
  char*          allocatedMemory;

  std::cout << std::endl << "My PID is: " << getpid() << std::endl;

  do {

    std::cout << std::endl << "Allocate Memory [kBytes] (0 ends programm): ";
    std::cin  >>  kbToAllocate;

    allocatedMemory = new char[kbToAllocate * 1024];

    // Different behavior for rss if following block
    // commented out:
    for (unsigned int i=0; i<kbToAllocate; i++) {
      allocatedMemory[i*1024] = 0;
    }

  } while (kbToAllocate);

}


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