title: How does SGE (Sun Grid Engine) Monitor VMEM (Virtual Memory) Usage for Jobs?
body: <p>SGE enables users to set limits on virtual memory/vmem usage (e.g. the <code>h_vmem</code> argument for a job submission).</p>
  
  <p>But how exactly does SGE monitor VMEM usage and send a kill signal if it is exceeded?  Does it poll at some frequency? Add up some kernel provided value across a process tree? How does this work mechanistically? Even an incomplete explanation or simple pointer to source code would be greatly appreciated.</p>