title: Setting limit to total physical memory available in Linux
body: <p>I know that I am supposed to set <code>mem=MEMORY_LIMIT</code>. But I do not know where to go, during runtime, or during boot time, in order to set a limit to the total physical memory that the OS has control of.</p>
  
  <p>I am running I/O benchmarks, and I would like to limit the amount of overall physical memory that is available.</p>