title: "Mem Usage" higher than "VM Size" in WinXP Task Manager
body: <p>In my Windows XP Task Manager, some processes display a higher value in the Mem Usage column than the VMSize. My Firefox instance, for example shows 111544 K as mem usage and 100576 K as VMSize. </p>
  
  <p>According to the help file of Task Manager Mem Usage is the working set of the process and VMSize is the committed memory in the Virtual address space.</p>
  
  <p>My question is, if the number of committed pages for a process is A and the number of pages in physical memory for the same process is B, shouldn't it always  be B ≤ A? Isn't the number of pages in physical memory per process a subset of the committed pages?</p>
  
  <p>Or is this something to do with sharing of memory among processes? Please explain. (Perhaps my definition of 'Working Set' is off the mark).</p>
  
  <p>Thanks.</p>