title: MRTG CPU and Memory together
body: <p>So, I have an Adtran router and I'd like to monitor both CPU and memory utilization in a single graph.  Unfortunately Adtran doesn't offer a percentage guage for memory utilization the way it does for CPU utilization.  It does offer two OIDs: one that gives you the free memory in bytes and the other that gives you total memory in bytes.</p>
  
  <p>I would like to create a cpu_memory target in my MRTG configuration that does the necessary math but I can't see a way to do it.  Ideally it would work something like this:</p>
  
  <pre><code># CPU Utilization OID: .1.3.6.1.4.1.664.5.53.1.4.1.0
  # Total Memory OID: .1.3.6.1.4.1.664.5.53.1.4.7.0 (adGenAOSHeapSize)
  # Free Memory OID: .1.3.6.1.4.1.664.5.53.1.4.8.0 (adGenAOSHeapFree)
  
  Target[rtr-cpu_mem]: .1.3.6.1.4.1.664.5.53.1.4.1.0&amp;( 100 - ( .1.3.6.1.4.1.664.5.53.1.4.8.0 / .1.3.6.1.4.1.664.5.53.1.4.7.0 ) ):public@router.local
  # ... rest of config
  </code></pre>
  
  <p>Is this even possible?  Or, will I have to have a separate graph for the memory?</p>