title: What is the correct definition of interrupt latency in RTOS?
body: <p>I read two different definition for 'interrupt latency' in RTOS.</p>
  
  <ol>
  <li><p>"In computing, interrupt latency is the time that elapses from when an interrupt is generated to when the source of the interrupt is serviced" 
  (source: <a href="https://en.wikipedia.org/wiki/Interrupt_latency" rel="nofollow noreferrer">https://en.wikipedia.org/wiki/Interrupt_latency</a> )</p></li>
  <li><p>"The ability to guarantee a maximum latency between an external interrupt and the start of the interrupt handler."
  (source: <a href="https://stackoverflow.com/questions/22241264/what-makes-a-kernel-os-real-time">What makes a kernel/OS real-time?</a> )</p></li>
  </ol>
  
  <p>Now, my question is what is the correct definition of 'interrupt latency'?</p>
  
  <p>For example:</p>
  
  <p>External Interrupt occurrence time stamp:  <strong>00 hr:00 min:20 seconds</strong><br>
  Time stamp when execution is jumped inside the ISR:  <strong>00 hr:00 min :25 seconds</strong><br>
  Time stamp when execution exits ISR after servicing: <strong>00 hr:00 min :43 seconds</strong>  </p>
  
  <p>Now what is the interrupt latency time? Is it 5 seconds? or 23 seconds?</p>