title: Why the C++ running time I get in profiler is not accurate?
body: <p>I'm trying to profile a C++ application. I've tried gprof, HPCToolkit and ScoreP. My problem is that for different runs I obtain different running times, there's a difference of about 10% from one execution to another (like 2.5 and 2.7 seconds). Why? I remember that when I was using the CrayPat on a cray system there was no difference at all between different executions.
  Thanks</p>
  
  <p>ps: I'm on debian 8</p>