title: How psutil.cpu_percent() function works?
body: <p>I was executing the below two statements in python interpreter.</p>
  
  <pre><code>&gt;&gt;&gt; psutil.cpu_percent(interval=None, percpu=False)
  2.0
  &gt;&gt;&gt; psutil.cpu_percent(interval=None, percpu=True)
  [1.5, 1.6, 3.7, 3.5]
  </code></pre>
  
  <p>when percpu=False it is expected to give system-wide CPU usage. However, when I try to get each CPU usage, its sum doesn't equal system-wide usage.My question is how exactly cpu_percent function works when percpu=True and percpu=False
  is passed? 
  </p>