title: Getting number of cores for EMR cluster
body: <p>I am using 3 instances of r4.2x large for my slave node in my emr cluster which has 8 cpu .How do i determine the number of cores available in the cluster .I used the following command to determine this :</p>
  
  <pre><code>grep cores /proc/cpuinfo
  </code></pre>
  
  <p>It says i have 1 core per cpu .</p>
  
  <p>For spark ETL job is it better to use R series of AWS instance or C series .Also is the above command the right way to determine the cores available for the cluster </p>