title: MPI: cores or processors?
body: <p>Hi I am kind of MPI noob so please bear with me on this one. :) </p>
  
  <p>Say I have an MPI program called foo.c and I run the executable with </p>
  
  <p>mpirun -np 3 ./foo</p>
  
  <p>Now this means the program will be run in parallel using 3 processors (1 <em>process</em> per processor). But since most processors today have more than one core, (take 2 cores per processor say) does this mean the program will be run on 3 cores or 3 processors? </p>
  
  <p>Probably this has to do with my poor understanding of what the difference between a core and a processor really is so if you could also explain a little more that would be helpful.</p>
  
  <p>Thank you.</p>