https://community.intel.com/t5/Intel-MPI-Library/How-communication-between-ranks-works/m-p/922589#M2402 <P>Ranks within a node can exchange messages directly. &nbsp;Usually, you would have enabled shm (a normal default) so that this is done memcpy style.</P> Wed, 05 Mar 2014 14:54:00 GMT TimP 2014-03-05T14:54:00Z https://community.intel.com/t5/Intel-MPI-Library/How-communication-between-ranks-works/m-p/922588#M2401 <P>Example of hipo cluster :&nbsp;</P> <P>"Node 1" -&gt; 4 cores so [0,4[ rank</P> <P>"Node 2" -&gt; 4 cores so [4,8[ rank</P> <P>So rank = 0 would be first core in Node 1</P> <P>In a situation like Core #5 wants to send a message to Core #6</P> <P>which are both in "Node 2"</P> <P>What happens?</P> <P><SPAN style="font-size: 1em; line-height: 1.5;">I hope Core 5 doesn't sends its message to Rank #0 in "Node 1" that sends it back to Core #6.</SPAN></P> <P>So how does it works?</P> Sat, 22 Feb 2014 18:36:25 GMT https://community.intel.com/t5/Intel-MPI-Library/How-communication-between-ranks-works/m-p/922588#M2401 Carlos_Alexandre_T_ 2014-02-22T18:36:25Z https://community.intel.com/t5/Intel-MPI-Library/How-communication-between-ranks-works/m-p/922589#M2402 <P>Ranks within a node can exchange messages directly. &nbsp;Usually, you would have enabled shm (a normal default) so that this is done memcpy style.</P> Wed, 05 Mar 2014 14:54:00 GMT https://community.intel.com/t5/Intel-MPI-Library/How-communication-between-ranks-works/m-p/922589#M2402 TimP 2014-03-05T14:54:00Z