I have seen a considerable performance boost for my codes by using Jumbo Frames. But are there any systematic tools or strategies to select the optimum MTU size? I have it set as 9000. (Of course, all switiching hardware supports jumbo frames and no talking to the external world required of the interfaces) Have you guys found performance to be MTU sensitive?
Also, are there any switch side parameters that can affect the performance of HPC codes? Specifically I was trying to run VASP which is known to be latency sensitive. I have a 10 Gig E network with a RDMA offload card and am getting average latencies (ping pong) using rping of around 14 microsecs in the MPI tests. Is there a way to figure out what percentage of this latency is in the switch and what %age in the stack, cards and cables? Just trying to figure out which are the battles one picks to fight. Any tips? -- Rahu _______________________________________________ Beowulf mailing list, Beowulf@beowulf.org sponsored by Penguin Computing To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf
