The latency estimate taking 5 hops seems a tad optimistic to me except when i read the English wrong and they mean 1.7 microseconds a hop making it for a 5 hop 5 * 1.7 = 8.5 microseconds in total.
"Not every node is only one hop away, of course. On a fully configured system, you are five hopes away maximum from any socket, so there is some latency. But the delta is pretty small with Dragonfly, with a minimum of about 1.2 microseconds for a short hop, an average of 1.5 microseconds on average, and a maximum of 1.7 microseconds for the five-hop jump, according to Bolding." On Nov 8, 2012, at 7:13 PM, Hearns, John wrote: > Well worth a read: > > > > http://www.theregister.co.uk/2012/11/08/ > cray_cascade_xc30_supercomputer/ > > > > John Hearns | CFD Hardware Specialist | McLaren Racing Limited > McLaren Technology Centre, Chertsey Road, Woking, Surrey GU21 4YH, UK > > > T: +44 (0) 1483 262000 > > D: +44 (0) 1483 262352 > > F: +44 (0) 1483 261928 > E: [email protected] > > W: www.mclaren.com > > > > The contents of this email are confidential and for the exclusive > use of the intended recipient. If you receive this email in error > you should not copy it, retransmit it, use it or disclose its > contents but should return it to the sender immediately and delete > your copy. > > _______________________________________________ > Beowulf mailing list, [email protected] sponsored by Penguin > Computing > To change your subscription (digest mode or unsubscribe) visit > http://www.beowulf.org/mailman/listinfo/beowulf _______________________________________________ Beowulf mailing list, [email protected] sponsored by Penguin Computing To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf
