On 9 Dec 2016, at 9:38 am, Keith Bannister <[email protected]> wrote:

Moreover, that latency should be much smaller if it is using shared memory. If I understand it right, the average throughput = message_size/latency = 6.5 Gbits/sec, which resembles a network throughput to me. I’m sure the memory bus on this machine can sustain much more than that.

Ah, my mistake on this point. Looking at the osu_gather.c code, the correct calculation should be throughput = message_size * nranks / latency = 78 Gbits/sec. So the throughput is OK, but the latency variability is still pretty wild. K _______________________________________________ discuss mailing list [email protected] To manage subscription options or unsubscribe: https://lists.mpich.org/mailman/listinfo/discuss