Hi, I have trying to run the Intel IMB benchmarks to compare the performance of Infiniband (IB) vs Ethernet. However, I am not seeing any difference in performance even for communication intensive benchmarks, such as alltoallv.
Each one of my machines has one ethernet interface and an infiniband interface. I use the following command to run the alltoallv benchmark: mpirun --mca btl self,openib,sm -hostfile hosts_ib IMB-MPI1 alltoallv The hosts_ib file contains the IP addresses of the infiniband interfaces, but the performance is the same when I deactivate the IB interfaces and use my hosts_eth file which has the IP addresses of the ethernet interfaces. Am I missing something? What is really happening when I specify the openib btl if I am using the ethernet network? Thanks
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