Hi Ansar, The bandwidth numbers seem a little low. I'd expect something around 7,000 Mbps. To discard issues with MPI, you can try generic benchmarking tools such as those described here> http://linuxaria.com/article/tool-command-line-bandwidth-linux?lang=en If you get similar numbers, you'll have to check your setup. Otherwise, let us know and we'll try to see if there's any performance issue with MPICH. Best, Antonio On 04/15/2014 06:35 AM, Muhammad Ansar Javed wrote:

Hi, I am running benchmarks for MPICH v3.1 performance evaluation on 10G Ethernet connection between two hosts. The performance results are less than expected. Here is complete set of numbers for Latency and Bandwidth tests.

mpj@host3:~/code/benchmarks$ mpiexec -n 2 -f machines ./latency.out Latency: MPICH-C Size ______ Time (us) 1 _________ 37.91 2 _________ 37.76 4 _________ 37.75 8 _________ 39.02 16 ________ 52.71 32 ________ 39.08 64 ________ 37.75 128 _______ 37.77 256 _______ 57.47 512 _______ 37.86 1024 ______ 37.76 2048 ______ 37.88

mpj@host3:~/code/benchmarks$ mpiexec -n 2 -f machines ./bandwidth.out Bandwidth: MPICH-C Size(Bytes) Bandwidth (Mbps) 2048 ______ 412.32 4096 ______ 820.06 8192 ______ 827.77 16384 _____ 1644.36 32768 _____ 2207.52 65536 _____ 4368.76 131072 ____ 2942.93 262144 ____ 4281.17 524288 ____ 4773.78 1048576 ___ 5310.85 2097152 ___ 5382.94 4194304 ___ 5518.97 8388608 ___ 5508.87 16777216 __ 5498.93

My environments consists of two hosts having point-to-point (switch-less) 10Gbps Ethernet connection. Environment (OS, user, directory structure etc) on both hosts is exactly same. There is no NAS or shared file system between hosts. I have attached output of script mpiexec -all.

Are these numbers okay? If not then please suggest performance improvement methodology...

Thanks

-- Regards

Ansar Javed HPC Lab SEECS NUST Contact: +92 334 438 9394 Email: [email protected] <mailto:[email protected]>

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-- Antonio J. Pe�a Postdoctoral Appointee Mathematics and Computer Science Division Argonne National Laboratory 9700 South Cass Avenue, Bldg. 240, Of. 3148 Argonne, IL 60439-4847 [email protected] www.mcs.anl.gov/~apenya