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Subject: Re: [OMPI users] Problem in Open MPI (v1.8) Performance on 10G Ethernet
From: Ralph Castain (rhc_at_[hidden])
Date: 2014-04-16 06:40:40


I apologize, but I am now confused. Let me see if I can translate:

* you ran the non-MPI version of the NetPipe benchmark and got 9.5Gps on a
10Gps network

* you ran iperf and got 9.61Gps - however, this has nothing to do with MPI.
Just tests your TCP stack

* you tested your bandwidth program on a 1Gps network and got about 90%
efficiency.

Is the above correct? If so, my actual suggestion was to run the MPI
version of NetPipe and to use the OSB benchmark program as well. Your
program might well be okay, but benchmarking is a hard thing to get right
in a parallel world, so you might as well validate it by cross-checking the
result.

I suggest this mostly because your performance numbers are far worse than
anything we've measured using those standard benchmarks, and so we should
first ensure we aren't chasing a ghost.

On Wed, Apr 16, 2014 at 1:41 AM, Muhammad Ansar Javed <
muhammad.ansar_at_[hidden]> wrote:

> Yes, I have tried NetPipe-Java and iperf for bandwidth and configuration
> test. NetPipe Java achieves maximum 9.40 Gbps while iperf achieves maximum
> 9.61 Gbps bandwidth. I have also tested my bandwidth program on 1Gbps
> Ethernet connection and it achieves 901 Mbps bandwidth. I am using the same
> program for 10G network benchmarks. Please find attached source file of
> bandwidth program.
>
> As far as --bind-to core is concerned, I think it is working fine. Here is
> output of --report-bindings switch.
> [host3:07134] MCW rank 0 bound to socket 0[core 0[hwt 0]]: [B/././.]
> [host4:10282] MCW rank 1 bound to socket 0[core 0[hwt 0]]: [B/././.]
>
>
>
>
> On Tue, Apr 15, 2014 at 8:39 PM, Ralph Castain <rhc_at_[hidden]> wrote:
>
>> Have you tried a typical benchmark (e.g., NetPipe or OMB) to ensure the
>> problem isn't in your program? Outside of that, you might want to
>> explicitly tell it to --bind-to core just to be sure it does so - it's
>> supposed to do that by default, but might as well be sure. You can check by
>> adding --report-binding to the cmd line.
>>
>>
>> On Apr 14, 2014, at 11:10 PM, Muhammad Ansar Javed <
>> muhammad.ansar_at_[hidden]> wrote:
>>
>> Hi,
>> I am trying to benchmark Open MPI performance on 10G Ethernet network
>> between two hosts. The performance numbers of benchmarks are less than
>> expected. The maximum bandwidth achieved by OMPI-C is 5678 Mbps and I was
>> expecting around 9000+ Mbps. Moreover latency is also quite higher than
>> expected, ranging from 37 to 59 us. Here is complete set of numbers.
>>
>>
>>
>> *LatencyOpen MPI C Size Time (us)*
>> 1 37.76
>> 2 37.75
>> 4 37.78
>> 8 55.17
>> 16 37.89
>> 32 39.08
>> 64 37.78
>> 128 59.46
>> 256 39.37
>> 512 40.39
>> 1024 47.18
>> 2048 47.84
>>
>>
>>
>>
>> *BandwidthOpen MPI C Size (Bytes) Bandwidth (Mbps)*
>> 2048 412.22
>> 4096 539.59
>> 8192 827.73
>> 16384 1655.35
>> 32768 3274.3
>> 65536 1995.22
>> 131072 3270.84
>> 262144 4316.22
>> 524288 5019.46
>> 1048576 5236.17
>> 2097152 5362.61
>> 4194304 5495.2
>> 8388608 5565.32
>> 16777216 5678.32
>>
>>
>> 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 both hosts. Following are configuration and job launching commands
>> that I am using. Moreover, I have attached output of script ompi_info
>> --all.
>>
>> Configuration commmand: ./configure --enable-mpi-java
>> --prefix=/home/mpj/installed/openmpi_installed CC=/usr/bin/gcc
>> --disable-mpi-fortran
>>
>> Job launching command: mpirun -np 2 -hostfile machines -npernode 1
>> ./latency.out
>>
>> Are these numbers okay? If not then please suggest performance tuning
>> steps...
>>
>> Thanks
>>
>> --
>> Ansar Javed
>> HPC Lab
>> SEECS NUST
>> Contact: +92 334 438 9394
>> Email: muhammad.ansar_at_[hidden]
>> <ompi_info.tar.bz2>_______________________________________________
>> users mailing list
>> users_at_[hidden]
>> http://www.open-mpi.org/mailman/listinfo.cgi/users
>>
>>
>>
>> _______________________________________________
>> users mailing list
>> users_at_[hidden]
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>>
>
>
>
> --
> Regards
>
>
> Ansar Javed
> HPC Lab
> SEECS NUST
> Contact: +92 334 438 9394
> Email: muhammad.ansar_at_[hidden]
>
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