On 6/27/07, Maureen O Flynn <maureen.oflynn@ucd.ie> wrote:
Is this correct?  I am not sure it works as my performance figures
dont indicate any change so perhaps they are not being resized at
all.  Any suggestions regarding how to do this would be great.

To be sure if it works or not, use some really network intensive MPI job such as GMX Alltoall http://www.gromacs.org/component/option,com_docman/task,doc_download/gid,67/

Its a ping pong test which sends msgs of different sizes to all nodes in the cluster and generates some high traffic.. varying the packet sizes and testing would help check if the buffer size is really affected. may be you ran a processor intensive task, and that might be the reason why you didnt find much difference. Or may be check if in the program that you run, the push bit(PSH) is enabled.. In that case even if you make your buffer large, every packet would be sent off immediately, and you cant see the effect..


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N. Rajagopal,
Visit me at http://users.kaski-net.net/~raj/