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Subject: [OMPI users] OpenMPI: How many connections?
From: devendra rai (dev641_at_[hidden])
Date: 2012-01-24 17:34:46

Hello All, I am trying to find out how many separate connections are opened by MPI as messages are sent. Basically, I have threaded-MPI calls to a bunch of different MPI processes (who, in turn have threaded MPI calls). The point is, with every thread added, are new ports opened (even if the sender-receiver pairs already have a connection between them)? Is there any way to find out? I went through MPI APIs, and the closest thing I found was related to cartographic information. This is not sufficient, since this only tells me the logical connections (or does it)? Reading Open MPI FAQ, I thought adding "--mca btl self,sm,tcp --mca btl_base_verbose 30 -display-map" to mpirun would help. But I am not getting what I need. Basically, I want to know how many ports each process is accessing (reading as well as writing). Basically, at the heart of it, is the scalability of our application. Well, I think there must be plenty of people who would have dealt with the same question. Opening up sniffers may not be possible for me, since I am expected to run MPI applications on a cluster, where I do not have privileges. Does anyone know where to look? Best Devendra Rai