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Subject: Re: [OMPI users] OpenMPI scaling > 512 cores
From: Scott Shaw (sshaw_at_[hidden])
Date: 2008-06-06 13:13:39

Thank you to all that replied regarding my questions.

I have tried all the options suggested but unfortunately I still run
into the same problem. I am at a point were I have exhausted all of the
options available with the OpenMPI v1.2.2 release and moving to v1.2.6
later today. Hopefully mca_oob_tcp_peer_complete_connect handling is
better and resolves the "connection failed: retrying" messages when
running large core count jobs.


> -----Original Message-----
> From: users-bounces_at_[hidden] [mailto:users-bounces_at_[hidden]]
> Behalf Of Pavel Shamis (Pasha)
> Sent: Wednesday, June 04, 2008 5:18 PM
> To: Open MPI Users
> Subject: Re: [OMPI users] OpenMPI scaling > 512 cores
> Scott Shaw wrote:
> > Hi, I hope this is the right forum for my questions. I am running
> > a problem when scaling >512 cores on a infiniband cluster which has
> > 14,336 cores. I am new to openmpi and trying to figure out the right
> > -mca options to pass to avoid the
> > connection failed:" on a cluster which has infiniband HCAs and OFED
> > v1.3GA release. Other MPI implementation like Intel MPI and mvapich
> > work fine using uDAPL or VERBs IB layers for MPI communications.
> >
> Did you have chance to see this FAQ -
> timeout
> > I find it difficult to understand which network interface or IB
> > being used. When I explicitly state not to use eth0,lo,ib1, or ib1:0
> > interfaces with the cmdline option "-mca oob_tcp_exclude" openmpi
> > continue to probe these interfaces. For all MPI traffic openmpi
> > use IB0 which is the 10.148 network. But with debugging enabled I
> > references trying the 10.149 network which is IB1. Below is the
> > ifconfig network device output for a compute node.
> >
> > Questions:
> >
> > 1. Is there away to determine which network device is being used and
> > have openmpi fallback to another device? With Intel MPI or HP MPI
> > can state not to use a fallback device. I thought "-mca
> > oob_tcp_exclude" would be the correct option to pass but I maybe
> >
> If you want to use the IB verbs , you may specify:
> -mca btl sm.self,openib
> sm - shmem
> self - self comunication
> openib - IB communication (IB verbs)
> > 2. How can I determine infiniband openib device is actually being
> > When running a MPI app I continue to see counters for in/out packets
> > a tcp level increasing when it should be using the IB RDMA device
> > all MPI comms over the IB0 or mtcha0 device? OpenMPI was bundled
> > OFED v1.3 so I am assuming the openib interface should work.
> > ompi_info shows btl_open_* references.
> >
> > /usr/mpi/openmpi-1.2-2/intel/bin/mpiexec -mca
> > btl_openib_warn_default_gid_prefix 0 -mca oob_tcp_exclude
> > eth0,lo,ib1,ib1:0 -mca btl openib,sm,self -machinefile mpd.hosts.$$
> > 1024 ~/bin/test_ompi < input1
> >
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