If I understand correctly the communication parroter is a one-to-all type of communication isn't it (from your server to your clients)? In this case this might be a credit management issue, where the master is running out of ack buffers and the clients can't acknowledge the retrieval of the data.
Let's try to add "--mca btl_openib_flags 9" to the mpirun command (this disable the RMA communication and forces everything to have a pure send/recv semantics). George. On Jun 27, 2013, at 15:01 , Ed Blosch <eblo...@1scom.net> wrote: > It ran a bit longer but still deadlocked. All matching sends are posted > 1:1with posted recvs so it is a delivery issue of some kind. I'm running a > debug compiled version tonight to see what that might turn up. I may try to > rewrite with blocking sends and see if that works. I can also try adding a > barrier (irecvs, barrier, isends, waitall) to make sure sends are not > buffering waiting for recvs to be posted. > > > Sent via the Samsung Galaxy S™ III, an AT&T 4G LTE smartphone > > > > -------- Original message -------- > From: George Bosilca <bosi...@icl.utk.edu> > Date: > To: Open MPI Users <us...@open-mpi.org> > Subject: Re: [OMPI users] Application hangs on mpi_waitall > > > Ed, > > Im not sure but there might be a case where the BTL is getting overwhelmed by > the nob-blocking operations while trying to setup the connection. There is a > simple test for this. Add an MPI_Alltoall with a reasonable size (100k) > before you start posting the non-blocking receives, and let's see if this > solves your issue. > > George. > > > On Jun 26, 2013, at 04:02 , eblo...@1scom.net wrote: > > > An update: I recoded the mpi_waitall as a loop over the requests with > > mpi_test and a 30 second timeout. The timeout happens unpredictably, > > sometimes after 10 minutes of run time, other times after 15 minutes, for > > the exact same case. > > > > After 30 seconds, I print out the status of all outstanding receive > > requests. The message tags that are outstanding have definitely been > > sent, so I am wondering why they are not getting received? > > > > As I said before, everybody posts non-blocking standard receives, then > > non-blocking standard sends, then calls mpi_waitall. Each process is > > typically waiting on 200 to 300 requests. Is deadlock possible via this > > implementation approach under some kind of unusual conditions? > > > > Thanks again, > > > > Ed > > > >> I'm running OpenMPI 1.6.4 and seeing a problem where mpi_waitall never > >> returns. The case runs fine with MVAPICH. The logic associated with the > >> communications has been extensively debugged in the past; we don't think > >> it has errors. Each process posts non-blocking receives, non-blocking > >> sends, and then does waitall on all the outstanding requests. > >> > >> The work is broken down into 960 chunks. If I run with 960 processes (60 > >> nodes of 16 cores each), things seem to work. If I use 160 processes > >> (each process handling 6 chunks of work), then each process is handling 6 > >> times as much communication, and that is the case that hangs with OpenMPI > >> 1.6.4; again, seems to work with MVAPICH. Is there an obvious place to > >> start, diagnostically? We're using the openib btl. > >> > >> Thanks, > >> > >> Ed > >> _______________________________________________ > >> users mailing list > >> us...@open-mpi.org > >> http://www.open-mpi.org/mailman/listinfo.cgi/users > > > > > > _______________________________________________ > > users mailing list > > us...@open-mpi.org > > http://www.open-mpi.org/mailman/listinfo.cgi/users > > > _______________________________________________ > users mailing list > us...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/users > _______________________________________________ > users mailing list > us...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/users
