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Subject: Re: [OMPI users] [openib] segfault when using openib btl
From: Eloi Gaudry (eg_at_[hidden])
Date: 2010-07-15 04:08:13


hi Rolf,

unfortunately, i couldn't get rid of that annoying segmentation fault when selecting another bcast algorithm.
i'm now going to replace MPI_Bcast with a naive implementation (using MPI_Send and MPI_Recv) and see if that helps.

regards,
éloi

On Wednesday 14 July 2010 10:59:53 Eloi Gaudry wrote:
> Hi Rolf,
>
> thanks for your input. You're right, I miss the
> coll_tuned_use_dynamic_rules option.
>
> I'll check if I the segmentation fault disappears when using the basic
> bcast linear algorithm using the proper command line you provided.
>
> Regards,
> Eloi
>
> On Tuesday 13 July 2010 20:39:59 Rolf vandeVaart wrote:
> > Hi Eloi:
> > To select the different bcast algorithms, you need to add an extra mca
> > parameter that tells the library to use dynamic selection.
> > --mca coll_tuned_use_dynamic_rules 1
> >
> > One way to make sure you are typing this in correctly is to use it with
> > ompi_info. Do the following:
> > ompi_info -mca coll_tuned_use_dynamic_rules 1 --param coll
> >
> > You should see lots of output with all the different algorithms that can
> > be selected for the various collectives.
> > Therefore, you need this:
> >
> > --mca coll_tuned_use_dynamic_rules 1 --mca coll_tuned_bcast_algorithm 1
> >
> > Rolf
> >
> > On 07/13/10 11:28, Eloi Gaudry wrote:
> > > Hi,
> > >
> > > I've found that "--mca coll_tuned_bcast_algorithm 1" allowed to switch
> > > to the basic linear algorithm. Anyway whatever the algorithm used, the
> > > segmentation fault remains.
> > >
> > > Does anyone could give some advice on ways to diagnose the issue I'm
> > > facing ?
> > >
> > > Regards,
> > > Eloi
> > >
> > > On Monday 12 July 2010 10:53:58 Eloi Gaudry wrote:
> > >> Hi,
> > >>
> > >> I'm focusing on the MPI_Bcast routine that seems to randomly segfault
> > >> when using the openib btl. I'd like to know if there is any way to
> > >> make OpenMPI switch to a different algorithm than the default one
> > >> being selected for MPI_Bcast.
> > >>
> > >> Thanks for your help,
> > >> Eloi
> > >>
> > >> On Friday 02 July 2010 11:06:52 Eloi Gaudry wrote:
> > >>> Hi,
> > >>>
> > >>> I'm observing a random segmentation fault during an internode
> > >>> parallel computation involving the openib btl and OpenMPI-1.4.2 (the
> > >>> same issue can be observed with OpenMPI-1.3.3).
> > >>>
> > >>> mpirun (Open MPI) 1.4.2
> > >>> Report bugs to http://www.open-mpi.org/community/help/
> > >>> [pbn08:02624] *** Process received signal ***
> > >>> [pbn08:02624] Signal: Segmentation fault (11)
> > >>> [pbn08:02624] Signal code: Address not mapped (1)
> > >>> [pbn08:02624] Failing at address: (nil)
> > >>> [pbn08:02624] [ 0] /lib64/libpthread.so.0 [0x349540e4c0]
> > >>> [pbn08:02624] *** End of error message ***
> > >>> sh: line 1: 2624 Segmentation fault
> > >>>
> > >>> \/share\/hpc3\/actran_suite\/Actran_11\.0\.rc2\.41872\/RedHatEL\-5\/x
> > >>> 86 _6 4\ /bin\/actranpy_mp
> > >>> '--apl=/share/hpc3/actran_suite/Actran_11.0.rc2.41872/RedHatEL-5/x86_
> > >>> 64 /A c tran_11.0.rc2.41872'
> > >>> '--inputfile=/work/st25652/LSF_130073_0_47696_0/Case1_3Dreal_m4_n2.da
> > >>> t' '--scratch=/scratch/st25652/LSF_130073_0_47696_0/scratch'
> > >>> '--mem=3200' '--threads=1' '--errorlevel=FATAL' '--t_max=0.1'
> > >>> '--parallel=domain'
> > >>>
> > >>> If I choose not to use the openib btl (by using --mca btl self,sm,tcp
> > >>> on the command line, for instance), I don't encounter any problem and
> > >>> the parallel computation runs flawlessly.
> > >>>
> > >>> I would like to get some help to be able:
> > >>> - to diagnose the issue I'm facing with the openib btl
> > >>> - understand why this issue is observed only when using the openib
> > >>> btl and not when using self,sm,tcp
> > >>>
> > >>> Any help would be very much appreciated.
> > >>>
> > >>> The outputs of ompi_info and the configure scripts of OpenMPI are
> > >>> enclosed to this email, and some information on the infiniband
> > >>> drivers as well.
> > >>>
> > >>> Here is the command line used when launching a parallel computation
> > >>>
> > >>> using infiniband:
> > >>> path_to_openmpi/bin/mpirun -np $NPROCESS --hostfile host.list
> > >>> --mca
> > >>>
> > >>> btl openib,sm,self,tcp --display-map --verbose --version --mca
> > >>> mpi_warn_on_fork 0 --mca btl_openib_want_fork_support 0 [...]
> > >>>
> > >>> and the command line used if not using infiniband:
> > >>> path_to_openmpi/bin/mpirun -np $NPROCESS --hostfile host.list
> > >>> --mca
> > >>>
> > >>> btl self,sm,tcp --display-map --verbose --version --mca
> > >>> mpi_warn_on_fork 0 --mca btl_openib_want_fork_support 0 [...]
> > >>>
> > >>> Thanks,
> > >>> Eloi
> > >
> > > _______________________________________________
> > > users mailing list
> > > users_at_[hidden]
> > > http://www.open-mpi.org/mailman/listinfo.cgi/users

-- 
Eloi Gaudry
Free Field Technologies
Company Website: http://www.fft.be
Company Phone:   +32 10 487 959