I'm afraid that without any further details, it's hard to help. I don't know why Gadget2 would complain about its parameters file. From what you've stated, it could be a problem with the application itself.
Have you talked to the Gadget2 authors? -- Jeff Squyres jsquy...@cisco.com ________________________________________ From: users <users-boun...@lists.open-mpi.org> on behalf of Diego Zuccato via users <users@lists.open-mpi.org> Sent: Wednesday, January 26, 2022 2:06 AM To: users@lists.open-mpi.org Cc: Diego Zuccato Subject: Re: [OMPI users] Gadget2 error 818 when using more than 1 process? Il 26/01/2022 02:10, Jeff Squyres (jsquyres) via users ha scritto: > I'm afraid I don't know anything about Gadget, so I can't comment there. How > exactly does the application fail? Neither did I :( It fails saying a 'timestep' is 0, and that's usually caused by an error in the parameters file. But the parameters file is OK, and it actually works if the user runs it in a single process. Or even with multithreaded runs, sometimes and on some nodes. That's quite random :( But the runs are usually single-node (simple examples for students). > Can you try upgrading to Open MPI v4.1.2? That would be a real mess. I'm stuck with packages provided by Debian stable. I lack both the manpower and the knowledge to compile everything from scratch, given the intricate relations between slurm, openmpi, infiniband, etc. :( > What networking are you using? Infiniband (Mellanox cards, w/ Debian-supplied drivers and support programs) and ethernet. Infiniband is also used by IPoIB to reach the storage servers (gluster). Some nodes lacks IB, so access to the storage is achieved by a couple of iptables rules. > ________________________________________ > From: users <users-boun...@lists.open-mpi.org> on behalf of Diego Zuccato via > users <users@lists.open-mpi.org> > Sent: Tuesday, January 25, 2022 5:43 AM > To: Open MPI Users > Cc: Diego Zuccato > Subject: [OMPI users] Gadget2 error 818 when using more than 1 process? > > Hello all. > > A user of our cluster is experiencing a weird problem that I can't pinpoint. > > He does have a job script that worked well on every node. I's based on > Gadget2. > > Lately, *sometimes*, the same executable with the same parameters file > works, sometimes it fails. On the same node and submitting with the same > command. On some nodes it always fails. But if it gets reduced to > sequential (asking for just one process), it completes correctly (so the > parameters file, common source of Gadget2 error 818, seems innocent). > > The cluster uses SLURM and limits resources using cgroups, if that matters. > > Seems most of the issues started after upgrading from openmpi 3.1.3 to > 4.1.0 in september. > > Maybe related, the nodes started spitting out these warnings (that IIUC > should be harmless... but I'd like to debug & resolve anyway): > -8<-- > Open MPI's OFI driver detected multiple equidistant NICs from the > current process, but had insufficient information to ensure MPI > processes fairly pick a NIC for use. > This may negatively impact performance. A more modern PMIx server is > necessary to resolve this issue. > -8<-- > > Code is run (from the jobfile) with: > srun --mpi=pmix_v4 ./Gadget2 paramfile > (we also tried with a simple mpirun w/ no extra parameters leveraging > SLURM's integration/autodetection -- same result) > > Any hints? > > TIA > > -- > Diego Zuccato > DIFA - Dip. di Fisica e Astronomia > Servizi Informatici > Alma Mater Studiorum - Università di Bologna > V.le Berti-Pichat 6/2 - 40127 Bologna - Italy > tel.: +39 051 20 95786 -- Diego Zuccato DIFA - Dip. di Fisica e Astronomia Servizi Informatici Alma Mater Studiorum - Università di Bologna V.le Berti-Pichat 6/2 - 40127 Bologna - Italy tel.: +39 051 20 95786
