Category: MPI

How to compile HPL (LINPACK)

This guide will show you how to compile HPL (Linpack) and provide some tips for selecting the best input values for hpl.dat based on my experiences at the student cluster competitions. This benchmark stresses the computers floating point operation capabilities. Although just calculating FLOPs is not reflective of applications typically run on supercomputers, floating point is still important when precise calculations are required. I assume a version of mpi, c/c++/fotran compilers, blas and whatever libraries you need are installed. There...


How to use MPI without NFS

You can use MPI without NFS or a shared file system! We had a situation where we couldn’t find the NFS server or client packages for arm64 for Ubuntu 16.04. We had OpenMPI version 1.10.2 installed on 2 nodes without NFS. When you use MPI without NFS, you need to ensure that the same version of MPI is installed by every node. Then, you have to ensure that the same data files, which include the program, hostnames file, and input files,...


How to Fix OpenMPI ORTE Error: unknown option “–hnp-topo-sig”

We encountered an ORTE bug with the error message, Error: unknown option “–hnp-topo-sig”, while using OpenMPI version 1.10.2 for arm64 on Ubuntu 14.04 server. More specifically, we ran the following command using 2 nodes with MPI: mpirun –hostfile /nfs/hostnames -n 4 /nfs/mpi-hello-world/mpi_hello_world

ORTE errors can happen because of a variety of different things, but it’s usually because your mpirun is not the same version as your mpi compiler. Even if you think that you only have one MPI version, you may in...


Running MPI – Common MPI Troubleshooting Problems

In this post, I’ll list some common troubleshooting problems that I have experienced with MPI libraries after I compiled MPICH on my cluster for the first time. The following assumes that: You have at least 2 nodes as part of your cluster. You have MPI compiled inside a NFS (Network File System), a shared folder. I will divide the common problems into separate sections. For my first installation of an MPI library, I was using   MPI Paths on each...