I am writing some code which is computationally expensive, but highly parallelisable. Once parallelised, I intend to run it on a HPC, however to keep the runtime down to within a week, the problem ...

I am using MPI calls to run a procedure on multiple processes using c++. The first few lines in my Main function look like: int main(int argc, char *argv[]){ int comm_sz; int my_rank; MPI_Init(&a...

In order to leverage the GPUs on a system, I'd like to be able to draw a block diagram and understand the connections represented by "nvidia-smi topo -m" output. Here is an example output: Can...

I am trying to send and recieve string using MPI but results are hopless. Send function: MPI_Send(&result, result.size(), MPI_CHAR, 0, 0, MPI_COMM_WORLD); And the recv function: MPI_Recv(...

Hi I am kind of MPI noob so please bear with me on this one. :) Say I have an MPI program called foo.c and I run the executable with mpirun -np 3 ./foo Now this means the program will be run i...

I am compiling a message passing program using openmpi with mpicxx on a Linux desktop. My makefile does the following: mpicxx -c readinp.cpp mpicxx -o exp_fit driver.cpp readinp.o at which poin...

I am optimising an MPI code and I am working with Gprof. The problem is that the results I obtained are completely unreasonable. My workflow is the following: compiling the code adding -pg as a ...

I'm new to MPI and i would like to send an int array via MPI_Send to another process. // Code example int main(int argc, char ** argv) { int * array; int tag=1; int size; int rank; MPI_Status ...

How to debug mpi program with Clion? Executable is set mpirun, that's why I can not debug as usual, I think, so how to do it? Thanks

How do OpenMPI and MPICH handle security when I send MPI messages between the processes over TCP/IP sockets? In particular, how do they prevent other users of the same network from connecting to a...

I have read the definitions of these terms and my interpretation is that there is a one to one relation between a group and a communicator. A group is a set of processes which wish to communicate w...

I was recently looking at this post about mpirun vs mpiexec and this post about srun vs sbatch, but I am wondering how mpirun relates to slurm and srun. Usually in examples I see, files that get s...

I am using Intel MPI and have encountered some confusing behavior when using mpirun in conjunction with slurm. If I run (in a login node) mpirun -n 2 python -c "from mpi4py import MPI; print(MPI...

The terminology used in the sbatch man page might be a bit confusing. Thus, I want to be sure I am getting the options set right. Suppose I have a task to run on a single node with N threads. Am I ...

I am trying to collect different strings of different length from all processors (including the master node) into a single string (array of characters) at the master node. Here is the prototype for...

Can someone elaborate the differences between the OpenMPI and MPICH implementations of MPI ? Which of the two is a better implementation ?

Say, I run a parallel program using MPI. Execution command mpirun -n 8 -npernode 2 <prg> launches 8 processes in total. That is 2 processes per node and 4 nodes in total. (OpenMPI 1.5). Wh...

I was wondering what are the major differences between openacc and openmp. What about MPI, cuda and opencl ? I understand the differences between openmp and mpi, especially the part about shared a...

For a Lattice Boltzmann simulation of a lid-driven cavity (CFD) I'm decomposing my cubic domain into (also cubic) 8 subdomains, which are computed independently by 8 ranks. Each MPI rank is produci...

In MPI it is possible to run an asynchronous message passing routine (e.g. receive, with MPI_Irecv). Is it possible to attach a callback function to be executed as soon as the request is complete? ...

Given a cluster of several nodes, each of which hosts multiple-core processor, is there any advantage of using MPI between nodes and OpenMP/pthreads within nodes over using pure all-MPI? If I under...

My unix/windows C++ app is already parallelized using MPI: the job is splitted in N cpus and each chunk is executed in parallel, quite efficient, very good speed scaling, the job is done right. Bu...

I have created a docker image based on Ubuntu 16.04 and with all the dependencies needed to run MPI. It is public on docker-hub at: https://hub.docker.com/r/orwel84/ubuntu-16-mpi/ I use this ima...

I have an Python 3 interpreter embedded into an C++ MPI application. This application loads a script and passes it to the interpreter. When I execute the program on 1 process without the MPI launc...

I want to run an MPI job on my Kubernetes cluster. The context is that I'm actually running a modern, nicely containerised app but part of the workload is a legacy MPI job which isn't going to be r...