MPI runs my program with multiple processes. I'd one of these processes to sleep for a while so that it's using minimal CPU. std::this_thread::sleep_for() looks like what I want, but that thread ...

Can someone explain and tell me more about MPI_Comm_split communicator? MPI_Comm_split(MPI_COMM_WORLD, my_row, my_rank,&my_row_comm); This is just example i met by reading some basic docume...

I need to update some old codes to work with the most recent version of OpenMPI, but I'm very confused by the new --map-by system. In particular, I'm not sure how to replace --cpus-per-proc N. Se...

I am trying to send data from process 0 to process 1. This program succeeds when the buffer size is less than 64kb, but hangs if the buffer gets much larger. The following code should reproduce th...

I downloaded mpj-v0_44 and extracted it to C:\mpj Put Windows system env. variables MPJ_HOME to C:\mpj and in PATH added value C:\mpj\bin I added mpi.jar, mpj.jar in Project Structure -> Librari...

I would like to create a loop over an list of parameters (say 50). The loop should be shared by several processors (say 4) in parallel. I would like each processor to pick the next parameter from...

I would like to display "hello world" via MPI on different Google cloud compute instances with the help of the following code: from mpi4py import MPI size = MPI.COMM_WORLD.Get_size() rank = MPI.C...

I have downloaded an R script from the web that says that it "must be run in an MPI environment". Now I know literally nothing of MPI, except for that it is used for parallel computing, a...

I have the following program C++ program which uses no communication, and the same identical work is done on all cores, I know that this doesn't use parallel processing at all: unsigned n = 1300000...

I have been following the docs for parallel programming in julia and for my mind, which thinks like openMP or MPI, I find the design choice quite strange. I have an application where I want data t...

From here : Is file append atomic in UNIX Consider a case where multiple processes open the same file and append to it. O_APPEND guarantees that seeking to the end of file and then beginning the w...

I'm having a problem with Rmpi wherein I try to load it and I get this error message: > library('Rmpi') Error in dyn.load(file, DLLpath = DLLpath, ...) : unable to load shared library '/usr/li...

Which is the difference and which one should one practically use? I have found this IBM link and this question MPI - one function for MPI_Init and MPI_Init_thread. I am interesting only in C, if th...

I am new to HPC and the task in hand is to do a performance analysis and comparison between MPICH and OpenMPI on a cluster which comprises of IBM servers equipped with dual-core AMD Opteron process...

Consider an MPI application based on two steps which we shall call load and globalReduce. Just for simplicity the software is being described as such yet there is a lot more going on, so it is not ...

How do you send blocks of 2-D array to different processors? Suppose the 2D array size is 400x400 an I want to send blocks of sizes 100X100 to different processors. The idea is that each processor ...

Compiler: gfortran-4.8.5 MPI library: OpenMPI-1.7.2 (preinstalled OpenSuSE 13.2) This program: use mpi implicit none real*16 :: x integer :: ierr, irank, type16 call MPI_Init(ierr) call...

I need to create a communicator with cube topology and then select face of the cube, using the MPI_Cart_Shift implemented messaging between processes that are on the brink. For example I am proce...

The MPI-3 Standard states that MPI_Win_lock(...) with lock type MPI_LOCK_SHARED must be a blocking (exclusive) lock if and only if the origin and target process are the same. MPI_Win_lock_all is th...

I can use MPI_Comm_size to get the number of total processors. But how can I get the number of real physical machine?

I have a small program. #include "mpi.h" #include <stdio.h> int main(int argc, char *argv[]) { int rank, size; int buf; int err; MPI_Status status; err = MPI_Init(&argc, &argv); if...

What is the main difference betweeen the MPI_Allgather and MPI_Alltoall functions in MPI? I mean can some one give me examples where MPI_Allgather will be helpful and MPI_Alltoall will not? and v...

I'm having trouble understanding the MPI_Type_create_struct method. Say we have a struct: struct foo(){ float value; char rank; } And we want to send this struct to another process. Conside ...

I am trying to compile a code with gfortran. One of the first things that happens in the compilation is the creation of constants.mod. Soon after that gfortran tells me: Fatal Error: Cannot read ...

When calling MPI_BCAST, is there any implied synchronization? For example, if the sender process were to get to the MPI_BCAST before others could it do the BCAST and then continue without any ackno...