mpi

问题 With the help from Jonathan Dursi and osgx, I've now done the "row decomposition" among the processes: row http://img535.imageshack.us/img535/9118/ghostcells.jpg Now, I'd like to try the "block decomposition" approach (pictured below): block http://img836.imageshack.us/img836/9682/ghostcellsblock.jpg How should one go about it? This time, the MPI_Datatype will be necessary, right? Which datatype would be most appropriate/easy to use? Or can it plausibly be done without a datatype? 回答1: You

问题 I am trying to install an OpenMPI on my Ubuntu (14.04) machine, and I thought that I had succeeded, because I can run codes with mpirun , but recently I have noticed that it's not truly running in parallel. I installed openmpi with the following options: ./configure CXX=g++ CC=gcc F77=gfortran \ F90=gfortran \ FC=gfortran \ --enable-mpi-f77 \ --enable-mpi-f90 \ --prefix=/opt/openmpi-1.6.5 make all sudo make install As I said, I have run a code ( not written by myself ) and it seemed to work

问题 I've looked through many examples and I'm still confused. I've compiled a simple latency check program from here, and it runs perfectly on one host, but when I try to run it on two hosts it hangs. However, running something like hostname runs fine: [hamiltont@4 latency]$ mpirun --report-bindings --hostfile hostfile --rankfile rankfile -np 2 hostname [4:16622] [[5908,0],0] odls:default:fork binding child [[5908,1],0] to slot_list 0 4 [5:12661] [[5908,0],1] odls:default:fork binding child [

问题 I'm not sure that I am correctly understanding what MPI_Scatterv is supposed to do. I have 79 items to scatter amounts a variable amount of nodes. However, when I use the MPI_Scatterv command I get ridiculous numbers (as if the array elements of my receiving buffer are uninitialized). Here is the relevant code snippet: MPI_Init(&argc, &argv); int id, procs; MPI_Comm_rank(MPI_COMM_WORLD, &id); MPI_Comm_size(MPI_COMM_WORLD, &procs); //Assign each file a number and figure out how many files

问题 Closed . This question needs to be more focused. It is not currently accepting answers. Want to improve this question? Update the question so it focuses on one problem only by editing this post. Closed 4 years ago . Can anyone help me get my head around the MPI Groups, Inter and Intra communicators. I have already gone through the MPI documentation(http://www.mpi-forum.org/docs/mpi-2.2/mpi22-report.pdf ) and I couldnt make good sense of these concepts. I would especially appreciate any code

问题 I want to use MPI_Barrier() in my programme, but there are some fatal errors. This is my code: 1 #include <stdio.h> 2 #include "mpi.h" 3 4 int main(int argc, char* argv[]){ 5 int rank, size; 6 7 MPI_Init(&argc, &argv); 8 MPI_Comm_rank(MPI_COMM_WORLD, &rank); 9 MPI_Comm_size(MPI_COMM_WORLD, &size); 10 printf("Hello, world, I am %d of %d. \n", rank, size); 11 MPI_Barrier(MPI_COMM_WORLD); 12 MPI_Finalize(); 13 14 return 0; 15 } And this is the output: Hello, world, I am 0 of 2. Hello, world, I

问题 I want to use MPI_Barrier() in my programme, but there are some fatal errors. This is my code: 1 #include <stdio.h> 2 #include "mpi.h" 3 4 int main(int argc, char* argv[]){ 5 int rank, size; 6 7 MPI_Init(&argc, &argv); 8 MPI_Comm_rank(MPI_COMM_WORLD, &rank); 9 MPI_Comm_size(MPI_COMM_WORLD, &size); 10 printf("Hello, world, I am %d of %d. \n", rank, size); 11 MPI_Barrier(MPI_COMM_WORLD); 12 MPI_Finalize(); 13 14 return 0; 15 } And this is the output: Hello, world, I am 0 of 2. Hello, world, I

问题 I am writing my first program using MPI and I am having hard time trying to properly send data to other processes using MPI_Scatter, modify them and receive the values using MPI_Gather. The code is as follows: int** matrix; int m = 2, n = 2; int status; // could have been int matrix[2][2]; matrix = malloc(m*sizeof(int*)); for(i = 0; i < m; i++) { matrix[i] = malloc(n*sizeof(int)); } matrix[0][0] = 1; matrix[0][1] = 2; matrix[1][0] = 2; matrix[1][1] = 3; MPI_Init( &argc, &argv ); MPI_Comm_rank

问题 I have a c++ solver which I need to run in parallel using the following command: nohup mpirun -np 16 ./my_exec > log.txt & This command will run my_exec independently on the 16 processors available on my node. This used to work perfectly. Last week, the HPC department performed an OS upgrade and now, when launching the same command, I get two warning messages (for each processor). The first one is: -------------------------------------------------------------------------- 2 WARNING: It