openmpi

I have two openmpi programs which I start like this mpirun -n 4 ./prog1 : -n 2 ./prog2 Now how do I use MPI_Comm_size(MPI_COMM_WORLD, &size) such that i get size values as prog1 size=4 prog2 size=2. As of now I get "6" in both programs. This is doable albeit a bit cumbersome to get that. The principle is to split MPI_COMM_WORLD into communicators based on the value of argv[0] , which contains the executable's name. That could be something like that: #include <stdio.h> #include <string.h> #include <stdlib.h> #include <mpi.h> int main( int argc, char *argv[] ) { MPI_Init( &argc, &argv ); int

I am new to MPI. I wrote a simple code to display a matrix using multiple process. Say if I have a matrix of 8x8 and launching the MPI program with 4 processes, the 1st 2 rows will be printed my 1st process the 2nd set of 2 rows will be printed by 2nd thread so on by dividing itself equally. #define S 8 MPI_Status status; int main(int argc, char *argv[]) { int numtasks, taskid; int i, j, k = 0; MPI_Init(&argc, &argv); MPI_Comm_rank(MPI_COMM_WORLD, &taskid); MPI_Comm_size(MPI_COMM_WORLD, &numtasks); int rows, offset, remainPart, orginalRows, height, width; int **a; // int a[S][S]; if(taskid ==

I've got an MPI program consisting of one master process that hands off commands to a bunch of slave processes. Upon receiving a command, a slave just calls system() to do it. While the slaves are waiting for a command, they are consuming 100% of their respective CPUs. It appears that Probe() is sitting in a tight loop, but that's only a guess. What do you think might be causing this, and what could I do to fix it? Here's the code in the slave process that waits for a command. Watching the log and the top command at the same time suggests that when the slaves are consuming their CPUs, they are

I write an OpenMPI application which consists of a server and a client part which are launched separately: me@server1:~> mpirun server and me@server2:~> mpirun client server creates a port using MPI_Open_port . The question is: Does OpenMPI have a mechanism to communicate the port to client ? I suppose that MPI_Publish_name and MPI_Lookup_name doesn't work here because server wouldn't know to which other computer the information should be sent. To me, it looks like only processes which were started using a single mpirun can communicate with MPI_Publish_name . I also found ompi-server , but the

How do I assign 2 MPI processes per core? For example, if I do mpirun -np 4 ./application then it should use 2 physical cores to run 4 MPI processes (2 processes per core). I am using Open MPI 1.6. I did mpirun -np 4 -nc 2 ./application but wasn't able to run it. It complains mpirun was unable to launch the specified application as it could not find an executable: Hristo Iliev orterun (the Open MPI SPMD/MPMD launcher; mpirun/mpiexec are just symlinks to it) has some support for process binding but it is not flexible enough to allow you to bind two processes per core. You can try with -bycore