mpi Questions
1
If I use MPI, I have a number of processes specified when I run the main program. However I would like to start with one process and dynamically decide at runtime if and when I need more, to fork m...
Canaveral asked 14/3, 2012 at 17:33
1
I'm trying to create a log file from each processor and then send that to the root as a char array. I first send the length and then I send the data. The length sends fine, but the data is always g...
Gambrel asked 31/3, 2013 at 5:14
2
Solved
Assume that I have a very large array which I wish to send or receive with MPI (v1). In order to index this array, I use an unsigned long integer.
Now, all MPI function calls I have seen use int t...
2
Solved
How can I pass a the rank of a process as a tag to the mpi4py.MPI.COMM_WORLD.Send() function and correctly receive it with mpi4py.MPI.COMM_WORLD.Recv()?
I'm referring to the following code example...
1
Solved
Assume that i have a struct type as follows:
typedef struct {
float x, y, z;
float velocity;
int n, type;
} Particle;
I want to send it. I have to create an MPI_Type. I know 4 ways to do it. ...
1
Solved
I try to send a derived type to processors. The type contains object from other derived type. I started the example from Examples: Struct Derived Data Type. I add my code. The code is little long b...
1
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I am trying to generate two matrices A&B of size n, partition them into s*s sub-matrices and after scattering them through the processors, perform a multiplication between the block matrices. I...
Permissible asked 16/3, 2014 at 2:42
1
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I had to replace mpich2 with OpenMPI due to dependency of OpenFOAM on OpenMPI.
Earlier (when using mpich2) in my code I was using gethostname() function to get the name of the machine for debuggin...
Squinteyed asked 4/3, 2014 at 14:37
1
Solved
I'm writing a multi-threaded OpenMPI application, using MPI_Isend and MPI_Irecv from several threads to exchange hundreds of messages per second between ranks over InfiniBand RDMA.
Transfers are i...
Hekate asked 26/2, 2014 at 10:43
2
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What I understand is, that one master process sends a message to all other processes. All the other processes in return send a message to the master process. Would this be enough for a barrier to w...
Heyday asked 7/2, 2014 at 11:21
2
Solved
Need clarification to my understanding of isend and issend as given in Send Types
My understanding is that isend will return once the send buffer is free, i.e. when all the data has been released....
Teutonic asked 2/2, 2014 at 16:26
6
Is there a current Java MPI implementation. I have programmed in MPI a bit, and I enjoy programming in Java. I have seen this implementation in Java, but it seems dated. Is there a more up to date ...
1
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I have a program which uses MPI_Scatter() and MPI_Gather(). The program take as input an integer N and return the prime number from 2 to N. I create an array with the number from 2 to N and with th...
1
Solved
I have a malloc'd array of integers that I fill with MPI_Recv
MPI_Recv(d.current, n, MPI_INT, 0, TAG_CURRENT_ARRAY, MPI_COMM_WORLD, &status);
I have tested the value of d.current both before...
1
Solved
I have a large parallel (using MPI) simulation application which produces large amounts of data. In order to evaluate this data I use a python script.
What I now need to do is to run this applicat...
Ollie asked 13/1, 2014 at 11:24
2
Solved
Non-blocking sends/recvs return immediately in MPI and the operation is completed in the background. The only way I see that happening is that the current process/thread invokes/creates another pro...
Abnormal asked 12/1, 2014 at 7:35
2
Solved
I have a fairly large training matrix (over 1 billion rows, two features per row). There are two classes (0 and 1).
This is too large for a single machine, but fortunately I have about 200 MPI host...
Kilmer asked 10/1, 2014 at 18:47
1
Solved
I want to use MPI_Iprobe to test whether a message with a given tag is already pending.
However, the behaviour of MPI_Iprobe isn't quite as I was expecting.
In the example below, I send messages f...
Matteson asked 8/1, 2014 at 15:7
2
Solved
Here it is written that the output parameters of MPI_Cart_shift are ranks of the source and destination processes. However, in this tutorial (code below) what is returned as the source process is l...
Boneyard asked 28/12, 2013 at 9:54
1
Is there a way using MPI to let spawned processes communicate with all other actors in the MPI_WORLD and not only with the parent that spawned the process?
Now I have two main agents, the so-calle...
1
I have successfully set up the password less ssh between the servers and my computer.
There is a simple openMPI program which is running well on the single computer.
But ,unfortunately when i am tr...
Crosshead asked 11/7, 2013 at 22:22
1
Solved
Is there a way to make MPI just print the output from one (or a subset) of the processes? I know how to do that on code level, but I am wondering whether there is some way to specify this after the...
3
Solved
I have to implement an MPI program. There are some global variables (4 arrays of float numbers and other 6 single float variables) which are first inizialized by the main process reading data from ...
Bernice asked 11/12, 2013 at 18:39
1
I'm trying to run this sample hello world program with openmpi and mpirun on debian 7.
#include <stdio.h>
#include <mpi/mpi.h>
int main (int argc, char **argv) {
int nProcId, nProcNo...
2
Solved
I'm using MPICH2 to implement an "Odd-Even" Sort.
I did the implementation but when I randomize to each process his value,
the same number is randomized to all processes.
Here is the code for e...
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