mpi Questions
2
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as I found no answer for my question so far and am on the edge of going crazy about the problem, I just ask the question tormenting my mind ;-)
I'm working on a parallelization of a node-eliminati...
3
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I wonder when do I need to use barrier? Do I need it before/after a scatter/gather for example? Or should OMPI ensure all processes have reached that point before scatter/gather-ing? Similarly, aft...
Spiritualist asked 9/11, 2012 at 9:59
1
I am writing a program using MPI. Each processor executes a for loop:
int main(int argc, char** argv) {
boost::mpi::environment env(argc, argv);
for( int i=0; i<10; ++i ) {
std::cout <&l...
5
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As stated in the question, what is the command that lists the current version of MPICH? I am running CentOS.
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I would like to know (in a few words) what are the main differences between OpenMP and MPI.
Infusorian asked 8/9, 2015 at 17:42
3
What is the difference between ranks and processes in MPI?
Phenacaine asked 22/3, 2011 at 23:26
1
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After much Googling, I have no idea what's causing this issue. Here it is:
I have a simple call to MPI_Allgather in my code which I have double, triple, and quadruple-checked to be correct (send/r...
1
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Am brand new to mpi4py. The calculate pi example from the Tutorial goes like so:
Master (or parent, or client) side:
#!/usr/bin/env python
from mpi4py import MPI
import numpy
import sys
comm = M...
1
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Ok let's start, I've a bit of confusion in my head.
SEND: it is blocking. The sender will waits until the receiver has posted the corresponding RECV.
SSEND: it is blocking and the sender will NOT...
Wayless asked 16/7, 2015 at 22:21
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I am using a sparse tensor array manipulation I built using dictionaries and Counters in Python. I would like to make it possible to use this array manipulation in parallel. The bottom line is that...
Prefrontal asked 13/7, 2015 at 16:19
2
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I trying to set up bunch of spawned processes into a single intracomm. I need to spawn separate processes into unique working directories since these subprocesses will write out a bunch of files. A...
1
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I want to do a Cholesky factorization in a distributed environment. For that purpose, I use pdpotrf(). However, I am struggling understanding the parameters needed by the function and they provide ...
Ancilin asked 19/6, 2015 at 11:55
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In working with parallel decompositions of matrices, I'm familiar with a block distribution, where we have (say) 4 processes, each with their own subregion of the matrix:
So for instance here we...
Respirable asked 26/6, 2015 at 15:26
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I searched to send a set object and the closest I found was with vector (it's different and don't work with set).
How can I send a set object in MPI_Send? (without using boost library) Anyone can ...
2
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I've discovered an MPI communicator called MPI_COMM_SELF. The problem is, I don't know, when is it useful. It appears to me, that just every process "thinks" about itself as root.
Could you explai...
Unrepair asked 28/5, 2015 at 15:43
1
I am trying to run some parallel optimization using PyOpt. The tricky part is that within my objective function, I want to run a C++ code using mpi as well.
My python script is the following:
#!...
1
I have the following code written in C with MPI:
#include <mpi.h>
#include <stdio.h>
int main(int argc, char *argv[])
{
int size, rank;
MPI_Status status;
int buf[1000];
MPI_Init...
2
I have a question about MPI_SENDRECV.
here is an example:
PROGRAM sendrecv
IMPLICIT NONE
INCLUDE "mpif.h"
INTEGER a,b,myrank,nprocs,ierr
integer istat(MPI_STATUS_SIZE)
CALL MPI_INIT(ierr)
C...
Baum asked 13/6, 2012 at 15:23
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I was writing a project using MPI for a parallel programming course, and decided to name one of my functions connect(). But whenever I tried to mpirun the program (using recent versions of Open MPI...
Naominaor asked 13/5, 2015 at 20:14
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I am new to parallel computing and just starting to try out MPI and Hadoop+MapReduce on Amazon AWS. But I am confused about when to use one over the other.
For example, one common rule of thumb ad...
Recognition asked 6/1, 2015 at 3:11
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(Suppose all the matrices are stored in row-major order.) An example that illustrate the problem is to distribute a 10x10 matrix over a 3x3 grid, so that the size of the sub-matrices in each node l...
Peggie asked 29/3, 2015 at 4:7
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A paper by Donzis & Aditya suggests, that it is possible to use a finite difference scheme that might have a delay in the stencil. What does this mean? A FD scheme might be used to solve the he...
Formal asked 10/10, 2014 at 12:20
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What exactly does MPI_IN_PLACE do when given as an argument to MPI_Scatter and how should it be used? I can't make sense of man MPI_Scatter:
When the communicator is an intracommunicator, you ca...
Brunt asked 2/4, 2015 at 14:36
4
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The Message Passing Interface APIs always use int as a type for count variables. For instance, the prototype for MPI_Send is:
int MPI_Send(const void* buf, int count, MPI_Datatype datatype, int de...
1
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I am having a problem using MPI_Scatterv in a parallel program. Here is how it is defined :
int MPI_Scatterv(const void *sendbuf, const int *sendcounts,
const int *displs, MPI_Datatype sendtype, ...
Catechol asked 29/3, 2015 at 12:57
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