Mpich2: problems with communications

This is a discussion on Mpich2: problems with communications within the C++ Programming forums, part of the General Programming Boards category; I'm using mpich2 1.0.7. I installed and configured it on 2 machines, started daemons. The problems begin when I launch ...

  1. #1
    Registered User
    Join Date
    Jul 2008
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    5

    Question Mpich2: problems with communications

    I'm using mpich2 1.0.7. I installed and configured it on 2 machines, started daemons.
    The problems begin when I launch my program: first MPI_Bcast succeeds, but the second one (or any other communication function) hangs. Source code is attached.

    Also when I call MPI_Bcast, second machine deamon prints the following:
    F9Virtual64_mpdman_1 (run282): invalid msg from lhs; expecting ringsize got: {}

    Can anyone look at the code and tell me what's wrong?

    Code:
    #include <mpi.h>
    #include <stdio.h>
    #include <string.h>
    #include <math.h>
    #include <sys/time.h>
    
    int main(int arg_c, char** arg_v)
    {
    	if(arg_c<2)
    	{
    		printf("Input file not specified\n");
    		return 0;
    	}
    	if(MPI_Init(&arg_c, &arg_v)!=MPI_SUCCESS)
    	{
    		printf("MPI initialization failed\n");
    		return 0;
    	}
    	int ProcNum, ProcRank;
    	MPI_Comm_size(MPI_COMM_WORLD, &ProcNum);
    	MPI_Comm_rank(MPI_COMM_WORLD, &ProcRank);
    	
    	int size;
    	double e;
    	double* A;
    	double* b;
    	double* x, *xprev;
    	
    	FILE* f=0;
    	if(!ProcRank)
    	{
    		f=fopen(arg_v[1], "r");
    		if(!f)
    		{
    			printf("Error opening input file\n");
    			MPI_Finalize();
    			return 0;
    		}
    		fscanf(f, "%d", &size);
    		printf("Enter desired accuracy\n");
    		scanf("%lf", &e);
    	}
    	if(!ProcRank)
    		printf("Broadcasting matrix size\n");
    	if(MPI_Bcast(&size, 1, MPI_INT, 0, MPI_COMM_WORLD)!=MPI_SUCCESS)
    		if(!ProcRank)
    			printf("Failed to broadcast matrix size\n");
    	if(!ProcRank)
    		printf("Broadcasting accuracy\n");
    	if(MPI_Bcast(&e, 1, MPI_DOUBLE, 0, MPI_COMM_WORLD)!=MPI_SUCCESS)
    		if(!ProcRank)
    			printf("Failed to broadcast accuracy\n");
    	A=new double[size*size];
    	b=new double[size];
    	x=new double[size];
    	xprev=new double[size];
    	
    	memset(x, 0, size*sizeof(double));
    	memset(xprev, 0, size*sizeof(double));
    	
    	if(!ProcRank)
    	{
    		for(int i=0; i<size; i++)
    			for(int j=0; j<size; j++)
    				fscanf(f, "%lf", &(A[i*size+j]));
    		for(int i=0; i<size; i++)
    			fscanf(f, "%lf", &(b[i]));
    		fclose(f);
    	}
    	
    	if(!ProcRank)
    		printf("Waiting all processes to be initialized\n");
    	MPI_Barrier(MPI_COMM_WORLD);
    	
    	if(!ProcRank)
    		printf("Broadcasting matrix\n");
    	MPI_Bcast(A, size*size, MPI_DOUBLE, 0, MPI_COMM_WORLD);
    	if(!ProcRank)
    		printf("Broadcasting b\n");
    	MPI_Bcast(b, size, MPI_DOUBLE, 0, MPI_COMM_WORLD);
    	
    	double cursum, totalsum;
    	int fin, itercount=0;
    	
    	if(!ProcRank)
    		printf("Starting calculation\n");
    	struct timeval tv1, tv2;
    	gettimeofday(&tv1, 0);
    	do
    	{
    		MPI_Bcast(xprev, size, MPI_DOUBLE, 0, MPI_COMM_WORLD);
    		itercount++;
    		for(int i=0; i<size; i++)
    		{
    			int snum=(size)/ProcNum;
    			cursum=0.0;
    			totalsum=0.0;
    			for(int n=ProcRank*snum; n<((ProcRank==ProcNum-1)?(size):((ProcRank+1)*snum)); n++)
    			{
    				if(n<=i-1)
    					cursum+=A[i*size+n]*x[n];
    				else
    					cursum+=A[i*size+n]*xprev[n];
    			}
    			MPI_Barrier(MPI_COMM_WORLD);
    			MPI_Reduce(&cursum, &totalsum, 1, MPI_DOUBLE, MPI_SUM, 0, MPI_COMM_WORLD);
    			if(!ProcRank)
    			{
    				x[i]=xprev[i]-1.0/A[i*size+i]*(totalsum-b[i]);
    			}
    		}
    		if(!ProcRank)
    		{
    			fin=1;
    			for(int i=0; i<size; i++)
    				if(fabs(x[i]-xprev[i])>e)
    					fin=0;
    			if(!fin)
    				memcpy(xprev, x, size*sizeof(double));
    		}
    		MPI_Bcast(&fin, 1, MPI_INT, 0, MPI_COMM_WORLD);
    	}
    	while(!fin);
    	
    	gettimeofday(&tv2, 0);
    	
    	if(!ProcRank)
    	{
    		printf("Matrix A:\n");
    		for(int i=0; i<size; i++)
    		{
    			for(int j=0; j<size; j++)
    				printf("%lf ", A[i*size+j]);
    			printf("\n");
    		}
    		printf("\n");
    		printf("Line b:\n");
    		for(int i=0; i<size; i++)
    			printf("%lf ", b[i]);
    		printf("\n");
    		
    		printf("Iteration number: %d\n", itercount);
    		printf("Calculation time: %d microseconds\n", (tv2.tv_sec-tv1.tv_sec)*1000000+(tv2.tv_usec-tv1.tv_usec));
    		
    		printf("Results: \n");
    		for(int i=0; i<size; i++)
    			printf("x%d=%lf\n", i+1, x[i]);
    	}
    	
    	MPI_Barrier(MPI_COMM_WORLD);
    	
    	delete [] A;
    	delete [] b;
    	delete [] x;
    	delete [] xprev;
    	
    	MPI_Finalize();
    	
    	return 0;
    }
    Attached Files Attached Files

  2. #2
    Kernel hacker
    Join Date
    Jul 2007
    Location
    Farncombe, Surrey, England
    Posts
    15,677
    I'm sure there are mailing lists or forums for MPICH that would be better to answer this question.

    --
    Mats
    Compilers can produce warnings - make the compiler programmers happy: Use them!
    Please don't PM me for help - and no, I don't do help over instant messengers.

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