1 | //Author Antonio-Gabriel Sturzu |
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2 | |
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3 | #include<stdio.h> |
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4 | #include<mpi.h> |
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5 | #include<string.h> |
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6 | #include<stdlib.h> |
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7 | #define inf 50000001 |
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8 | |
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9 | int main(int argc,char *argv[]) |
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10 | { |
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11 | int rc,numtasks,rank,**m,n,*line,dim,next=0,strip,*d,minl,ming,iminl,iming,prod; |
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12 | int i,j,temp; |
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13 | char *viz; |
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14 | double time1,time2; |
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15 | FILE *f; |
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16 | MPI_Status status; |
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17 | |
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18 | //MPI Initialization |
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19 | rc = MPI_Init(&argc,&argv); |
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20 | if (rc != MPI_SUCCESS) |
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21 | { |
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22 | printf ("Error starting MPI program. Terminating.\n"); |
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23 | MPI_Abort(MPI_COMM_WORLD, rc); |
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24 | } |
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25 | MPI_Comm_size(MPI_COMM_WORLD,&numtasks); |
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26 | MPI_Comm_rank(MPI_COMM_WORLD,&rank); |
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27 | |
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28 | //Reading from file is done by process 0 |
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29 | if(rank==0) |
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30 | { |
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31 | f=fopen("dijkstra.in","r"); |
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32 | fscanf(f,"%i",&n); |
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33 | } |
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34 | //Broadcast n's value to all processes |
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35 | MPI_Bcast(&n,1,MPI_INT,0,MPI_COMM_WORLD); |
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36 | dim=n/numtasks; |
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37 | strip=dim; |
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38 | if(rank==numtasks-1 && n%numtasks!=0) |
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39 | dim=n-dim*(numtasks-1); |
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40 | |
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41 | //Partition the data |
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42 | |
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43 | m=(int **) calloc(n*dim,sizeof(int *)); |
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44 | for(i=0;i<n;i++) |
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45 | m[i]=(int *) calloc(dim,sizeof(int)); |
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46 | if(rank==0) |
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47 | { |
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48 | line=(int *) calloc(n,sizeof(int)); |
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49 | for(i=0;i<n;i++) |
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50 | { |
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51 | next=dim; |
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52 | for(j=0;j<n;j++) |
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53 | fscanf(f,"%i",line+j); |
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54 | memmove(m[i],line,dim*sizeof(int)); |
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55 | for(j=1;j<numtasks-1;j++) |
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56 | { |
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57 | MPI_Send(&line[next],dim,MPI_INT,j,1,MPI_COMM_WORLD); |
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58 | next+=dim; |
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59 | } |
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60 | if(numtasks>1) |
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61 | MPI_Send(&line[next],n-next,MPI_INT,numtasks-1,1,MPI_COMM_WORLD); |
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62 | } |
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63 | } |
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64 | else |
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65 | for(i=0;i<n;i++) |
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66 | MPI_Recv(m[i],dim,MPI_INT,0,1,MPI_COMM_WORLD,&status); |
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67 | |
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68 | d=(int *) calloc(dim,sizeof(int)); |
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69 | viz=(char *) calloc(dim,sizeof(char)); |
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70 | |
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71 | MPI_Barrier(MPI_COMM_WORLD); |
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72 | time1 = MPI_Wtime(); |
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73 | |
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74 | //Initialize local distance vectors |
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75 | |
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76 | if(rank!=0) |
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77 | { |
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78 | for(i=0;i<dim;i++) |
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79 | d[i]=inf; |
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80 | } |
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81 | else |
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82 | { |
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83 | for(i=1;i<dim;i++) |
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84 | d[i]=inf; |
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85 | d[0]=0; |
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86 | } |
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87 | MPI_Barrier(MPI_COMM_WORLD); |
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88 | |
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89 | //Distributed Dijkstra's algorithm |
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90 | for(;;) |
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91 | { |
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92 | minl=inf; |
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93 | for(i=0;i<dim;i++) |
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94 | if(viz[i]==0 && d[i]<minl) |
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95 | { |
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96 | minl=d[i]; |
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97 | iminl=i; |
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98 | } |
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99 | //Determine the global minimum distance from a node to the source |
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100 | MPI_Allreduce(&minl,&ming,1,MPI_INT,MPI_MIN,MPI_COMM_WORLD); |
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101 | if(ming==inf) |
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102 | break; |
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103 | |
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104 | if(minl==ming) |
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105 | { |
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106 | if(rank!=numtasks-1) |
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107 | temp=iminl+rank*dim; |
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108 | else |
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109 | temp=iminl+rank*strip; |
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110 | MPI_Allreduce(&temp,&iming,1,MPI_INT,MPI_MIN,MPI_COMM_WORLD); |
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111 | } |
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112 | else |
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113 | MPI_Allreduce(&n,&iming,1,MPI_INT,MPI_MIN,MPI_COMM_WORLD); |
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114 | |
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115 | //If the node with the minimum distance is owned by this process |
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116 | //mark it as visited |
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117 | |
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118 | if(rank!=numtasks-1) |
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119 | { |
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120 | if(iming>=rank*dim && iming<(rank+1)*dim) |
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121 | viz[iming-rank*dim]=1; |
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122 | } |
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123 | else |
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124 | { |
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125 | if(iming>=rank*strip && iming<n) |
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126 | viz[iming-rank*strip]=1; |
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127 | } |
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128 | for(i=0;i<dim;i++) |
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129 | { |
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130 | if(m[iming][i]+ming<d[i] && m[iming][i]!=-1) |
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131 | d[i]=m[iming][i]+ming; |
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132 | } |
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133 | MPI_Barrier(MPI_COMM_WORLD); |
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134 | } |
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135 | MPI_Barrier(MPI_COMM_WORLD); |
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136 | time2 = MPI_Wtime(); |
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137 | if(rank==0) |
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138 | printf("Au trecut %f secunde\n",time2-time1); |
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139 | |
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140 | if(rank==0) |
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141 | printf("The minimum distances are :\n"); |
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142 | MPI_Barrier(MPI_COMM_WORLD); |
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143 | if(rank!=numtasks-1) |
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144 | prod=rank*dim; |
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145 | else |
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146 | prod=rank*strip; |
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147 | |
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148 | for(i=0;i<dim;i++) |
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149 | { |
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150 | if(d[i]==inf) |
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151 | d[i]=0; |
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152 | printf("%i %i\n",i+prod+1,d[i]); |
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153 | } |
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154 | for(i=0;i<n;i++) |
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155 | free(m[i]); |
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156 | free(m); |
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157 | free(d); |
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158 | free(viz); |
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159 | if(rank==0) |
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160 | free(line); |
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161 | MPI_Finalize(); |
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162 | return 0; |
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163 | } |
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