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Page_Rank_improved.c
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Page_Rank_improved.c
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#include <stdio.h>
#include <stdlib.h>
#include<string.h>
#include <mpi.h>
typedef struct Node
{
int start_node;
int end_node;
float value;
struct Node *next;
} Node;
#define WEIGHT 0.85 // Real in (0, 1), best at 0.85
#define ERROR 0.000001 // Real in (0, +inf)
#define MASTER 0 // Rank of the master process
#define TAG 0 /* MPI message tag parameter */
int main(int argc, char *argv[]){
// Variables for MPI communication
int numtasks; /* number of MPI tasks */
int rank; /* my MPI task number */
int rc; /* return code */
MPI_Status status; /* MPI receive routine parameter */
// Variables for input file reading
//char filename[] = "./DEMO.txt"; /* file containing the list of the edges */
//char filename[] = "./web-NotreDame.txt"; /* file containing the list of the edges */
FILE *fp; /* file pointer */
char ch; /* reads the characters in the file */
char str[100]; /* buffer for storing file lines */
// Variables for page rank algorithm
int n, e; /* n: number of nodes e: number of edges */
int rows_num; /* number of rows managed by each process */
int remaining_rows; /* remainder of the division n/numtasks */
int* info; /* buffer for sending information from master to workers */
int fromnode, tonode; /* fromnode: start node of an edge tonode: end node of an edge */
int* out_degree; /* vector containing the out_degree of all nodes */
float* local_sub_page_ranks; /* sub page_ranks vector of a process */
float* complete_page_ranks; /* complete page_rankes vector, all processes have their copy */
//float* old_complete_page_ranks;
float teleport_probability; /* probability of the random walker to teleport on a random node */
Node** sparse_matrix_local; /* sparse matrix containing only the rows of the transition matrix managed by the process*/
Node *pointer; /* iterates over sparse_matrix_local */
Node *currNode;
int iterate; /* flag: checks if the algorithm is converging or not*/
float sum; /* result of the multiplication of a row of the transition matrix and the page rank vector */
float score_norm = 0; /* difference between two consecutive page ranks */
float local_score_norm = 0; /* difference between two consecutive page ranks in the single process */
float diff; /* difference between two elements of consecutive page ranks */
int min_rows_num; /* minimum number of rows managed by a process */
int max_rows_num; /* maximum number of rows managed by a process */
float* minarray; /* array of size min_rows_num; stores the rows managed by a process */
float* maxarray; /* array of size max_rows_num; stores the rows managed by a process */
// Variable for performance measures
double wallClock_start, wallClock_stop;
double MPItime_start,MPItime_end;
int firstnode;
int count = 0;
// MPI initialization
MPI_Init(&argc,&argv);
MPI_Comm_size(MPI_COMM_WORLD,&numtasks);
MPI_Comm_rank(MPI_COMM_WORLD,&rank);
info = malloc ( 2 * sizeof(int));
// MASTER CODE : read the input file
if(rank == MASTER){
if(strcmp("0",argv[2]) == 0)firstnode = 0;
else if (strcmp("1",argv[2]) == 0)firstnode = 1;
else firstnode = -1;
if(firstnode == -1){
printf("INVALID ARGUMENT %s %s \n",argv[1],argv[2]);
exit(1);
}
printf("DEBUG: MASTER open the file %s\n",argv[1]);
if ((fp = fopen(argv[1], "r")) == NULL){
fprintf(stderr, "[Error] cannot open file");
exit(1);
}
// Read the data set and get the number of nodes (n) and edges (e)
ch = getc(fp);
while (ch == '#'){
fgets(str, 100 - 1, fp);
sscanf(str, "%*s %d %*s %d", &n, &e); // number of nodes and edges
ch = getc(fp);
}
ungetc(ch, fp);
min_rows_num = n/numtasks;
max_rows_num = min_rows_num + 1;
minarray = malloc((min_rows_num + 1) * sizeof(float));
maxarray = malloc((max_rows_num + 1) * sizeof(float));
remaining_rows = n%numtasks;
info[1] = n;
//Prendo il wall clock time
//papi_Time_start = PAPI_get_real_usec();
//MPItime_start = MPI_Wtime();
// Send the rows number and the number of nodes to all WORKER
for(int i = 1; i < numtasks; i++){
if(i < remaining_rows) {
info[0] = max_rows_num;
MPI_Send(info, 2, MPI_INT, i, TAG, MPI_COMM_WORLD);
}
else{
info[0] = min_rows_num;
MPI_Send(info, 2, MPI_INT, i, TAG, MPI_COMM_WORLD);
}
}
if(remaining_rows != 0){
rows_num = max_rows_num;
}else{
rows_num = min_rows_num;
}
sparse_matrix_local = malloc(rows_num * sizeof(Node *));
for (int k = 0; k < rows_num; k++){
sparse_matrix_local[k] = NULL;
}
}
// WORKER : receive the values of the edges
else{
MPI_Recv(info, 2, MPI_INT, MASTER, TAG, MPI_COMM_WORLD,MPI_STATUS_IGNORE);
rows_num = info[0];
sparse_matrix_local = malloc(rows_num * sizeof(Node *));
n = info[1];
for (int k = 0; k < rows_num; k++){
sparse_matrix_local[k] = NULL;
}
}
// Creation of the array for the out_degree of all nodes
out_degree = malloc(n * sizeof(int));
// Creation of the sub page_ranks vector for a process
local_sub_page_ranks = malloc((rows_num + 1) * sizeof(float));
// Creation of the complete page_ranks vector
complete_page_ranks = malloc((n+1) * sizeof(float));
//old_complete_page_ranks = malloc((n+1) * sizeof(float));
for (int k = 0; k < n; k++){
out_degree[k] = 0;
}
info[0] = 0; // from node
info[1] = 0; // to node
if (rank == MASTER){
while (!feof(fp)){
fscanf(fp, "%d%d", &fromnode, &tonode);
if(firstnode == 1){
fromnode=fromnode -1 ;
tonode=tonode-1;
}
info[0] = fromnode;
info[1] = tonode;
int dest = tonode % numtasks;
if (dest != MASTER){
MPI_Send(info, 2, MPI_INT, dest, TAG, MPI_COMM_WORLD);
}
else{
Node * NuovoArco = malloc(sizeof(Node));
NuovoArco->start_node = fromnode;
NuovoArco->end_node = tonode;
NuovoArco->value = 1;
// INSERIMENTO IN TESTA
NuovoArco->next = sparse_matrix_local[(tonode - rank) / numtasks];
sparse_matrix_local[(tonode - rank) / numtasks] = NuovoArco;
}
// use fromnode and tonode as index
out_degree[fromnode]++;
}
// Send the edges
info[0] = -1;
info[1] = -1;
for(int i = 1; i < numtasks; i++){
MPI_Send(info, 2, MPI_INT, i, TAG, MPI_COMM_WORLD);
}
// Send the out_degree array
for(int i = 1; i < numtasks; i++){
MPI_Send(out_degree, n, MPI_INT, i, TAG, MPI_COMM_WORLD);
}
}
else{ // WORKER receive edge code
MPI_Recv(info, 2, MPI_INT, MASTER, TAG, MPI_COMM_WORLD,
MPI_STATUS_IGNORE);
// Check if the master doesn't reach the eof
while(info[0] != -1 && info[1] != -1){
fromnode = info[0];
tonode = info[1];
Node * NuovoArco = malloc(sizeof(Node));
NuovoArco->start_node = fromnode;
NuovoArco->end_node = tonode;
NuovoArco->value = 1;
// INSERIMENTO IN TESTA
NuovoArco->next = sparse_matrix_local[(tonode - rank) / numtasks];
sparse_matrix_local[(tonode - rank) / numtasks] = NuovoArco;
// Receive the new edge
MPI_Recv(info, 2, MPI_INT, 0, TAG, MPI_COMM_WORLD,
MPI_STATUS_IGNORE);
}
MPI_Recv(out_degree, n, MPI_INT, MASTER, TAG, MPI_COMM_WORLD,
MPI_STATUS_IGNORE);
}
if(rank==MASTER){
MPItime_start = MPI_Wtime();
}
teleport_probability = (1 - WEIGHT) / (float)n;
for (int i = 0; i < n; i++){
if(i<rows_num){
local_sub_page_ranks[i] = 1.0 / (float)n;
pointer = sparse_matrix_local[i];
// Update the value of the pointer
while (pointer != NULL){
pointer->value = (WEIGHT / (float)out_degree[pointer->start_node]);
pointer = pointer->next;
}
}
complete_page_ranks[i] = 1.0 / (float)n;
}
iterate = 1;
while(iterate ){
if(rank==MASTER)count++;
/*
printf("\nI'M THE PROCESS %d AND THIS IS MY PAGE RANK IN THE FIRST WHILE BEFORE CALCULUS AT ITERATION %d:\n", rank, count);
for (int i = 0; i < n; i++){
printf("IN PROCESS %d THE PAGE RANK OF NODE %d IS : %0.50f \n", rank, i , complete_page_ranks[i]);
}
*/
local_score_norm = 0;
for (int i = 0,k=rank; i < rows_num;i++){
sum = 0.0;
currNode = sparse_matrix_local[i];
//printf("\nMULTIPLICATION ROW %d AT %d ITERATION (1ST WHILE)\n", i, count);
while (currNode!=NULL){
sum += (complete_page_ranks[currNode->start_node] * currNode->value);
//printf("%0.5f * %0.5f = %0.5f\n", complete_page_ranks[currNode->start_node], currNode->value, complete_page_ranks[currNode->start_node] * currNode->value);
currNode = currNode->next;
}
//printf("row %d finalsum = %f\n",i,sum);
local_sub_page_ranks[i] = sum + teleport_probability;
// take the absolute value of the error
diff = local_sub_page_ranks[i] - complete_page_ranks[k];
if (diff < 0){
diff = -diff;
}
// sum to the score_norm
float temp = local_score_norm + diff;
local_score_norm += diff;
// update the round robin index for moving in complete_page_ranks
k += numtasks;
}
// MASTER update the page rank and valuete the error
if (rank == MASTER){
score_norm = local_score_norm;
for (int sender_rank = 1 ; sender_rank < numtasks;sender_rank++){
if(sender_rank < remaining_rows){
MPI_Recv(maxarray,max_rows_num + 1, MPI_FLOAT, sender_rank, TAG, MPI_COMM_WORLD,MPI_STATUS_IGNORE);
for( int k=0,i= sender_rank; k<max_rows_num ; k++){
complete_page_ranks[i] = maxarray[k];
i=i+numtasks;
}
score_norm += maxarray[max_rows_num];
}else{
MPI_Recv(minarray,min_rows_num+1, MPI_FLOAT, sender_rank, TAG, MPI_COMM_WORLD,MPI_STATUS_IGNORE);
for( int k=0, i= sender_rank; k<min_rows_num ; k++){
complete_page_ranks[i] = minarray[k];
i=i+numtasks;
}
score_norm += minarray[min_rows_num];
}
}
for (int i = 0,k = 0 ; i<rows_num;i++){
complete_page_ranks[k]=local_sub_page_ranks[i];
k += numtasks;
}
/*
printf("\nI'M THE PROCESS %d AND THIS IS MY PAGE RANK IN THE FIRST WHILE AFTER CALCULUS AT ITERATION %d:\n", rank, count);
for (int i = 0; i < n; i++){
printf("IN PROCESS %d THE PAGE RANK OF NODE %d AT ITERATION %d IS : %0.50f \n", rank, i , count, complete_page_ranks[i]);
}
printf("\nI'M THE PROCESS %d AND THIS IS MY SCORE NORM AT ITERATION %d: %0.5f\n", rank, count, score_norm);
*/
if(score_norm <= 0.001) {
iterate = 0;
}
complete_page_ranks[n] = iterate;
// Send the new old_page_rank value to all worker
for(int i=1; i<numtasks; i++){
MPI_Send(complete_page_ranks, n+1, MPI_FLOAT, i, TAG, MPI_COMM_WORLD);
}
}
// WORKERS send the new page_rank values
else{
local_sub_page_ranks[rows_num]=local_score_norm;
MPI_Send(local_sub_page_ranks, rows_num+1, MPI_FLOAT, 0, TAG, MPI_COMM_WORLD);
MPI_Recv(complete_page_ranks, n+1, MPI_FLOAT, 0, TAG, MPI_COMM_WORLD,MPI_STATUS_IGNORE);
iterate = complete_page_ranks[n];
}
}
/*
if(rank == MASTER){
if(strcmp(argv[1],"DEMO.txt")==0){
for (int i = 0; i < n; i++){
printf("THE PAGE RANKE OF NODE %d IS : %0.25f \n", i , complete_page_ranks[i]);
}
}
}
*/
//ora andiamo in parallelo
iterate = 1;
/*for ( int i =0; i < n;i++){
old_complete_page_ranks[i]=complete_page_ranks[i];
}*/
int count2=0;
while ( iterate){
local_score_norm = 0;
if(rank==MASTER)count2++;
/*
printf("\nI'M THE PROCESS %d AND THIS IS MY PAGE RANK IN THE SECOND WHILE BEFORE CALCULUS AT ITERATION %d:\n", rank, count2);
for (int i = 0; i < n; i++){
printf("IN PROCESS %d THE PAGE RANK OF NODE %d IS : %0.50f \n", rank, i , complete_page_ranks[i]);
}
*/
for (int i = 0,k=rank; i < rows_num;i++){
sum = 0.0;
currNode = sparse_matrix_local[i];
//printf("\nMULTIPLICATION ROW %d AT %d ITERATION (2ND WHILE)\n", i, count2);
while (currNode!=NULL){
sum += (complete_page_ranks[currNode->start_node] * currNode->value);
//printf("%0.5f * %0.5f = %0.5f\n", complete_page_ranks[currNode->start_node], currNode->value, complete_page_ranks[currNode->start_node] * currNode->value);
currNode = currNode->next;
}
//printf("row %d finalsum = %f\n",i,sum);
local_sub_page_ranks[i] = sum + teleport_probability;
// take the absolute value of the error
diff = local_sub_page_ranks[i] - complete_page_ranks[k];
if (diff < 0){
diff = -diff;
}
// sum to the score_norm
float temp = local_score_norm + diff;
local_score_norm += diff;
// update the round robin index for moving in complete_page_ranks
k += numtasks;
}
for (int i = 0,k=rank; i < rows_num;i++){
complete_page_ranks[k]=local_sub_page_ranks[i];
k += numtasks;
}
/*
printf("\nI'M THE PROCESS %d AND THIS IS MY PAGE RANK IN THE SECOND WHILE AFTER CALCULUS AT ITERATION %d:\n", rank, count2);
for (int i = 0; i < n; i++){
printf("IN PROCESS %d THE PAGE RANK OF NODE %d AT ITERATION %d IS : %0.50f \n", rank, i , count2, complete_page_ranks[i]);
}
printf("\nI'M THE PROCESS %d AND THIS IS MY LOCAL SCORE NORM AT ITERATION %d: %0.5f\n", rank, count2, local_score_norm);
*/
if(local_score_norm <= ERROR){
iterate = 0;
}
}
//convergiamo per l'ultima volta
if (rank == MASTER){
score_norm = 0.0;
for (int sender_rank = 1 ; sender_rank < numtasks;sender_rank++){
if(sender_rank < remaining_rows){
MPI_Recv(maxarray,max_rows_num + 1, MPI_FLOAT, sender_rank, TAG, MPI_COMM_WORLD,MPI_STATUS_IGNORE);
for( int k=0,i= sender_rank; k<max_rows_num ; k++){
complete_page_ranks[i] = maxarray[k];
i=i+numtasks;
}
score_norm += maxarray[max_rows_num];
}else{
MPI_Recv(minarray,min_rows_num+1, MPI_FLOAT, sender_rank, TAG, MPI_COMM_WORLD,MPI_STATUS_IGNORE);
for( int k=0, i= sender_rank; k<min_rows_num ; k++){
complete_page_ranks[i] = minarray[k];
i=i+numtasks;
}
score_norm += minarray[min_rows_num];
}
}
for (int i = 0,k = 0 ; i<rows_num;i++){
complete_page_ranks[k]=local_sub_page_ranks[i];
k += numtasks;
}
//printf("\nI'M THE PROCESS %d AND THIS IS MY FINAL SCORE NORM AT ITERATION %d: %0.5f\n", rank, score_norm);
}
// WORKERS send the new page_rank values
else{
//local_sub_page_ranks[rows_num]=local_score_norm;
MPI_Send(local_sub_page_ranks, rows_num+1, MPI_FLOAT, 0, TAG, MPI_COMM_WORLD);
//MPI_Recv(complete_page_ranks, n+1, MPI_FLOAT, 0, TAG, MPI_COMM_WORLD,MPI_STATUS_IGNORE);
}
MPItime_end = MPI_Wtime();
MPI_Finalize();
if(rank == MASTER){
if(strcmp(argv[1],"DEMO.txt")==0){
for (int i = 0; i < n; i++){
printf("THE PAGE RANK OF NODE %d IS : %0.6f \n", i , complete_page_ranks[i]);
}
}
//printf("%d iterazioni \n ",count);
//printf("%d seconde iterazioni\n",count2);
printf ("Tempo di esecuzione (secondi): %f\n", MPItime_end - MPItime_start);
}
return 0;
}