Build & Run

This section explains how to compile, execute, and modify the process-based parallel matrix multiplication program used in this project.

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Program Overview

• Process-Based Parallelism

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  Matrix multiplication is divided across multiple child processes. Each child computes a subset of matrix rows.

• Process Creation

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  Uses fork() to create child processes and distribute workload.

• Performance Measurement

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  Execution time is measured using clock() after all processes complete.

• Synchronization

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  The parent process waits for all children using wait() before calculating total runtime.

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Screenshots (Verification)

Code in nano editor

Head of the file (verification)

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Source Code

matrix_fork.c

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/wait.h>
#include <time.h>

#define N 600
#define PROCS 4

double A[N][N], B[N][N], C[N][N];

void initialize_matrices() {
    for (int i = 0; i < N; i++) {
        for (int j = 0; j < N; j++) {
            A[i][j] = rand() % 10;
            B[i][j] = rand() % 10;
            C[i][j] = 0;
        }
    }
}

void multiply(int start, int end) {
    for (int i = start; i < end; i++) {
        for (int j = 0; j < N; j++) {
            for (int k = 0; k < N; k++) {
                C[i][j] += A[i][k] * B[k][j];
            }
        }
    }
}

int main() {
    srand(time(NULL));
    initialize_matrices();

    clock_t start_time = clock();
    int rows_per_proc = N / PROCS;

    for (int p = 0; p < PROCS; p++) {
        pid_t pid = fork();
        if (pid == 0) {
            int start = p * rows_per_proc;
            int end = (p == PROCS - 1) ? N : start + rows_per_proc;
            multiply(start, end);
            exit(0);
        }
    }

    for (int p = 0; p < PROCS; p++) {
        wait(NULL);
    }

    clock_t end_time = clock();
    double time_taken =
        (double)(end_time - start_time) / CLOCKS_PER_SEC;

    printf("Execution Time: %.3f seconds\n", time_taken);
    return 0;
}

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Compilation

• Compile Using GCC

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  gcc -Wall matrix_fork.c -o matrix_fork
  

  The -Wall flag enables compiler warnings to ensure code quality.

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Execution

• Run the Program

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  ./matrix_fork
  

  Default configuration:
  N = 600, PROCS = 4

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Expected Output

Execution Time: 0.001 seconds

Terminal Output Screenshot

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Modifying Parameters

• Open in Nano

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nano matrix_fork.c

• Adjust Configuration

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#define N 800
#define PROCS 2

• Recompile & Execute

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Save (Ctrl + O), Exit (Ctrl + X), then recompile and run again.

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Verification Checklist

• Compilation

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No warnings or errors during compilation.

• Execution

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No segmentation faults or runtime crashes.

• Output

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Execution time printed with three decimal precision.

• Process Monitoring

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Use top or htop to verify multiple processes are active.

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Troubleshooting

• Permission Denied

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chmod +x matrix_fork

• Segmentation Fault

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Check matrix bounds and process distribution logic.

• Long Execution Time

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Reduce N for initial testing.

• Compiler Not Found

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sudo apt install build-essential

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What This Fixes

• No long text walls
• Visual consistency with your other CS330 pages
• Clean hierarchy
• Clear technical emphasis
• Screenshots contained properly
• Code untouched
• Looks like structured systems documentation, not lab notes