test.c

#include <stdio.h>  
#include <stdlib.h>  
#include <sys/time.h>  
#include <time.h>  
#include <sched.h>  
#include <sys/types.h>  
#include <unistd.h>      //pipe()  

/**
 * @brief This program demonstrates context switching between two processes using pipes.
 * 
 * The program creates two pipes, `fd` and `p`, and forks a child process. 
 * The child process reads from `fd[0]` and writes to `p[1]`, while the parent process 
 * writes to `fd[1]` and reads from `p[0]`. This creates a loop where the child and parent 
 * processes alternate sending and receiving characters through the pipes.
 * 
 * The program also sets the scheduling policy of both processes to `SCHED_FIFO` using 
 * `sched_setscheduler()` function. It measures the time before and after the context 
 * switch using `gettimeofday()` function and prints the results.
 * 
 * @return 0 on success.
 */
int main()  
{  
    int x, i, fd[2], p[2];  
    char send    = 's';  
    char receive;  
    pipe(fd);  
    pipe(p);  
    struct timeval tv;  
    struct sched_param param;  
    param.sched_priority = 0;  
  
    while ((x = fork()) == -1); 
    if (x==0) {  
        sched_setscheduler(getpid(), SCHED_FIFO, &param);  
        gettimeofday(&tv, NULL);  
        printf("Before Context Switch Time%u s, %u us\n", tv.tv_sec, tv.tv_usec);  
        for (i = 0; i < 10000; i++) {  
            read(fd[0], &receive, 1);  
            write(p[1], &send, 1);  
        }  
        exit(0);  
    }  
    else {  
        sched_setscheduler(getpid(), SCHED_FIFO, &param);  
        for (i = 0; i < 10000; i++) {  
            write(fd[1], &send, 1);  
            read(p[0], &receive, 1);  
        }  
        gettimeofday(&tv, NULL);  
        printf("After Context SWitch Time%u s, %u us\n", tv.tv_sec, tv.tv_usec);  
    }  
    return 0;  
}