prschedrun.c

A small program to simulate priority scheduling in Unix.

#define _XOPEN_SOURCE
#define __USE_XOPEN
#define __USE_SVID
#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/wait.h>
#include <sys/timeb.h>
#include <time.h>
#include <math.h>
#ifdef linux
#include <getopt.h>
#endif
#include <string.h>
#include "scheduler.h"


double pareto(double a, double k, double p);
void genData(int argc);

#define PRIORITIES 10		/* to change the number of priority levels */
                                /* do it here */
#define MAXTIME 2000
#define MINTIME  100

int main(void)
{
    init_q();               ///initializing the ready queues
    genData(20);            //use modified genData to generate Process data
    PCB_entry *PROCESS;
    PROCESS = schedule_next();  //get the next process scheduled into the variable pointer to a process.
    printf("The process scheduled next is %d ",PROCESS->proc_no);       // for debugging
    re_insert(PROCESS, 0);  //submit for reduction if used full quantum.
    list_q();               //check if any boosting is necessary
	exit(EXIT_SUCCESS);
}

/* James Broberg's pareto generator */

double pareto(double a, double k, double p) {
	double z;  /* Uniform random number from 0 to 1 */
	double rv; /* Random variable from Pareto dist to be generated  */

   do {
        z = drand48();
   }
   while ((z == 0) || (z == 1));

   /* Generate the bounded Pareto rv using the inversion method  */
   rv = -(z * pow(p, a) - z * pow(k, a) - pow(p, a)) / (pow(p, a) * pow(k, a));
   rv = pow(rv, (-1 / a));

   return rv;
}

void genData(int argc)
{
	struct timeb   *tp;
	struct timeb    TP;
	int             priority, job_number;
	int             distribution[(PRIORITIES + 2)];
	int             i;
	time_t          junk;

	for(i = 0; i < PRIORITIES +2 ; i++)
	  distribution[i] = 0;

	tp = &TP;       /* Using ftime get a random seed value */
	ftime(tp);

	srand48((long) TP.time * (long) time(&junk) * (long) TP.millitm);  /* seed the random number
	                                     * generator */
/*
	if (argc != 1) {
		fprintf(stderr, "Insufficient number of command line arguments\n\n");
		fprintf(stderr, "Usage: gen-data num\n\n");
		fprintf(stderr, "Where: num is the number of \"jobs\" to create\n");
		fprintf(stderr, "          valid values between 1 and 4096\n");
		fprintf(stderr, "\n");
		exit(EXIT_FAILURE);
	}
*/
	/* the command line parsing is basic on this program -- it
   * could be more sophisticated.
   */
	if (argc <= 0 || argc > 4096) {
		fprintf(stderr, "Selected number of elements to be\n");
		fprintf(stderr, "\tgenerated is out of range 1-4096\n");
		exit(EXIT_FAILURE);
	}

  /* ready to go -- this generates the data */

	for (job_number = 1; job_number <= argc; job_number++)
	{
		priority = (int) pareto(0.6 , 1, PRIORITIES + 1 );
		if ( priority < 1 ) priority = 1;
		if (priority > PRIORITIES ) priority = PRIORITIES;
		if ( priority >= 0 && priority  < PRIORITIES + 1 )
            distribution[priority - 1]++;
        PCB_entry *proc;
        int check = insert_new(proc);
        if (check == -1) printf("Error creating process %d ", priority);
        ready_q[priority-1]->initial_priority = priority;

		if ( priority < 5 )
		  {
                ready_q[priority-1]->time_required = (int) pareto ( 0.5, MINTIME, MAXTIME);
                ready_q[priority-1]->job_class = 1;
		  }
		else if ( priority < 9 )
		  {
                ready_q[priority-1]->time_required = (int) pareto ( 0.95, MINTIME, MAXTIME);
                ready_q[priority-1]->job_class = 1;
		  }
		else
		  {
                ready_q[priority-1]->time_required =  (int) pareto ( 0.8, MAXTIME / 2, MAXTIME * 3);
                ready_q[priority-1]->job_class = 1;
		  }
	}
}