/**
When the scheme is set to RR, called when the quantum timer has expired
on a core.
If any job should be scheduled to run on the core free'd up by
the quantum expiration, return the job_number of the job that should be
scheduled to run on core core_id.
@param core_id the zero-based index of the core where the quantum has expired.
@param time the current time of the simulator.
@return job_number of the job that should be scheduled on core cord_id
@return -1 if core should remain idle
*/
int scheduler_quantum_expired(int core_id, int time)
{
/**
* The current assumption is that this function works similarly for
* every scheme. Preemption occurs when a new job arrives.
*/
job_t *done; //the finished job
job_t *next = NULL;
//The core is now idle
ugh->corelist[core_id] = 0;
int index;
for(index = 0; index < priqueue_size(ugh->thing); index++)
if( ((job_t *) priqueue_at(ugh->thing, index))->core == core_id) {
done = (job_t *) priqueue_at(ugh->thing, index);
break;
}
priqueue_remove_at(ugh->thing, index);
//temporal statistics are calculated only when a job is done
// ugh->total_response_time += done->response_time;
ugh->total_turnaround_time += time - done->time;
// ugh->total_waiting_time += done->waiting_time;
done->when_preempted = time;
done->is_running = 0;
done->core = -1;
done->running_time = done->running_time - time + done->start_time;
done->time = time;
priqueue_offer(ugh->thing, done);
for(index = 0; index < priqueue_size(ugh->thing); index++)
if( !((job_t *) priqueue_at(ugh->thing, index))->is_running) {
next = (job_t *) priqueue_at(ugh->thing, index);
break;
}
if(next) {
next->core = core_id;
ugh->corelist[core_id] = 1;
next->is_running = 1;
next->waiting_time += time - next->when_preempted;
if(!next->firsty) {
next->firsty = 1;
next->first_time = time;
next->response_time = time - next->time;
}
next->start_time = time;
return next->job_number;
}
//The core should remain idle, such as for instance when the queue is empty.
return -1;
}
/**
Retrieves and removes the head of this queue, or NULL if this queue
is empty.
@param q a pointer to an instance of the priqueue_t data structure
@return the head of this queue
@return NULL if this queue is empty
*/
void *priqueue_poll(priqueue_t *q)
{
if (q->head == NULL){
return NULL;
}
return priqueue_remove_at(q,0);
}
/**
Removes all instances of ptr from the queue.
This function should not use the comparer function, but check if the data contained in each element of the queue is equal (==) to ptr.
@param q a pointer to an instance of the priqueue_t data structure
@param ptr address of element to be removed
@return the number of entries removed
*/
int priqueue_remove(priqueue_t *q, void *ptr)
{
struct node *tmp = q->head;
int i = 0;
int num = 0;
while(tmp != NULL){
if(tmp->data == ptr){
tmp=tmp->next;
priqueue_remove_at(q,i);
num++;
}else{
i++;
tmp=tmp->next;
}
}
return num;
}
int main()
{
priqueue_t q, q2;
priqueue_init(&q, compare1);
priqueue_init(&q2, compare2);
/* Pupulate some data... */
int *values = malloc(100 * sizeof(int));
int i;
for (i = 0; i < 100; i++)
values[i] = i;
/* Add 5 values, 3 unique. */
priqueue_offer(&q, &values[12]);
priqueue_offer(&q, &values[13]);
priqueue_offer(&q, &values[14]);
priqueue_offer(&q, &values[12]);
priqueue_offer(&q, &values[12]);
printf("Total elements: %d (expected 5).\n", priqueue_size(&q));
priqueue_print(&q);
int val_removed = *((int *)priqueue_remove_at(&q, 4));
printf("Element removed: %d (expected 14).\n", val_removed);
printf("Total elements: %d (expected 4).\n", priqueue_size(&q));
int val = *((int *)priqueue_poll(&q));
printf("Top element: %d (expected 12).\n", val);
printf("Total elements: %d (expected 3).\n", priqueue_size(&q));
int vals_removed = priqueue_remove(&q, &values[12]);
printf("Elements removed: %d (expected 2).\n", vals_removed);
printf("Total elements: %d (expected 1).\n", priqueue_size(&q));
priqueue_print(&q);
priqueue_offer(&q, &values[10]);
priqueue_offer(&q, &values[30]);
priqueue_offer(&q, &values[20]);
printf("Total elements: %d (expected 4).\n", priqueue_size(&q));
priqueue_offer(&q2, &values[10]);
priqueue_offer(&q2, &values[30]);
priqueue_offer(&q2, &values[20]);
printf("Total elements: %d (expected 3).\n", priqueue_size(&q2));
printf("Elements in order queue (expected 10 13 20 30): ");
for (i = 0; i < priqueue_size(&q); i++)
printf("%d ", *((int *)priqueue_at(&q, i)) );
printf("\n");
printf("Elements in reverse order queue (expected 30 20 10): ");
for (i = 0; i < priqueue_size(&q2); i++)
printf("%d ", *((int *)priqueue_at(&q2, i)) );
printf("\n");
priqueue_destroy(&q2);
priqueue_destroy(&q);
printf("Total elements q: %d (expected 0).\n", priqueue_size(&q));
printf("Total elements q2: %d (expected 0).\n", priqueue_size(&q2));
free(values);
return 0;
}
/**
Destroys and frees all the memory associated with q.
@param q a pointer to an instance of the priqueue_t data structure
*/
void priqueue_destroy(priqueue_t *q)
{
while(priqueue_remove_at(q,0) != NULL){
}
//free(q);
}
int scheduler_new_job(int job_number, int time, int running_time, int priority)
{
ugh->num_jobs++;
job_t *job = (job_t *) malloc(sizeof(job_t));
job->job_number = job_number;
job->priority = priority;
job->running_time = running_time;
job->time = time;
job->start_time = -1;
job->first_time = -1;
job->is_running =
job->firsty =
job->response_time =
job->waiting_time = 0;
job->when_preempted = time;
job->core = -1; //no core has been assigned to it yet
priqueue_offer(ugh->thing, job);
//Look for an idle core
int i;
for(i=0; i<ugh->num_cores; i++)
if(!ugh->corelist[i]) {
ugh->corelist[i] = 1; //The core is now in use
job->is_running = 1; //is being performed
job->firsty = 1;
job->start_time = time;
job->first_time = time;
job->response_time = 0;//time - job->time + 1;
return job->core = i; //The id of the core to which job has been assigned.
}
if(ugh->sch/3 + ugh->sch%3 < 2 || ugh->sch == RR) return -1; //returns if nonpreemptive or RR
/**
* If there be no idle cores, use the power of preemption.
* (Nonpreemptive jobs return -1 at the end of this function.)
*/
//rt = REMAINING time, not running time; pt = priority
int index, rt, lrt = -1, thindex = -1, pt, mpt = -1;
job_t *curr;
/**
* PREEMPTIVE SHORTEST JOB FIRST:
* This will preempt the job that is running with the largest
* remaining time, if that time be greteater than the running
* time for this job. It will additionally reschedule the
* preempted job with updated running time.
*
* One must remember that these schemes are like the nonpreemptive
* ones insomuch as there be no conflicts with jobs that are running.
*/
if(ugh->sch == PSJF) {
/**
* Finding the largest remaining time of a running job and the index of the job
* to which it belongs.
*/
for(index = 0; index < priqueue_size(ugh->thing); index++)
if( ((job_t *) priqueue_at(ugh->thing, index))->is_running) {
curr = (job_t *) priqueue_at(ugh->thing, index);
if(lrt < (rt = curr->running_time - time + curr->start_time)) {
lrt = rt;
thindex = index;
}
}
}
/**
* PREEMPTIVE PRIORITY THING:
* Similar to PSJF, except the basis for preemption is priority.
*/
else if(ugh->sch == PPRI) {
/**
* Finding the largest priority number or lowest priority of a running job
* and the index of the job to which it belongs.
*/
for(index = 0; index < priqueue_size(ugh->thing); index++)
if( ((job_t *) priqueue_at(ugh->thing, index))->is_running) {
curr = (job_t *) priqueue_at(ugh->thing, index);
if(mpt <= (pt = curr->priority)) {
lrt = curr->running_time - time + curr->start_time;
mpt = pt;
thindex = index;
}
}
}
/**
* thindex is the index of the job with the largest remaining time/priority number
* that is currently running. It is this job that the new job must
* attempt to preempt.
*/
curr = priqueue_at(ugh->thing, thindex);
if( (ugh->sch == PSJF && job->running_time < lrt) ||
(ugh->sch == PPRI && job->priority < mpt) ) {
job->core = curr->core; //assign job to run on the preempted job's core
priqueue_remove_at(ugh->thing, thindex); //remove curr from the queue in order to fix its stats
curr->running_time = lrt; //change its running time to be the remaining time
curr->is_running = 0; //remember that it is no longer running
job->is_running = job->firsty = 1;
job->response_time = 0; //time - job->time + 1;
curr->core = -1; //it is not running on any cores
curr->when_preempted = time;
if(curr->first_time == time) {
curr->start_time = -1;
curr->firsty = 0;
}
job->start_time = time;
priqueue_offer(ugh->thing, curr); //put it back into the priority queue
return job->core; //return the core on which job is to be run
}
return -1; //job needs to wait in line like everyone else
}
