/*
* row_dispatch_insert() - move request to dispatch queue
* @rd: pointer to struct row_data
* @rq: the request to dispatch
*
* This function moves the given request to the dispatch queue
*
*/
static void row_dispatch_insert(struct row_data *rd, struct request *rq)
{
struct row_queue *rqueue = RQ_ROWQ(rq);
row_remove_request(rd, rq);
elv_dispatch_sort(rd->dispatch_queue, rq);
if (rq->cmd_flags & REQ_URGENT) {
WARN_ON(rd->urgent_in_flight);
rd->urgent_in_flight = true;
}
rqueue->nr_dispatched++;
row_clear_rowq_unserved(rd, rqueue->prio);
row_log_rowq(rd, rqueue->prio,
" Dispatched request %p nr_disp = %d", rq,
rqueue->nr_dispatched);
if (rqueue->prio < ROWQ_REG_PRIO_IDX) {
rd->last_served_ioprio_class = IOPRIO_CLASS_RT;
if (row_regular_req_pending(rd))
rd->reg_prio_starvation.starvation_counter++;
if (row_low_req_pending(rd))
rd->low_prio_starvation.starvation_counter++;
} else if (rqueue->prio < ROWQ_LOW_PRIO_IDX) {
rd->last_served_ioprio_class = IOPRIO_CLASS_BE;
rd->reg_prio_starvation.starvation_counter = 0;
if (row_low_req_pending(rd))
rd->low_prio_starvation.starvation_counter++;
} else {
rd->last_served_ioprio_class = IOPRIO_CLASS_IDLE;
rd->low_prio_starvation.starvation_counter = 0;
}
}
static int greedy_dispatch(struct request_queue *q, int force) {
struct request* rq, next_upper, next_lower;
struct greedy_data *nd = q->elevator->elevator_data;
struct sector lower_sector, upper_sector;
if(list_empty(nd->lower_queue) && list_empty(nd->upper_queue)) return NULL;
if(list_empty(nd->lower_queue)) {
rq = greedy_next_upper(q, nd);
goto end;
}
if(list_empty(nd->upper_queue)) {
rq = greedy_next_lower(q, nd);
goto end;
}
next_lower = greedy_next_lower(nd);
next_upper = greedy_next_upper(nd);
lower_sector = blk_rq_pos(next_lower);
upper_sector = blk_rq_pos(next_upper);
if((upper_sector - nd->head_sector) < (nd->head_sector - lower_sector)) {
rq = next_upper;
goto end;
}
rq = next_lower;
end:
nd->head_sector = rq_end_sector(rq);
list_del_init(&rq->queuelist);
elv_dispatch_sort(q, rq);
return 1;
}
static int noop_dispatch(struct request_queue *q, int force)
{
struct noop_data *nd = q->elevator->elevator_data;
if (!list_empty(&nd->queue)) {
struct request *rq;
rq = list_entry(nd->queue.next, struct request, queuelist);
list_del_init(&rq->queuelist);
elv_dispatch_sort(q, rq);
return 1;
}
return 0;
}
static int noop_dispatch(struct request_queue *q, int force)
{
struct noop_data *nd = q->elevator->elevator_data;
struct request *rq;
rq = list_first_entry_or_null(&nd->queue, struct request, queuelist);
if (rq) {
list_del_init(&rq->queuelist);
elv_dispatch_sort(q, rq);
return 1;
}
return 0;
}
static int mpq_dispatch(struct request_queue *q, int force) {
struct mpq_data *nd = q->elevator->elevator_data;
struct request *rq;
unsigned long endTime, serveTime;
rq = list_first_entry_or_null(&nd->queue[0], struct request, queuelist);
if(rq) {
list_del_init(&rq->queuelist);
elv_dispatch_sort(q, rq);
endTime = jiffies;
serveTime = rq->fifo_time - endTime;
printk(KERN_ALERT "Dispatched from Queue 1 with ProcessID : %d : Time required %lu \n", q1, serveTime);
return 1;
}
else {
rq = list_first_entry_or_null(&nd->queue[1], struct request, queuelist);
if(rq) {
list_del_init(&rq->queuelist);
elv_dispatch_sort(q, rq);
endTime = jiffies;
serveTime = rq->fifo_time - endTime;
printk(KERN_ALERT "Dispatched from Queue 2 with ProcessID : %d : Time required %lu \n", q2, serveTime);
return 1;
}
else {
rq = list_first_entry_or_null(&nd->queue[2], struct request, queuelist);
if(rq) {
list_del_init(&rq->queuelist);
elv_dispatch_sort(q, rq);
endTime = jiffies;
serveTime = rq->fifo_time - endTime;
printk(KERN_ALERT "Dispatched from Queue 3 for general process: Time required %lu \n", serveTime);
return 1;
}
}
}
return 0;
}
static int sstf_dispatch(struct request_queue *q, int force)
{
struct sstf_data *nd = q->elevator->elevator_data;
if (!list_empty(&nd->queue)) {
struct request *nextrq, *prevrq, *rq;
nextrq = list_entry(nd->queue.next, struct request, queuelist);
prevrq = list_entry(nd->queue.prev, struct request, queuelist);
/* Check if there is only one element in list */
if (nextrq == prevrq) {
rq = nextrq;
} else {
if (nd->direction == HEAD_FWD) {
if (nextrq->sector > nd->head_pos) {
rq = nextrq;
} else {
nd->direction = HEAD_BCK;
rq = prevrq;
}
} else { /* Head is going backwards */
if (prevrq->sector < nd->head_pos) {
rq = prevrq;
} else {
nd->direction = HEAD_FWD;
rq = nextrq;
}
}
}
list_del_init(&rq->queuelist);
nd->head_pos = rq->sector + rq->nr_sectors;
elv_dispatch_sort(q, rq);
/* Debugging */
if(rq_data_dir(rq) == 0)
printk("[SSTF] dsp READ %lu\n",rq->sector);
else
printk("[SSTF] dsp WRITE %lu\n",rq->sector);
return 1;
}
return 0;
}
