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 void dm_start_request(struct mapped_device *md, struct request *orig)
{
if (!orig->q->mq_ops)
blk_start_request(orig);
else
blk_mq_start_request(orig);
atomic_inc(&md->pending[rq_data_dir(orig)]);
if (md->seq_rq_merge_deadline_usecs) {
md->last_rq_pos = rq_end_sector(orig);
md->last_rq_rw = rq_data_dir(orig);
md->last_rq_start_time = ktime_get();
}
if (unlikely(dm_stats_used(&md->stats))) {
struct dm_rq_target_io *tio = tio_from_request(orig);
tio->duration_jiffies = jiffies;
tio->n_sectors = blk_rq_sectors(orig);
dm_stats_account_io(&md->stats, rq_data_dir(orig),
blk_rq_pos(orig), tio->n_sectors, false, 0,
&tio->stats_aux);
}
/*
* Hold the md reference here for the in-flight I/O.
* We can't rely on the reference count by device opener,
* because the device may be closed during the request completion
* when all bios are completed.
* See the comment in rq_completed() too.
*/
dm_get(md);
}
static void
deadline_move_request(struct deadline_data *dd, struct request *rq)
{
const int data_dir = rq_data_dir(rq);
dd->next_rq[READ] = NULL;
dd->next_rq[WRITE] = NULL;
dd->next_rq[data_dir] = deadline_latter_request(rq);
dd->last_sector = rq_end_sector(rq);
deadline_move_to_dispatch(dd, rq);
}
/*
* move an entry to dispatch queue
*/
static void
deadline_move_request(struct deadline_data *dd, struct request *rq)
{
const int data_dir = rq_data_dir(rq);
dd->next_rq[READ] = NULL;
dd->next_rq[WRITE] = NULL;
dd->next_rq[data_dir] = deadline_latter_request(rq);
dd->last_sector = rq_end_sector(rq);
/*
* take it off the sort and fifo list, move
* to dispatch queue
*/
deadline_move_to_dispatch(dd, rq);
}
static int cscan_dispatch(struct request_queue *q, int force)
{
struct request *rq;
struct cscan_data *cd = q->elevator->elevator_data;
struct rb_node *node = rb_first(&(cd->sort_list[cd->curr]));
if(!node) {
cd->curr = 1-cd->curr;
node = rb_first(&(cd->sort_list[cd->curr]));
}
if(node) {
rq = rb_entry_rq(node);
cd->last_sector = rq_end_sector(rq);
elv_rb_del(&(cd->sort_list[cd->curr]), rq);
elv_dispatch_add_tail(q, rq);
return 1;
}
return 0;
}
//if shouldBuild dirty bit is set, combine c-scan lists into one list and buildTable
//use headposition and table build to make best path
//turn dirty shouldBuild dirty bit off
//dispatch first guy in path
//set new head position
static int optimal_dispatch(struct request_queue *q, int force)
{
int size = 0, ndx = 1;
long cost1, cost2;
struct list_head *entry;
struct requestList *scan;
struct optimal_data *nd = q->elevator->elevator_data;
if(nd->shouldBuild){
//put everything in my cscan list into an array of requests
//in cscan order
entry = &nd->arrival_queue;
while(((entry = entry->next)!=&nd->arrival_queue)&&size<nd->max_requests){
nd->mylist[size] = list_entry_rq(entry);
size++;
}
if(size == 0){
nd->dispatchSize = 0;
nd->currentNdx = 0;
return 0;
}
//might be redundant
if(size > nd->max_requests)
size = nd->max_requests;
buildTable(nd->mylist, size, nd->C);
cost1 = ((size-1) + 1) * distance(blk_rq_pos(&nd->headpos), blk_rq_pos(nd->mylist[0])) + nd->C[0][size-1][0].cost;
cost2 = ((size-1) + 1) * distance(blk_rq_pos(&nd->headpos), blk_rq_pos(nd->mylist[size-1])) + nd->C[0][size-1][1].cost;
if(cost1 < cost2){
nd->dispatch_head[0] = nd->mylist[0];
//for each item in C[0][size-1][0]'s path, add to dispatch_head
scan = nd->C[0][size-1][0].head;
while(scan != NULL && scan->data != NULL){
nd->dispatch_head[ndx] = scan->data;
ndx++;
scan = scan->next;
}
}
else{
nd->dispatch_head[0] = nd->mylist[size-1];
scan = nd->C[0][size-1][1].head;
while(scan != NULL && scan->data != NULL){
nd->dispatch_head[ndx] = scan->data;
ndx++;
scan = scan->next;
}
}
nd->dispatchSize = size;
nd->currentNdx = 0;
nd->shouldBuild = 0;
}
/*
if (!list_empty(&nd->arrival_queue)) {
struct request *rq;
rq = list_entry(nd->arrival_queue.next, struct request, queuelist);
nd->headpos.__sector =rq_end_sector(rq);
list_del_init(&rq->queuelist);
elv_dispatch_add_tail(q, rq);
nd->currentNdx++;
return 1;
}
*/
if(nd->currentNdx < nd->dispatchSize){
struct request *rq;
rq = nd->dispatch_head[nd->currentNdx];
nd->headpos.__sector = rq_end_sector(rq);
list_del_init(&rq->queuelist);
elv_dispatch_add_tail(q, rq);
nd->currentNdx++;
return 1;
}
return 0;
}