[PATCH] deadline-iosched: remove elevator private drq request type
A big win, we now save an allocation/free on each request! With the previous rb/hash abstractions, we can just reuse queuelist/donelist for the FIFO data and be done with it. Signed-off-by: Jens Axboe <axboe@suse.de>
This commit is contained in:
Jens Axboe
Jens Axboe
parent
9e2585a8a2
commit
8840faa1ee
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@ -37,7 +37,7 @@ struct deadline_data {
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/*
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* next in sort order. read, write or both are NULL
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*/
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struct deadline_rq *next_drq[2];
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struct request *next_rq[2];
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unsigned int batching; /* number of sequential requests made */
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sector_t last_sector; /* head position */
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unsigned int starved; /* times reads have starved writes */
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@ -49,34 +49,14 @@ struct deadline_data {
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int fifo_batch;
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int writes_starved;
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int front_merges;
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mempool_t *drq_pool;
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};
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/*
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* pre-request data.
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*/
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struct deadline_rq {
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struct request *request;
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/*
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* expire fifo
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*/
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struct list_head fifo;
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unsigned long expires;
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};
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static void deadline_move_request(struct deadline_data *dd, struct deadline_rq *drq);
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static kmem_cache_t *drq_pool;
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#define RQ_DATA(rq) ((struct deadline_rq *) (rq)->elevator_private)
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static void deadline_move_request(struct deadline_data *, struct request *);
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#define RQ_RB_ROOT(dd, rq) (&(dd)->sort_list[rq_data_dir((rq))])
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#define DRQ_RB_ROOT(dd, drq) RQ_RB_ROOT((drq)->request)
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static void
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deadline_add_drq_rb(struct deadline_data *dd, struct request *rq)
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deadline_add_rq_rb(struct deadline_data *dd, struct request *rq)
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{
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struct rb_root *root = RQ_RB_ROOT(dd, rq);
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struct request *__alias;
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@ -84,45 +64,43 @@ deadline_add_drq_rb(struct deadline_data *dd, struct request *rq)
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retry:
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__alias = elv_rb_add(root, rq);
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if (unlikely(__alias)) {
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deadline_move_request(dd, RQ_DATA(__alias));
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deadline_move_request(dd, __alias);
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goto retry;
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}
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}
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static inline void
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deadline_del_drq_rb(struct deadline_data *dd, struct deadline_rq *drq)
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deadline_del_rq_rb(struct deadline_data *dd, struct request *rq)
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{
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struct request *rq = drq->request;
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const int data_dir = rq_data_dir(rq);
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if (dd->next_drq[data_dir] == drq) {
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if (dd->next_rq[data_dir] == rq) {
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struct rb_node *rbnext = rb_next(&rq->rb_node);
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dd->next_drq[data_dir] = NULL;
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dd->next_rq[data_dir] = NULL;
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if (rbnext)
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dd->next_drq[data_dir] = RQ_DATA(rb_entry_rq(rbnext));
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dd->next_rq[data_dir] = rb_entry_rq(rbnext);
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}
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elv_rb_del(RQ_RB_ROOT(dd, rq), rq);
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}
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/*
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* add drq to rbtree and fifo
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* add rq to rbtree and fifo
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*/
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static void
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deadline_add_request(struct request_queue *q, struct request *rq)
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{
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struct deadline_data *dd = q->elevator->elevator_data;
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struct deadline_rq *drq = RQ_DATA(rq);
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const int data_dir = rq_data_dir(drq->request);
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const int data_dir = rq_data_dir(rq);
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deadline_add_drq_rb(dd, rq);
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deadline_add_rq_rb(dd, rq);
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/*
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* set expire time (only used for reads) and add to fifo list
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*/
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drq->expires = jiffies + dd->fifo_expire[data_dir];
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list_add_tail(&drq->fifo, &dd->fifo_list[data_dir]);
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rq_set_fifo_time(rq, jiffies + dd->fifo_expire[data_dir]);
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list_add_tail(&rq->queuelist, &dd->fifo_list[data_dir]);
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}
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/*
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@ -130,11 +108,10 @@ deadline_add_request(struct request_queue *q, struct request *rq)
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*/
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static void deadline_remove_request(request_queue_t *q, struct request *rq)
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{
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struct deadline_rq *drq = RQ_DATA(rq);
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struct deadline_data *dd = q->elevator->elevator_data;
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list_del_init(&drq->fifo);
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deadline_del_drq_rb(dd, drq);
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rq_fifo_clear(rq);
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deadline_del_rq_rb(dd, rq);
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}
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static int
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@ -177,7 +154,7 @@ static void deadline_merged_request(request_queue_t *q, struct request *req,
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*/
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if (type == ELEVATOR_FRONT_MERGE) {
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elv_rb_del(RQ_RB_ROOT(dd, req), req);
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deadline_add_drq_rb(dd, req);
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deadline_add_rq_rb(dd, req);
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}
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}
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@ -185,20 +162,14 @@ static void
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deadline_merged_requests(request_queue_t *q, struct request *req,
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struct request *next)
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{
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struct deadline_rq *drq = RQ_DATA(req);
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struct deadline_rq *dnext = RQ_DATA(next);
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BUG_ON(!drq);
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BUG_ON(!dnext);
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/*
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* if dnext expires before drq, assign its expire time to drq
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* and move into dnext position (dnext will be deleted) in fifo
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* if next expires before rq, assign its expire time to rq
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* and move into next position (next will be deleted) in fifo
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*/
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if (!list_empty(&drq->fifo) && !list_empty(&dnext->fifo)) {
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if (time_before(dnext->expires, drq->expires)) {
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list_move(&drq->fifo, &dnext->fifo);
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drq->expires = dnext->expires;
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if (!list_empty(&req->queuelist) && !list_empty(&next->queuelist)) {
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if (time_before(rq_fifo_time(next), rq_fifo_time(req))) {
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list_move(&req->queuelist, &next->queuelist);
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rq_set_fifo_time(req, rq_fifo_time(next));
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}
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}
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@ -212,53 +183,50 @@ deadline_merged_requests(request_queue_t *q, struct request *req,
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* move request from sort list to dispatch queue.
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*/
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static inline void
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deadline_move_to_dispatch(struct deadline_data *dd, struct deadline_rq *drq)
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deadline_move_to_dispatch(struct deadline_data *dd, struct request *rq)
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{
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request_queue_t *q = drq->request->q;
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request_queue_t *q = rq->q;
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deadline_remove_request(q, drq->request);
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elv_dispatch_add_tail(q, drq->request);
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deadline_remove_request(q, rq);
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elv_dispatch_add_tail(q, rq);
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}
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/*
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* move an entry to dispatch queue
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*/
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static void
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deadline_move_request(struct deadline_data *dd, struct deadline_rq *drq)
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deadline_move_request(struct deadline_data *dd, struct request *rq)
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{
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struct request *rq = drq->request;
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const int data_dir = rq_data_dir(rq);
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struct rb_node *rbnext = rb_next(&rq->rb_node);
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dd->next_drq[READ] = NULL;
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dd->next_drq[WRITE] = NULL;
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dd->next_rq[READ] = NULL;
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dd->next_rq[WRITE] = NULL;
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if (rbnext)
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dd->next_drq[data_dir] = RQ_DATA(rb_entry_rq(rbnext));
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dd->next_rq[data_dir] = rb_entry_rq(rbnext);
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dd->last_sector = drq->request->sector + drq->request->nr_sectors;
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dd->last_sector = rq->sector + rq->nr_sectors;
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/*
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* take it off the sort and fifo list, move
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* to dispatch queue
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*/
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deadline_move_to_dispatch(dd, drq);
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deadline_move_to_dispatch(dd, rq);
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}
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#define list_entry_fifo(ptr) list_entry((ptr), struct deadline_rq, fifo)
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/*
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* deadline_check_fifo returns 0 if there are no expired reads on the fifo,
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* 1 otherwise. Requires !list_empty(&dd->fifo_list[data_dir])
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*/
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static inline int deadline_check_fifo(struct deadline_data *dd, int ddir)
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{
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struct deadline_rq *drq = list_entry_fifo(dd->fifo_list[ddir].next);
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struct request *rq = rq_entry_fifo(dd->fifo_list[ddir].next);
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/*
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* drq is expired!
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* rq is expired!
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*/
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if (time_after(jiffies, drq->expires))
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if (time_after(jiffies, rq_fifo_time(rq)))
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return 1;
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return 0;
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@ -273,21 +241,21 @@ static int deadline_dispatch_requests(request_queue_t *q, int force)
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struct deadline_data *dd = q->elevator->elevator_data;
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const int reads = !list_empty(&dd->fifo_list[READ]);
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const int writes = !list_empty(&dd->fifo_list[WRITE]);
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struct deadline_rq *drq;
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struct request *rq;
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int data_dir;
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/*
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* batches are currently reads XOR writes
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*/
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if (dd->next_drq[WRITE])
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drq = dd->next_drq[WRITE];
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if (dd->next_rq[WRITE])
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rq = dd->next_rq[WRITE];
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else
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drq = dd->next_drq[READ];
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rq = dd->next_rq[READ];
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if (drq) {
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if (rq) {
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/* we have a "next request" */
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if (dd->last_sector != drq->request->sector)
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if (dd->last_sector != rq->sector)
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/* end the batch on a non sequential request */
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dd->batching += dd->fifo_batch;
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@ -336,34 +304,33 @@ dispatch_find_request:
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if (deadline_check_fifo(dd, data_dir)) {
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/* An expired request exists - satisfy it */
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dd->batching = 0;
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drq = list_entry_fifo(dd->fifo_list[data_dir].next);
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rq = rq_entry_fifo(dd->fifo_list[data_dir].next);
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} else if (dd->next_drq[data_dir]) {
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} else if (dd->next_rq[data_dir]) {
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/*
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* The last req was the same dir and we have a next request in
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* sort order. No expired requests so continue on from here.
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*/
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drq = dd->next_drq[data_dir];
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rq = dd->next_rq[data_dir];
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} else {
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struct rb_node *n;
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struct rb_node *node;
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/*
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* The last req was the other direction or we have run out of
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* higher-sectored requests. Go back to the lowest sectored
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* request (1 way elevator) and start a new batch.
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*/
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dd->batching = 0;
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n = rb_first(&dd->sort_list[data_dir]);
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if (n)
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drq = RQ_DATA(rb_entry_rq(n));
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node = rb_first(&dd->sort_list[data_dir]);
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if (node)
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rq = rb_entry_rq(node);
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}
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dispatch_request:
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/*
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* drq is the selected appropriate request.
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* rq is the selected appropriate request.
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*/
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dd->batching++;
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deadline_move_request(dd, drq);
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deadline_move_request(dd, rq);
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return 1;
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}
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@ -383,33 +350,21 @@ static void deadline_exit_queue(elevator_t *e)
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BUG_ON(!list_empty(&dd->fifo_list[READ]));
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BUG_ON(!list_empty(&dd->fifo_list[WRITE]));
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mempool_destroy(dd->drq_pool);
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kfree(dd);
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}
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/*
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* initialize elevator private data (deadline_data), and alloc a drq for
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* each request on the free lists
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* initialize elevator private data (deadline_data).
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*/
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static void *deadline_init_queue(request_queue_t *q, elevator_t *e)
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{
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struct deadline_data *dd;
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if (!drq_pool)
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return NULL;
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dd = kmalloc_node(sizeof(*dd), GFP_KERNEL, q->node);
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if (!dd)
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return NULL;
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memset(dd, 0, sizeof(*dd));
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dd->drq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab,
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mempool_free_slab, drq_pool, q->node);
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if (!dd->drq_pool) {
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kfree(dd);
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return NULL;
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}
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INIT_LIST_HEAD(&dd->fifo_list[READ]);
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INIT_LIST_HEAD(&dd->fifo_list[WRITE]);
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dd->sort_list[READ] = RB_ROOT;
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@ -422,36 +377,6 @@ static void *deadline_init_queue(request_queue_t *q, elevator_t *e)
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return dd;
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}
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static void deadline_put_request(request_queue_t *q, struct request *rq)
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{
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struct deadline_data *dd = q->elevator->elevator_data;
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struct deadline_rq *drq = RQ_DATA(rq);
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mempool_free(drq, dd->drq_pool);
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rq->elevator_private = NULL;
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}
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static int
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deadline_set_request(request_queue_t *q, struct request *rq, struct bio *bio,
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gfp_t gfp_mask)
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{
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struct deadline_data *dd = q->elevator->elevator_data;
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struct deadline_rq *drq;
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drq = mempool_alloc(dd->drq_pool, gfp_mask);
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if (drq) {
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memset(drq, 0, sizeof(*drq));
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drq->request = rq;
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INIT_LIST_HEAD(&drq->fifo);
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rq->elevator_private = drq;
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return 0;
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}
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return 1;
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}
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/*
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* sysfs parts below
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*/
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@ -533,8 +458,6 @@ static struct elevator_type iosched_deadline = {
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.elevator_queue_empty_fn = deadline_queue_empty,
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.elevator_former_req_fn = elv_rb_former_request,
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.elevator_latter_req_fn = elv_rb_latter_request,
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.elevator_set_req_fn = deadline_set_request,
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.elevator_put_req_fn = deadline_put_request,
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.elevator_init_fn = deadline_init_queue,
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.elevator_exit_fn = deadline_exit_queue,
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},
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@ -546,24 +469,11 @@ static struct elevator_type iosched_deadline = {
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static int __init deadline_init(void)
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{
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int ret;
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drq_pool = kmem_cache_create("deadline_drq", sizeof(struct deadline_rq),
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0, 0, NULL, NULL);
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if (!drq_pool)
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return -ENOMEM;
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ret = elv_register(&iosched_deadline);
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if (ret)
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kmem_cache_destroy(drq_pool);
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return ret;
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return elv_register(&iosched_deadline);
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}
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static void __exit deadline_exit(void)
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{
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kmem_cache_destroy(drq_pool);
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elv_unregister(&iosched_deadline);
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}
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