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Commit 1afba045 authored by Jens Axboe's avatar Jens Axboe Committed by Jens Axboe
Browse files

cfq-iosched: minor updates 



- Move the queue_new flag clear to when the queue is selected
- Only select the non-first queue in cfq_get_best_queue(), if there's
  a substantial difference between the best and first.
- Get rid of ->busy_rr
- Only select a close cooperator, if the current queue is known to take
  a while to "think".

Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
parent 6d048f53

block/cfq-iosched.c

+18 −63
Original line number Original line Diff line number Diff line
@@ -70,7 +70,6 @@ struct cfq_data { 
	 * rr list of queues with requests and the count of them

	 * rr list of queues with requests and the count of them

	 */

	 */

	struct list_head rr_list[CFQ_PRIO_LISTS];

	struct list_head rr_list[CFQ_PRIO_LISTS];

	struct list_head busy_rr;

	struct list_head cur_rr;

	struct list_head cur_rr;

	struct list_head idle_rr;

	struct list_head idle_rr;

	unsigned long cur_rr_tick;

	unsigned long cur_rr_tick;
@@ -410,59 +409,18 @@ cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq, 
static void cfq_resort_be_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq,

static void cfq_resort_be_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq,

				int preempted)

				int preempted)

{

{

	struct list_head *list, *n;

	if (!cfq_cfqq_sync(cfqq))

	struct cfq_queue *__cfqq;

		list_add_tail(&cfqq->cfq_list, &cfqd->rr_list[cfqq->ioprio]);

	int add_tail = 0;

	else {



		struct list_head *n = &cfqd->rr_list[cfqq->ioprio];

	/*

	 * if cfqq has requests in flight, don't allow it to be

	 * found in cfq_set_active_queue before it has finished them.

	 * this is done to increase fairness between a process that

	 * has lots of io pending vs one that only generates one

	 * sporadically or synchronously

	 */

	if (cfqq->dispatched)

		list = &cfqd->busy_rr;

	else if (cfqq->ioprio == (cfqd->cur_prio + 1) &&

		 cfq_cfqq_sync(cfqq) &&

		 (time_before(cfqd->prio_time, cfqq->service_last) ||

		  cfq_cfqq_queue_new(cfqq) || preempted)) {

		list = &cfqd->cur_rr;

		add_tail = 1;

	} else

		list = &cfqd->rr_list[cfqq->ioprio];



	if (!cfq_cfqq_sync(cfqq) || add_tail) {

		/*

		 * async queue always goes to the end. this wont be overly

		 * unfair to writes, as the sort of the sync queue wont be

		 * allowed to pass the async queue again.

		 */

		list_add_tail(&cfqq->cfq_list, list);

	} else if (preempted || cfq_cfqq_queue_new(cfqq)) {

		/*

		 * If this queue was preempted or is new (never been serviced),

		 * let it be added first for fairness but beind other new

		 * queues.

		 */

		n = list;

		while (n->next != list) {

			__cfqq = list_entry_cfqq(n->next);

			if (!cfq_cfqq_queue_new(__cfqq))

				break;





			n = n->next;

		}

		list_add(&cfqq->cfq_list, n);

	} else {

		/*

		/*

		 * sort by last service, but don't cross a new or async

		 * sort by last service, but don't cross a new or async

		 * queue. we don't cross a new queue because it hasn't been

		 * queue. we don't cross a new queue because it hasn't

		 * service before, and we don't cross an async queue because

		 * been service before, and we don't cross an async

		 * it gets added to the end on expire.

		 * queue because it gets added to the end on expire.

		 */

		 */

		n = list;

		while ((n = n->prev) != &cfqd->rr_list[cfqq->ioprio]) {

		while ((n = n->prev) != list) {

			struct cfq_queue *__c = list_entry_cfqq(n);

			struct cfq_queue *__c = list_entry_cfqq(n);





			if (!cfq_cfqq_sync(__c) || !__c->service_last)

			if (!cfq_cfqq_sync(__c) || !__c->service_last)
@@ -725,6 +683,7 @@ __cfq_set_active_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq) 
		cfq_clear_cfqq_must_alloc_slice(cfqq);

		cfq_clear_cfqq_must_alloc_slice(cfqq);

		cfq_clear_cfqq_fifo_expire(cfqq);

		cfq_clear_cfqq_fifo_expire(cfqq);

		cfq_mark_cfqq_slice_new(cfqq);

		cfq_mark_cfqq_slice_new(cfqq);

		cfq_clear_cfqq_queue_new(cfqq);

		cfqq->rr_tick = cfqd->cur_rr_tick;

		cfqq->rr_tick = cfqd->cur_rr_tick;

	}

	}
@@ -743,7 +702,6 @@ __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq, 




	cfq_clear_cfqq_must_dispatch(cfqq);

	cfq_clear_cfqq_must_dispatch(cfqq);

	cfq_clear_cfqq_wait_request(cfqq);

	cfq_clear_cfqq_wait_request(cfqq);

	cfq_clear_cfqq_queue_new(cfqq);





	/*

	/*

	 * store what was left of this slice, if the queue idled out

	 * store what was left of this slice, if the queue idled out
@@ -845,13 +803,15 @@ static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd, 
static struct cfq_queue *cfq_get_best_queue(struct cfq_data *cfqd)

static struct cfq_queue *cfq_get_best_queue(struct cfq_data *cfqd)

{

{

	struct cfq_queue *cfqq = NULL, *__cfqq;

	struct cfq_queue *cfqq = NULL, *__cfqq;

	sector_t best = -1, dist;

	sector_t best = -1, first = -1, dist;





	list_for_each_entry(__cfqq, &cfqd->cur_rr, cfq_list) {

	list_for_each_entry(__cfqq, &cfqd->cur_rr, cfq_list) {

		if (!__cfqq->next_rq || !cfq_cfqq_sync(__cfqq))

		if (!__cfqq->next_rq || !cfq_cfqq_sync(__cfqq))

			continue;

			continue;





		dist = cfq_dist_from_last(cfqd, __cfqq->next_rq);

		dist = cfq_dist_from_last(cfqd, __cfqq->next_rq);

		if (first == -1)

			first = dist;

		if (dist < best) {

		if (dist < best) {

			best = dist;

			best = dist;

			cfqq = __cfqq;

			cfqq = __cfqq;
@@ -859,9 +819,11 @@ static struct cfq_queue *cfq_get_best_queue(struct cfq_data *cfqd) 
	}

	}





	/*

	/*

	 * Only async queue(s) available, grab first entry

	 * Only async queue(s) available, grab first entry. Do the same

	 * if the difference between the first and best isn't more than

	 * twice, to obey fairness.

	 */

	 */

	if (!cfqq)

	if (!cfqq || (best && first != best && ((first / best) < 4)))

		cfqq = list_entry_cfqq(cfqd->cur_rr.next);

		cfqq = list_entry_cfqq(cfqd->cur_rr.next);





	return cfqq;

	return cfqq;
@@ -878,12 +840,6 @@ static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd) 
		 * are spliced

		 * are spliced

		 */

		 */

		cfqq = cfq_get_best_queue(cfqd);

		cfqq = cfq_get_best_queue(cfqd);

	} else if (!list_empty(&cfqd->busy_rr)) {

		/*

		 * If no new queues are available, check if the busy list has

		 * some before falling back to idle io.

		 */

		cfqq = list_entry_cfqq(cfqd->busy_rr.next);

	} else if (!list_empty(&cfqd->idle_rr)) {

	} else if (!list_empty(&cfqd->idle_rr)) {

		/*

		/*

		 * if we have idle queues and no rt or be queues had pending

		 * if we have idle queues and no rt or be queues had pending
@@ -1004,7 +960,8 @@ static void cfq_arm_slice_timer(struct cfq_data *cfqd) 
	/*

	/*

	 * See if this prio level has a good candidate

	 * See if this prio level has a good candidate

	 */

	 */

	if (cfq_close_cooperator(cfqd, cfqq))

	if (cfq_close_cooperator(cfqd, cfqq) &&

	    (sample_valid(cic->ttime_samples) && cic->ttime_mean > 2))

		return;

		return;





	cfq_mark_cfqq_must_dispatch(cfqq);

	cfq_mark_cfqq_must_dispatch(cfqq);
@@ -1184,7 +1141,6 @@ cfq_forced_dispatch(struct cfq_data *cfqd) 
	for (i = 0; i < CFQ_PRIO_LISTS; i++)

	for (i = 0; i < CFQ_PRIO_LISTS; i++)

		dispatched += cfq_forced_dispatch_cfqqs(&cfqd->rr_list[i]);

		dispatched += cfq_forced_dispatch_cfqqs(&cfqd->rr_list[i]);





	dispatched += cfq_forced_dispatch_cfqqs(&cfqd->busy_rr);

	dispatched += cfq_forced_dispatch_cfqqs(&cfqd->cur_rr);

	dispatched += cfq_forced_dispatch_cfqqs(&cfqd->cur_rr);

	dispatched += cfq_forced_dispatch_cfqqs(&cfqd->idle_rr);

	dispatched += cfq_forced_dispatch_cfqqs(&cfqd->idle_rr);
@@ -2174,7 +2130,6 @@ static void *cfq_init_queue(request_queue_t *q) 
	for (i = 0; i < CFQ_PRIO_LISTS; i++)

	for (i = 0; i < CFQ_PRIO_LISTS; i++)

		INIT_LIST_HEAD(&cfqd->rr_list[i]);

		INIT_LIST_HEAD(&cfqd->rr_list[i]);





	INIT_LIST_HEAD(&cfqd->busy_rr);

	INIT_LIST_HEAD(&cfqd->cur_rr);

	INIT_LIST_HEAD(&cfqd->cur_rr);

	INIT_LIST_HEAD(&cfqd->idle_rr);

	INIT_LIST_HEAD(&cfqd->idle_rr);

	INIT_LIST_HEAD(&cfqd->cic_list);

	INIT_LIST_HEAD(&cfqd->cic_list);