diff options
| -rw-r--r-- | block/cfq-iosched.c | 81 |
1 files changed, 18 insertions, 63 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 28236f2..9d6f041 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -70,7 +70,6 @@ struct cfq_data { * rr list of queues with requests and the count of them */ struct list_head rr_list[CFQ_PRIO_LISTS]; - struct list_head busy_rr; struct list_head cur_rr; struct list_head idle_rr; 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, int preempted) { - struct list_head *list, *n; - struct cfq_queue *__cfqq; - int add_tail = 0; - - /* - * 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; + if (!cfq_cfqq_sync(cfqq)) + list_add_tail(&cfqq->cfq_list, &cfqd->rr_list[cfqq->ioprio]); + else { + struct list_head *n = &cfqd->rr_list[cfqq->ioprio]; - n = n->next; - } - list_add(&cfqq->cfq_list, n); - } else { /* * 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 - * service before, and we don't cross an async queue because - * it gets added to the end on expire. + * queue. we don't cross a new queue because it hasn't + * been service before, and we don't cross an async + * queue because it gets added to the end on expire. */ - n = list; - while ((n = n->prev) != list) { + while ((n = n->prev) != &cfqd->rr_list[cfqq->ioprio]) { struct cfq_queue *__c = list_entry_cfqq(n); 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_fifo_expire(cfqq); cfq_mark_cfqq_slice_new(cfqq); + cfq_clear_cfqq_queue_new(cfqq); 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_wait_request(cfqq); - cfq_clear_cfqq_queue_new(cfqq); /* * 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) { 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) { if (!__cfqq->next_rq || !cfq_cfqq_sync(__cfqq)) continue; dist = cfq_dist_from_last(cfqd, __cfqq->next_rq); + if (first == -1) + first = dist; if (dist < best) { best = dist; 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); return cfqq; @@ -878,12 +840,6 @@ static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd) * are spliced */ 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)) { /* * 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 */ - if (cfq_close_cooperator(cfqd, cfqq)) + if (cfq_close_cooperator(cfqd, cfqq) && + (sample_valid(cic->ttime_samples) && cic->ttime_mean > 2)) return; 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++) 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->idle_rr); @@ -2174,7 +2130,6 @@ static void *cfq_init_queue(request_queue_t *q) for (i = 0; i < CFQ_PRIO_LISTS; i++) INIT_LIST_HEAD(&cfqd->rr_list[i]); - INIT_LIST_HEAD(&cfqd->busy_rr); INIT_LIST_HEAD(&cfqd->cur_rr); INIT_LIST_HEAD(&cfqd->idle_rr); INIT_LIST_HEAD(&cfqd->cic_list); |
