diff options
| -rw-r--r-- | block/cfq-iosched.c | 381 |
1 files changed, 261 insertions, 120 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index bfb3967..28236f2 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -56,13 +56,7 @@ static struct completion *ioc_gone; #define ASYNC (0) #define SYNC (1) -#define cfq_cfqq_dispatched(cfqq) \ - ((cfqq)->on_dispatch[ASYNC] + (cfqq)->on_dispatch[SYNC]) - -#define cfq_cfqq_class_sync(cfqq) ((cfqq)->key != CFQ_KEY_ASYNC) - -#define cfq_cfqq_sync(cfqq) \ - (cfq_cfqq_class_sync(cfqq) || (cfqq)->on_dispatch[SYNC]) +#define cfq_cfqq_sync(cfqq) ((cfqq)->key != CFQ_KEY_ASYNC) #define sample_valid(samples) ((samples) > 80) @@ -79,6 +73,7 @@ struct cfq_data { struct list_head busy_rr; struct list_head cur_rr; struct list_head idle_rr; + unsigned long cur_rr_tick; unsigned int busy_queues; /* @@ -98,11 +93,12 @@ struct cfq_data { struct cfq_queue *active_queue; struct cfq_io_context *active_cic; int cur_prio, cur_end_prio; + unsigned long prio_time; unsigned int dispatch_slice; struct timer_list idle_class_timer; - sector_t last_sector; + sector_t last_position; unsigned long last_end_request; /* @@ -117,6 +113,9 @@ struct cfq_data { unsigned int cfq_slice_idle; struct list_head cic_list; + + sector_t new_seek_mean; + u64 new_seek_total; }; /* @@ -133,6 +132,8 @@ struct cfq_queue { unsigned int key; /* member of the rr/busy/cur/idle cfqd list */ struct list_head cfq_list; + /* in what tick we were last serviced */ + unsigned long rr_tick; /* sorted list of pending requests */ struct rb_root sort_list; /* if fifo isn't expired, next request to serve */ @@ -148,10 +149,11 @@ struct cfq_queue { unsigned long slice_end; unsigned long service_last; + unsigned long slice_start; long slice_resid; - /* number of requests that are on the dispatch list */ - int on_dispatch[2]; + /* number of requests that are on the dispatch list or inside driver */ + int dispatched; /* io prio of this group */ unsigned short ioprio, org_ioprio; @@ -159,6 +161,8 @@ struct cfq_queue { /* various state flags, see below */ unsigned int flags; + + sector_t last_request_pos; }; enum cfqq_state_flags { @@ -259,6 +263,8 @@ cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) * easily introduce oscillations. */ cfqq->slice_resid = 0; + + cfqq->slice_start = jiffies; } /* @@ -307,7 +313,7 @@ cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2) s1 = rq1->sector; s2 = rq2->sector; - last = cfqd->last_sector; + last = cfqd->last_position; /* * by definition, 1KiB is 2 sectors @@ -398,39 +404,42 @@ cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq, return cfq_choose_req(cfqd, next, prev); } -static void cfq_resort_rr_list(struct cfq_queue *cfqq, int preempted) +/* + * This function finds out where to insert a BE queue in the service hierarchy + */ +static void cfq_resort_be_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq, + int preempted) { - struct cfq_data *cfqd = cfqq->cfqd; struct list_head *list, *n; struct cfq_queue *__cfqq; + int add_tail = 0; /* - * Resorting requires the cfqq to be on the RR list already. + * 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 (!cfq_cfqq_on_rr(cfqq)) - return; - - list_del(&cfqq->cfq_list); - - if (cfq_class_rt(cfqq)) + 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; - else if (cfq_class_idle(cfqq)) - list = &cfqd->idle_rr; - else { + add_tail = 1; + } else + list = &cfqd->rr_list[cfqq->ioprio]; + + if (!cfq_cfqq_sync(cfqq) || add_tail) { /* - * 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 + * 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. */ - if (cfq_cfqq_dispatched(cfqq)) - list = &cfqd->busy_rr; - else - list = &cfqd->rr_list[cfqq->ioprio]; - } - - if (preempted || cfq_cfqq_queue_new(cfqq)) { + 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 @@ -444,14 +453,7 @@ static void cfq_resort_rr_list(struct cfq_queue *cfqq, int preempted) n = n->next; } - list_add_tail(&cfqq->cfq_list, n); - } else if (!cfq_cfqq_class_sync(cfqq)) { - /* - * 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); + list_add(&cfqq->cfq_list, n); } else { /* * sort by last service, but don't cross a new or async @@ -461,17 +463,54 @@ static void cfq_resort_rr_list(struct cfq_queue *cfqq, int preempted) */ n = list; while ((n = n->prev) != list) { - struct cfq_queue *__cfqq = list_entry_cfqq(n); + struct cfq_queue *__c = list_entry_cfqq(n); - if (!cfq_cfqq_class_sync(cfqq) || !__cfqq->service_last) + if (!cfq_cfqq_sync(__c) || !__c->service_last) break; - if (time_before(__cfqq->service_last, cfqq->service_last)) + if (time_before(__c->service_last, cfqq->service_last)) break; } list_add(&cfqq->cfq_list, n); } } +static void cfq_resort_rr_list(struct cfq_queue *cfqq, int preempted) +{ + struct cfq_data *cfqd = cfqq->cfqd; + struct list_head *n; + + /* + * Resorting requires the cfqq to be on the RR list already. + */ + if (!cfq_cfqq_on_rr(cfqq)) + return; + + list_del(&cfqq->cfq_list); + + if (cfq_class_rt(cfqq)) { + /* + * At to the front of the current list, but behind other + * RT queues. + */ + n = &cfqd->cur_rr; + while (n->next != &cfqd->cur_rr) + if (!cfq_class_rt(cfqq)) + break; + + list_add(&cfqq->cfq_list, n); + } else if (cfq_class_idle(cfqq)) { + /* + * IDLE goes to the tail of the idle list + */ + list_add_tail(&cfqq->cfq_list, &cfqd->idle_rr); + } else { + /* + * So we get here, ergo the queue is a regular best-effort queue + */ + cfq_resort_be_queue(cfqd, cfqq, preempted); + } +} + /* * add to busy list of queues for service, trying to be fair in ordering * the pending list according to last request service @@ -579,6 +618,8 @@ static void cfq_activate_request(request_queue_t *q, struct request *rq) */ if (!cfqd->hw_tag && cfqd->rq_in_driver > 4) cfqd->hw_tag = 1; + + cfqd->last_position = rq->hard_sector + rq->hard_nr_sectors; } static void cfq_deactivate_request(request_queue_t *q, struct request *rq) @@ -684,6 +725,7 @@ __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); + cfqq->rr_tick = cfqd->cur_rr_tick; } cfqd->active_queue = cfqq; @@ -786,10 +828,46 @@ static int cfq_get_next_prio_level(struct cfq_data *cfqd) cfqd->cur_end_prio = 0; } + cfqd->cur_rr_tick++; + cfqd->prio_time = jiffies; return prio; } -static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd) +static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd, + struct request *rq) +{ + if (rq->sector >= cfqd->last_position) + return rq->sector - cfqd->last_position; + else + return cfqd->last_position - rq->sector; +} + +static struct cfq_queue *cfq_get_best_queue(struct cfq_data *cfqd) +{ + struct cfq_queue *cfqq = NULL, *__cfqq; + sector_t best = -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 (dist < best) { + best = dist; + cfqq = __cfqq; + } + } + + /* + * Only async queue(s) available, grab first entry + */ + if (!cfqq) + cfqq = list_entry_cfqq(cfqd->cur_rr.next); + + return cfqq; +} + +static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd) { struct cfq_queue *cfqq = NULL; @@ -799,7 +877,7 @@ static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd) * empty, get next prio level and grab first entry then if any * are spliced */ - cfqq = list_entry_cfqq(cfqd->cur_rr.next); + 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 @@ -820,49 +898,128 @@ static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd) mod_timer(&cfqd->idle_class_timer, end); } + return cfqq; +} + +static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd) +{ + struct cfq_queue *cfqq; + + do { + long prio; + + cfqq = cfq_get_next_queue(cfqd); + if (!cfqq) + break; + + prio = cfq_prio_to_slice(cfqd, cfqq); + if (cfqq->slice_resid > -prio) + break; + + cfqq->slice_resid += prio; + list_del_init(&cfqq->cfq_list); + list_add_tail(&cfqq->cfq_list, &cfqd->rr_list[cfqq->ioprio]); + cfqq = NULL; + } while (1); + __cfq_set_active_queue(cfqd, cfqq); return cfqq; } -#define CIC_SEEKY(cic) ((cic)->seek_mean > (128 * 1024)) +static inline int cfq_rq_close(struct cfq_data *cfqd, struct request *rq) +{ + struct cfq_io_context *cic = cfqd->active_cic; + + if (!sample_valid(cic->seek_samples)) + return 0; + + return cfq_dist_from_last(cfqd, rq) <= cic->seek_mean; +} + +static struct cfq_queue *__cfq_close_cooperator(struct cfq_data *cfqd, + struct cfq_queue *cur_cfqq, + struct list_head *list) +{ + struct cfq_queue *cfqq; + + list_for_each_entry(cfqq, list, cfq_list) { + if (cfqq == cur_cfqq || !cfq_cfqq_sync(cfqq)) + continue; + + BUG_ON(!cfqq->next_rq); + + if (cfq_rq_close(cfqd, cfqq->next_rq)) + return cfqq; + } + + return NULL; +} + +static int cfq_close_cooperator(struct cfq_data *cfqd, + struct cfq_queue *cur_cfqq) +{ + struct cfq_queue *cfqq; + + if (!cfqd->busy_queues) + return 0; + + /* + * check cur_rr and same-prio rr_list for candidates + */ + cfqq = __cfq_close_cooperator(cfqd, cur_cfqq, &cfqd->cur_rr); + if (cfqq) + return 1; + + cfqq = __cfq_close_cooperator(cfqd, cur_cfqq, &cfqd->rr_list[cur_cfqq->ioprio]); + if (cfqq && (cfqq->rr_tick == cfqd->cur_rr_tick)) + cfqq = NULL; + + return cfqq != NULL; +} + +#define CIC_SEEKY(cic) ((cic)->seek_mean > (8 * 1024)) -static int cfq_arm_slice_timer(struct cfq_data *cfqd) +static void cfq_arm_slice_timer(struct cfq_data *cfqd) { struct cfq_queue *cfqq = cfqd->active_queue; struct cfq_io_context *cic; unsigned long sl; WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list)); + WARN_ON(cfq_cfqq_slice_new(cfqq)); /* * idle is disabled, either manually or by past process history */ - if (!cfqd->cfq_slice_idle) - return 0; - if (!cfq_cfqq_idle_window(cfqq)) - return 0; + if (!cfqd->cfq_slice_idle || !cfq_cfqq_idle_window(cfqq)) + return; + /* * task has exited, don't wait */ cic = cfqd->active_cic; if (!cic || !cic->ioc->task) - return 0; + return; + + /* + * See if this prio level has a good candidate + */ + if (cfq_close_cooperator(cfqd, cfqq)) + return; cfq_mark_cfqq_must_dispatch(cfqq); cfq_mark_cfqq_wait_request(cfqq); - sl = min(cfqq->slice_end - 1, (unsigned long) cfqd->cfq_slice_idle); - /* * we don't want to idle for seeks, but we do want to allow * fair distribution of slice time for a process doing back-to-back * seeks. so allow a little bit of time for him to submit a new rq */ + sl = cfqd->cfq_slice_idle; if (sample_valid(cic->seek_samples) && CIC_SEEKY(cic)) sl = min(sl, msecs_to_jiffies(2)); mod_timer(&cfqd->idle_slice_timer, jiffies + sl); - return 1; } static void cfq_dispatch_insert(request_queue_t *q, struct request *rq) @@ -870,7 +1027,7 @@ static void cfq_dispatch_insert(request_queue_t *q, struct request *rq) struct cfq_queue *cfqq = RQ_CFQQ(rq); cfq_remove_request(rq); - cfqq->on_dispatch[rq_is_sync(rq)]++; + cfqq->dispatched++; elv_dispatch_sort(q, rq); } @@ -891,13 +1048,13 @@ static inline struct request *cfq_check_fifo(struct cfq_queue *cfqq) if (list_empty(&cfqq->fifo)) return NULL; - fifo = cfq_cfqq_class_sync(cfqq); + fifo = cfq_cfqq_sync(cfqq); rq = rq_entry_fifo(cfqq->fifo.next); - if (time_after(jiffies, rq->start_time + cfqd->cfq_fifo_expire[fifo])) - return rq; + if (time_before(jiffies, rq->start_time + cfqd->cfq_fifo_expire[fifo])) + return NULL; - return NULL; + return rq; } static inline int @@ -922,23 +1079,26 @@ static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd) goto new_queue; /* - * slice has expired + * The active queue has run out of time, expire it and select new. */ - if (!cfq_cfqq_must_dispatch(cfqq) && cfq_slice_used(cfqq)) + if (cfq_slice_used(cfqq)) goto expire; /* - * if queue has requests, dispatch one. if not, check if - * enough slice is left to wait for one + * The active queue has requests and isn't expired, allow it to + * dispatch. */ if (!RB_EMPTY_ROOT(&cfqq->sort_list)) goto keep_queue; - else if (cfq_cfqq_slice_new(cfqq) || cfq_cfqq_dispatched(cfqq)) { + + /* + * No requests pending. If the active queue still has requests in + * flight or is idling for a new request, allow either of these + * conditions to happen (or time out) before selecting a new queue. + */ + if (cfqq->dispatched || timer_pending(&cfqd->idle_slice_timer)) { cfqq = NULL; goto keep_queue; - } else if (cfq_cfqq_class_sync(cfqq)) { - if (cfq_arm_slice_timer(cfqd)) - return NULL; } expire: @@ -1039,7 +1199,7 @@ static int cfq_dispatch_requests(request_queue_t *q, int force) { struct cfq_data *cfqd = q->elevator->elevator_data; - struct cfq_queue *cfqq, *prev_cfqq; + struct cfq_queue *cfqq; int dispatched; if (!cfqd->busy_queues) @@ -1049,23 +1209,19 @@ cfq_dispatch_requests(request_queue_t *q, int force) return cfq_forced_dispatch(cfqd); dispatched = 0; - prev_cfqq = NULL; while ((cfqq = cfq_select_queue(cfqd)) != NULL) { int max_dispatch; if (cfqd->busy_queues > 1) { /* - * Don't repeat dispatch from the previous queue. - */ - if (prev_cfqq == cfqq) - break; - - /* * So we have dispatched before in this round, if the * next queue has idling enabled (must be sync), don't - * allow it service until the previous have continued. + * allow it service until the previous have completed. */ - if (cfqd->rq_in_driver && cfq_cfqq_idle_window(cfqq)) + if (cfqd->rq_in_driver && cfq_cfqq_idle_window(cfqq) && + dispatched) + break; + if (cfqq->dispatched >= cfqd->cfq_quantum) break; } @@ -1078,7 +1234,6 @@ cfq_dispatch_requests(request_queue_t *q, int force) max_dispatch = 1; dispatched += __cfq_dispatch_requests(cfqd, cfqq, max_dispatch); - prev_cfqq = cfqq; } return dispatched; @@ -1520,7 +1675,8 @@ cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic) } static void -cfq_update_io_seektime(struct cfq_io_context *cic, struct request *rq) +cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_io_context *cic, + struct request *rq) { sector_t sdist; u64 total; @@ -1530,6 +1686,11 @@ cfq_update_io_seektime(struct cfq_io_context *cic, struct request *rq) else sdist = cic->last_request_pos - rq->sector; + if (!cic->seek_samples) { + cfqd->new_seek_total = (7*cic->seek_total + (u64)256*sdist) / 8; + cfqd->new_seek_mean = cfqd->new_seek_total / 256; + } + /* * Don't allow the seek distance to get too large from the * odd fragment, pagein, etc @@ -1580,13 +1741,16 @@ static int cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq, struct request *rq) { - struct cfq_queue *cfqq = cfqd->active_queue; - sector_t dist; + struct cfq_queue *cfqq; - if (cfq_class_idle(new_cfqq)) + cfqq = cfqd->active_queue; + if (!cfqq) return 0; - if (!cfqq) + if (cfq_slice_used(cfqq)) + return 1; + + if (cfq_class_idle(new_cfqq)) return 0; if (cfq_class_idle(cfqq)) @@ -1613,12 +1777,7 @@ cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq, * if this request is as-good as one we would expect from the * current cfqq, let it preempt */ - if (rq->sector > cfqd->last_sector) - dist = rq->sector - cfqd->last_sector; - else - dist = cfqd->last_sector - rq->sector; - - if (dist <= cfqd->active_cic->seek_mean) + if (cfq_rq_close(cfqd, rq)) return 1; return 0; @@ -1656,28 +1815,12 @@ cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq, if (rq_is_meta(rq)) cfqq->meta_pending++; - /* - * we never wait for an async request and we don't allow preemption - * of an async request. so just return early - */ - if (!rq_is_sync(rq)) { - /* - * sync process issued an async request, if it's waiting - * then expire it and kick rq handling. - */ - if (cic == cfqd->active_cic && - del_timer(&cfqd->idle_slice_timer)) { - cfq_slice_expired(cfqd, 0, 0); - blk_start_queueing(cfqd->queue); - } - return; - } - cfq_update_io_thinktime(cfqd, cic); - cfq_update_io_seektime(cic, rq); + cfq_update_io_seektime(cfqd, cic, rq); cfq_update_idle_window(cfqd, cfqq, cic); cic->last_request_pos = rq->sector + rq->nr_sectors; + cfqq->last_request_pos = cic->last_request_pos; if (cfqq == cfqd->active_queue) { /* @@ -1726,13 +1869,11 @@ static void cfq_completed_request(request_queue_t *q, struct request *rq) now = jiffies; WARN_ON(!cfqd->rq_in_driver); - WARN_ON(!cfqq->on_dispatch[sync]); + WARN_ON(!cfqq->dispatched); cfqd->rq_in_driver--; - cfqq->on_dispatch[sync]--; + cfqq->dispatched--; cfqq->service_last = now; - cfqd->last_sector = rq->hard_sector + rq->hard_nr_sectors; - if (!cfq_class_idle(cfqq)) cfqd->last_end_request = now; @@ -1752,11 +1893,12 @@ static void cfq_completed_request(request_queue_t *q, struct request *rq) } if (cfq_slice_used(cfqq)) cfq_slice_expired(cfqd, 0, 1); - else if (sync && RB_EMPTY_ROOT(&cfqq->sort_list)) { - if (!cfq_arm_slice_timer(cfqd)) - cfq_schedule_dispatch(cfqd); - } + else if (sync && RB_EMPTY_ROOT(&cfqq->sort_list)) + cfq_arm_slice_timer(cfqd); } + + if (!cfqd->rq_in_driver) + cfq_schedule_dispatch(cfqd); } /* @@ -2101,7 +2243,6 @@ fail: /* * sysfs parts below --> */ - static ssize_t cfq_var_show(unsigned int var, char *page) { |
