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author | Jens Axboe <jens.axboe@oracle.com> | 2009-11-03 21:12:10 +0100 |
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committer | Jens Axboe <jens.axboe@oracle.com> | 2009-11-03 21:12:10 +0100 |
commit | 150e6c67f4bf6ab51e62defc41bd19a2eefe5709 (patch) | |
tree | 586bd5450afc4f142d78017389af260e76c19f0b /block/cfq-iosched.c | |
parent | 4f570f995f68ef77aae7e5a441222f59232f2d0e (diff) | |
parent | 5869619cb5b26754574375472fe54a390edf34c7 (diff) | |
download | linux-3.10-150e6c67f4bf6ab51e62defc41bd19a2eefe5709.tar.gz linux-3.10-150e6c67f4bf6ab51e62defc41bd19a2eefe5709.tar.bz2 linux-3.10-150e6c67f4bf6ab51e62defc41bd19a2eefe5709.zip |
Merge branch 'cfq-2.6.33' into for-2.6.33
Diffstat (limited to 'block/cfq-iosched.c')
-rw-r--r-- | block/cfq-iosched.c | 373 |
1 files changed, 321 insertions, 52 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 757010d8fb7..8b5ba184cf9 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -27,6 +27,8 @@ static const int cfq_slice_sync = HZ / 10; static int cfq_slice_async = HZ / 25; static const int cfq_slice_async_rq = 2; static int cfq_slice_idle = HZ / 125; +static const int cfq_target_latency = HZ * 3/10; /* 300 ms */ +static const int cfq_hist_divisor = 4; /* * offset from end of service tree @@ -73,8 +75,9 @@ static DEFINE_SPINLOCK(ioc_gone_lock); struct cfq_rb_root { struct rb_root rb; struct rb_node *left; + unsigned count; }; -#define CFQ_RB_ROOT (struct cfq_rb_root) { RB_ROOT, NULL, } +#define CFQ_RB_ROOT (struct cfq_rb_root) { RB_ROOT, NULL, 0, } /* * Per process-grouping structure @@ -126,19 +129,48 @@ struct cfq_queue { pid_t pid; + struct cfq_rb_root *service_tree; struct cfq_queue *new_cfqq; }; /* + * First index in the service_trees. + * IDLE is handled separately, so it has negative index + */ +enum wl_prio_t { + IDLE_WORKLOAD = -1, + BE_WORKLOAD = 0, + RT_WORKLOAD = 1 +}; + +/* + * Second index in the service_trees. + */ +enum wl_type_t { + ASYNC_WORKLOAD = 0, + SYNC_NOIDLE_WORKLOAD = 1, + SYNC_WORKLOAD = 2 +}; + + +/* * Per block device queue structure */ struct cfq_data { struct request_queue *queue; /* - * rr list of queues with requests and the count of them + * rr lists of queues with requests, onle rr for each priority class. + * Counts are embedded in the cfq_rb_root + */ + struct cfq_rb_root service_trees[2][3]; + struct cfq_rb_root service_tree_idle; + /* + * The priority currently being served */ - struct cfq_rb_root service_tree; + enum wl_prio_t serving_prio; + enum wl_type_t serving_type; + unsigned long workload_expires; /* * Each priority tree is sorted by next_request position. These @@ -148,6 +180,7 @@ struct cfq_data { struct rb_root prio_trees[CFQ_PRIO_LISTS]; unsigned int busy_queues; + unsigned int busy_queues_avg[2]; int rq_in_driver[2]; int sync_flight; @@ -199,6 +232,16 @@ struct cfq_data { unsigned long last_end_sync_rq; }; +static struct cfq_rb_root *service_tree_for(enum wl_prio_t prio, + enum wl_type_t type, + struct cfq_data *cfqd) +{ + if (prio == IDLE_WORKLOAD) + return &cfqd->service_tree_idle; + + return &cfqd->service_trees[prio][type]; +} + enum cfqq_state_flags { CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */ CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */ @@ -243,6 +286,35 @@ CFQ_CFQQ_FNS(coop); #define cfq_log(cfqd, fmt, args...) \ blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args) +static inline enum wl_prio_t cfqq_prio(struct cfq_queue *cfqq) +{ + if (cfq_class_idle(cfqq)) + return IDLE_WORKLOAD; + if (cfq_class_rt(cfqq)) + return RT_WORKLOAD; + return BE_WORKLOAD; +} + + +static enum wl_type_t cfqq_type(struct cfq_queue *cfqq) +{ + if (!cfq_cfqq_sync(cfqq)) + return ASYNC_WORKLOAD; + if (!cfq_cfqq_idle_window(cfqq)) + return SYNC_NOIDLE_WORKLOAD; + return SYNC_WORKLOAD; +} + +static inline int cfq_busy_queues_wl(enum wl_prio_t wl, struct cfq_data *cfqd) +{ + if (wl == IDLE_WORKLOAD) + return cfqd->service_tree_idle.count; + + return cfqd->service_trees[wl][ASYNC_WORKLOAD].count + + cfqd->service_trees[wl][SYNC_NOIDLE_WORKLOAD].count + + cfqd->service_trees[wl][SYNC_WORKLOAD].count; +} + static void cfq_dispatch_insert(struct request_queue *, struct request *); static struct cfq_queue *cfq_get_queue(struct cfq_data *, bool, struct io_context *, gfp_t); @@ -315,10 +387,49 @@ cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio); } +/* + * get averaged number of queues of RT/BE priority. + * average is updated, with a formula that gives more weight to higher numbers, + * to quickly follows sudden increases and decrease slowly + */ + +static inline unsigned cfq_get_avg_queues(struct cfq_data *cfqd, bool rt) +{ + unsigned min_q, max_q; + unsigned mult = cfq_hist_divisor - 1; + unsigned round = cfq_hist_divisor / 2; + unsigned busy = cfq_busy_queues_wl(rt, cfqd); + + min_q = min(cfqd->busy_queues_avg[rt], busy); + max_q = max(cfqd->busy_queues_avg[rt], busy); + cfqd->busy_queues_avg[rt] = (mult * max_q + min_q + round) / + cfq_hist_divisor; + return cfqd->busy_queues_avg[rt]; +} + static inline void cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) { - cfqq->slice_end = cfq_prio_to_slice(cfqd, cfqq) + jiffies; + unsigned slice = cfq_prio_to_slice(cfqd, cfqq); + if (cfqd->cfq_latency) { + /* interested queues (we consider only the ones with the same + * priority class) */ + unsigned iq = cfq_get_avg_queues(cfqd, cfq_class_rt(cfqq)); + unsigned sync_slice = cfqd->cfq_slice[1]; + unsigned expect_latency = sync_slice * iq; + if (expect_latency > cfq_target_latency) { + unsigned base_low_slice = 2 * cfqd->cfq_slice_idle; + /* scale low_slice according to IO priority + * and sync vs async */ + unsigned low_slice = + min(slice, base_low_slice * slice / sync_slice); + /* the adapted slice value is scaled to fit all iqs + * into the target latency */ + slice = max(slice * cfq_target_latency / expect_latency, + low_slice); + } + } + cfqq->slice_end = jiffies + slice; cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies); } @@ -457,6 +568,7 @@ static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root) if (root->left == n) root->left = NULL; rb_erase_init(n, &root->rb); + --root->count; } /* @@ -497,7 +609,7 @@ static unsigned long cfq_slice_offset(struct cfq_data *cfqd, } /* - * The cfqd->service_tree holds all pending cfq_queue's that have + * The cfqd->service_trees holds all pending cfq_queue's that have * requests waiting to be processed. It is sorted in the order that * we will service the queues. */ @@ -507,11 +619,13 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq, struct rb_node **p, *parent; struct cfq_queue *__cfqq; unsigned long rb_key; + struct cfq_rb_root *service_tree; int left; + service_tree = service_tree_for(cfqq_prio(cfqq), cfqq_type(cfqq), cfqd); if (cfq_class_idle(cfqq)) { rb_key = CFQ_IDLE_DELAY; - parent = rb_last(&cfqd->service_tree.rb); + parent = rb_last(&service_tree->rb); if (parent && parent != &cfqq->rb_node) { __cfqq = rb_entry(parent, struct cfq_queue, rb_node); rb_key += __cfqq->rb_key; @@ -529,7 +643,7 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq, cfqq->slice_resid = 0; } else { rb_key = -HZ; - __cfqq = cfq_rb_first(&cfqd->service_tree); + __cfqq = cfq_rb_first(service_tree); rb_key += __cfqq ? __cfqq->rb_key : jiffies; } @@ -537,15 +651,18 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq, /* * same position, nothing more to do */ - if (rb_key == cfqq->rb_key) + if (rb_key == cfqq->rb_key && + cfqq->service_tree == service_tree) return; - cfq_rb_erase(&cfqq->rb_node, &cfqd->service_tree); + cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree); + cfqq->service_tree = NULL; } left = 1; parent = NULL; - p = &cfqd->service_tree.rb.rb_node; + cfqq->service_tree = service_tree; + p = &service_tree->rb.rb_node; while (*p) { struct rb_node **n; @@ -553,35 +670,25 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq, __cfqq = rb_entry(parent, struct cfq_queue, rb_node); /* - * sort RT queues first, we always want to give - * preference to them. IDLE queues goes to the back. - * after that, sort on the next service time. + * sort by key, that represents service time. */ - if (cfq_class_rt(cfqq) > cfq_class_rt(__cfqq)) + if (time_before(rb_key, __cfqq->rb_key)) n = &(*p)->rb_left; - else if (cfq_class_rt(cfqq) < cfq_class_rt(__cfqq)) - n = &(*p)->rb_right; - else if (cfq_class_idle(cfqq) < cfq_class_idle(__cfqq)) - n = &(*p)->rb_left; - else if (cfq_class_idle(cfqq) > cfq_class_idle(__cfqq)) - n = &(*p)->rb_right; - else if (time_before(rb_key, __cfqq->rb_key)) - n = &(*p)->rb_left; - else + else { n = &(*p)->rb_right; - - if (n == &(*p)->rb_right) left = 0; + } p = n; } if (left) - cfqd->service_tree.left = &cfqq->rb_node; + service_tree->left = &cfqq->rb_node; cfqq->rb_key = rb_key; rb_link_node(&cfqq->rb_node, parent, p); - rb_insert_color(&cfqq->rb_node, &cfqd->service_tree.rb); + rb_insert_color(&cfqq->rb_node, &service_tree->rb); + service_tree->count++; } static struct cfq_queue * @@ -683,8 +790,10 @@ static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) BUG_ON(!cfq_cfqq_on_rr(cfqq)); cfq_clear_cfqq_on_rr(cfqq); - if (!RB_EMPTY_NODE(&cfqq->rb_node)) - cfq_rb_erase(&cfqq->rb_node, &cfqd->service_tree); + if (!RB_EMPTY_NODE(&cfqq->rb_node)) { + cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree); + cfqq->service_tree = NULL; + } if (cfqq->p_root) { rb_erase(&cfqq->p_node, cfqq->p_root); cfqq->p_root = NULL; @@ -945,10 +1054,12 @@ static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out) */ static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd) { - if (RB_EMPTY_ROOT(&cfqd->service_tree.rb)) - return NULL; + struct cfq_rb_root *service_tree = + service_tree_for(cfqd->serving_prio, cfqd->serving_type, cfqd); - return cfq_rb_first(&cfqd->service_tree); + if (RB_EMPTY_ROOT(&service_tree->rb)) + return NULL; + return cfq_rb_first(service_tree); } /* @@ -1065,9 +1176,45 @@ static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd, if (CFQQ_SEEKY(cfqq)) return NULL; + /* + * Do not merge queues of different priority classes + */ + if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq)) + return NULL; + return cfqq; } +/* + * Determine whether we should enforce idle window for this queue. + */ + +static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq) +{ + enum wl_prio_t prio = cfqq_prio(cfqq); + struct cfq_rb_root *service_tree = cfqq->service_tree; + + /* We never do for idle class queues. */ + if (prio == IDLE_WORKLOAD) + return false; + + /* We do for queues that were marked with idle window flag. */ + if (cfq_cfqq_idle_window(cfqq)) + return true; + + /* + * Otherwise, we do only if they are the last ones + * in their service tree. + */ + if (!service_tree) + service_tree = service_tree_for(prio, cfqq_type(cfqq), cfqd); + + if (service_tree->count == 0) + return true; + + return (service_tree->count == 1 && cfq_rb_first(service_tree) == cfqq); +} + static void cfq_arm_slice_timer(struct cfq_data *cfqd) { struct cfq_queue *cfqq = cfqd->active_queue; @@ -1088,7 +1235,7 @@ static void cfq_arm_slice_timer(struct cfq_data *cfqd) /* * idle is disabled, either manually or by past process history */ - if (!cfqd->cfq_slice_idle || !cfq_cfqq_idle_window(cfqq)) + if (!cfqd->cfq_slice_idle || !cfq_should_idle(cfqd, cfqq)) return; /* @@ -1115,14 +1262,20 @@ static void cfq_arm_slice_timer(struct cfq_data *cfqd) cfq_mark_cfqq_wait_request(cfqq); - /* - * 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(cfqq->seek_samples) && CFQQ_SEEKY(cfqq)) + /* are we servicing noidle tree, and there are more queues? + * non-rotational or NCQ: no idle + * non-NCQ rotational : very small idle, to allow + * fair distribution of slice time for a process doing back-to-back + * seeks. + */ + if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD && + service_tree_for(cfqd->serving_prio, SYNC_NOIDLE_WORKLOAD, cfqd) + ->count > 0) { + if (blk_queue_nonrot(cfqd->queue) || cfqd->hw_tag) + return; sl = min(sl, msecs_to_jiffies(CFQ_MIN_TT)); + } mod_timer(&cfqd->idle_slice_timer, jiffies + sl); cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu", sl); @@ -1226,6 +1379,106 @@ static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq) } } +static enum wl_type_t cfq_choose_wl(struct cfq_data *cfqd, enum wl_prio_t prio, + bool prio_changed) +{ + struct cfq_queue *queue; + int i; + bool key_valid = false; + unsigned long lowest_key = 0; + enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD; + + if (prio_changed) { + /* + * When priorities switched, we prefer starting + * from SYNC_NOIDLE (first choice), or just SYNC + * over ASYNC + */ + if (service_tree_for(prio, cur_best, cfqd)->count) + return cur_best; + cur_best = SYNC_WORKLOAD; + if (service_tree_for(prio, cur_best, cfqd)->count) + return cur_best; + + return ASYNC_WORKLOAD; + } + + for (i = 0; i < 3; ++i) { + /* otherwise, select the one with lowest rb_key */ + queue = cfq_rb_first(service_tree_for(prio, i, cfqd)); + if (queue && + (!key_valid || time_before(queue->rb_key, lowest_key))) { + lowest_key = queue->rb_key; + cur_best = i; + key_valid = true; + } + } + + return cur_best; +} + +static void choose_service_tree(struct cfq_data *cfqd) +{ + enum wl_prio_t previous_prio = cfqd->serving_prio; + bool prio_changed; + unsigned slice; + unsigned count; + + /* Choose next priority. RT > BE > IDLE */ + if (cfq_busy_queues_wl(RT_WORKLOAD, cfqd)) + cfqd->serving_prio = RT_WORKLOAD; + else if (cfq_busy_queues_wl(BE_WORKLOAD, cfqd)) + cfqd->serving_prio = BE_WORKLOAD; + else { + cfqd->serving_prio = IDLE_WORKLOAD; + cfqd->workload_expires = jiffies + 1; + return; + } + + /* + * For RT and BE, we have to choose also the type + * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload + * expiration time + */ + prio_changed = (cfqd->serving_prio != previous_prio); + count = service_tree_for(cfqd->serving_prio, cfqd->serving_type, cfqd) + ->count; + + /* + * If priority didn't change, check workload expiration, + * and that we still have other queues ready + */ + if (!prio_changed && count && + !time_after(jiffies, cfqd->workload_expires)) + return; + + /* otherwise select new workload type */ + cfqd->serving_type = + cfq_choose_wl(cfqd, cfqd->serving_prio, prio_changed); + count = service_tree_for(cfqd->serving_prio, cfqd->serving_type, cfqd) + ->count; + + /* + * the workload slice is computed as a fraction of target latency + * proportional to the number of queues in that workload, over + * all the queues in the same priority class + */ + slice = cfq_target_latency * count / + max_t(unsigned, cfqd->busy_queues_avg[cfqd->serving_prio], + cfq_busy_queues_wl(cfqd->serving_prio, cfqd)); + + if (cfqd->serving_type == ASYNC_WORKLOAD) + /* async workload slice is scaled down according to + * the sync/async slice ratio. */ + slice = slice * cfqd->cfq_slice[0] / cfqd->cfq_slice[1]; + else + /* sync workload slice is at least 2 * cfq_slice_idle */ + slice = max(slice, 2 * cfqd->cfq_slice_idle); + + slice = max_t(unsigned, slice, CFQ_MIN_TT); + cfqd->workload_expires = jiffies + slice; +} + /* * Select a queue for service. If we have a current active queue, * check whether to continue servicing it, or retrieve and set a new one. @@ -1270,7 +1523,7 @@ static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd) * conditions to happen (or time out) before selecting a new queue. */ if (timer_pending(&cfqd->idle_slice_timer) || - (cfqq->dispatched && cfq_cfqq_idle_window(cfqq))) { + (cfqq->dispatched && cfq_should_idle(cfqd, cfqq))) { cfqq = NULL; goto keep_queue; } @@ -1278,6 +1531,13 @@ static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd) expire: cfq_slice_expired(cfqd, 0); new_queue: + /* + * Current queue expired. Check if we have to switch to a new + * service tree + */ + if (!new_cfqq) + choose_service_tree(cfqd); + cfqq = cfq_set_active_queue(cfqd, new_cfqq); keep_queue: return cfqq; @@ -1304,8 +1564,14 @@ static int cfq_forced_dispatch(struct cfq_data *cfqd) { struct cfq_queue *cfqq; int dispatched = 0; - - while ((cfqq = cfq_rb_first(&cfqd->service_tree)) != NULL) + int i, j; + for (i = 0; i < 2; ++i) + for (j = 0; j < 3; ++j) + while ((cfqq = cfq_rb_first(&cfqd->service_trees[i][j])) + != NULL) + dispatched += __cfq_forced_dispatch_cfqq(cfqq); + + while ((cfqq = cfq_rb_first(&cfqd->service_tree_idle)) != NULL) dispatched += __cfq_forced_dispatch_cfqq(cfqq); cfq_slice_expired(cfqd, 0); @@ -1323,7 +1589,7 @@ static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq) /* * Drain async requests before we start sync IO */ - if (cfq_cfqq_idle_window(cfqq) && cfqd->rq_in_driver[BLK_RW_ASYNC]) + if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_driver[BLK_RW_ASYNC]) return false; /* @@ -2086,13 +2352,10 @@ cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq, enable_idle = old_idle = cfq_cfqq_idle_window(cfqq); if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle || - (!cfqd->cfq_latency && cfqd->hw_tag && CFQQ_SEEKY(cfqq))) + (sample_valid(cfqq->seek_samples) && CFQQ_SEEKY(cfqq))) enable_idle = 0; else if (sample_valid(cic->ttime_samples)) { - unsigned int slice_idle = cfqd->cfq_slice_idle; - if (sample_valid(cfqq->seek_samples) && CFQQ_SEEKY(cfqq)) - slice_idle = msecs_to_jiffies(CFQ_MIN_TT); - if (cic->ttime_mean > slice_idle) + if (cic->ttime_mean > cfqd->cfq_slice_idle) enable_idle = 0; else enable_idle = 1; @@ -2130,6 +2393,10 @@ cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq, if (cfq_class_idle(cfqq)) return true; + if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD + && new_cfqq->service_tree == cfqq->service_tree) + return true; + /* * if the new request is sync, but the currently running queue is * not, let the sync request have priority. @@ -2243,10 +2510,9 @@ static void cfq_insert_request(struct request_queue *q, struct request *rq) cfq_log_cfqq(cfqd, cfqq, "insert_request"); cfq_init_prio_data(cfqq, RQ_CIC(rq)->ioc); - cfq_add_rq_rb(rq); - rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]); list_add_tail(&rq->queuelist, &cfqq->fifo); + cfq_add_rq_rb(rq); cfq_rq_enqueued(cfqd, cfqq, rq); } @@ -2645,13 +2911,16 @@ static void cfq_exit_queue(struct elevator_queue *e) static void *cfq_init_queue(struct request_queue *q) { struct cfq_data *cfqd; - int i; + int i, j; cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node); if (!cfqd) return NULL; - cfqd->service_tree = CFQ_RB_ROOT; + for (i = 0; i < 2; ++i) + for (j = 0; j < 3; ++j) + cfqd->service_trees[i][j] = CFQ_RB_ROOT; + cfqd->service_tree_idle = CFQ_RB_ROOT; /* * Not strictly needed (since RB_ROOT just clears the node and we |