===== drivers/block/cfq-iosched.c 1.16 vs edited ===== --- 1.16/drivers/block/cfq-iosched.c 2004-12-07 10:00:14 +01:00 +++ edited/drivers/block/cfq-iosched.c 2004-12-08 14:22:46 +01:00 @@ -22,21 +22,24 @@ #include #include -static unsigned long max_elapsed_crq; -static unsigned long max_elapsed_dispatch; - /* * tunables */ static int cfq_quantum = 4; /* max queue in one round of service */ static int cfq_queued = 8; /* minimum rq allocate limit per-queue*/ -static int cfq_service = HZ; /* period over which service is avg */ static int cfq_fifo_expire_r = HZ / 2; /* fifo timeout for sync requests */ static int cfq_fifo_expire_w = 5 * HZ; /* fifo timeout for async requests */ static int cfq_fifo_rate = HZ / 8; /* fifo expiry rate */ static int cfq_back_max = 16 * 1024; /* maximum backwards seek, in KiB */ static int cfq_back_penalty = 2; /* penalty of a backwards seek */ +static int cfq_slice_sync = HZ / 10; +static int cfq_slice_async = HZ / 25; +static int cfq_slice_async_rq = 16; +static int cfq_slice_idle = HZ / 249; + +static int cfq_max_depth = 4; + /* * for the hash of cfqq inside the cfqd */ @@ -55,6 +58,7 @@ #define list_entry_hash(ptr) hlist_entry((ptr), struct cfq_rq, hash) #define list_entry_cfqq(ptr) list_entry((ptr), struct cfq_queue, cfq_list) +#define list_entry_fifo(ptr) list_entry((ptr), struct request, queuelist) #define RQ_DATA(rq) (rq)->elevator_private @@ -76,22 +80,18 @@ #define rq_rb_key(rq) (rq)->sector /* - * threshold for switching off non-tag accounting - */ -#define CFQ_MAX_TAG (4) - -/* * sort key types and names */ enum { CFQ_KEY_PGID, CFQ_KEY_TGID, + CFQ_KEY_PID, CFQ_KEY_UID, CFQ_KEY_GID, CFQ_KEY_LAST, }; -static char *cfq_key_types[] = { "pgid", "tgid", "uid", "gid", NULL }; +static char *cfq_key_types[] = { "pgid", "tgid", "pid", "uid", "gid", NULL }; /* * spare queue @@ -103,6 +103,8 @@ static kmem_cache_t *cfq_ioc_pool; struct cfq_data { + atomic_t ref; + struct list_head rr_list; struct list_head empty_list; @@ -114,8 +116,6 @@ unsigned int max_queued; - atomic_t ref; - int key_type; mempool_t *crq_pool; @@ -127,6 +127,14 @@ int rq_in_driver; /* + * schedule slice state info + */ + struct timer_list timer; + struct work_struct unplug_work; + struct cfq_queue *active_queue; + unsigned int dispatch_slice; + + /* * tunables, see top of file */ unsigned int cfq_quantum; @@ -137,8 +145,10 @@ unsigned int cfq_back_penalty; unsigned int cfq_back_max; unsigned int find_best_crq; - - unsigned int cfq_tagged; + unsigned int cfq_slice[2]; + unsigned int cfq_slice_async_rq; + unsigned int cfq_slice_idle; + unsigned int cfq_max_depth; }; struct cfq_queue { @@ -150,8 +160,6 @@ struct hlist_node cfq_hash; /* hash key */ unsigned long key; - /* whether queue is on rr (or empty) list */ - int on_rr; /* on either rr or empty list of cfqd */ struct list_head cfq_list; /* sorted list of pending requests */ @@ -169,15 +177,19 @@ int key_type; - unsigned long service_start; - unsigned long service_used; - - unsigned int max_rate; + unsigned long slice_start; + unsigned long slice_end; + unsigned long service_last; /* number of requests that have been handed to the driver */ int in_flight; - /* number of currently allocated requests */ - int alloc_limit[2]; + + /* whether queue is on rr (or empty) list */ + unsigned int on_rr : 1; + /* idle slice, waiting for new request submission */ + unsigned int wait_request : 1; + /* idle slice, request added, now waiting to dispatch it */ + unsigned int must_dispatch : 1; }; struct cfq_rq { @@ -195,7 +207,6 @@ unsigned int in_flight : 1; unsigned int accounted : 1; unsigned int is_sync : 1; - unsigned int is_write : 1; }; static struct cfq_queue *cfq_find_cfq_hash(struct cfq_data *, unsigned long); @@ -219,6 +230,8 @@ default: case CFQ_KEY_TGID: return tsk->tgid; + case CFQ_KEY_PID: + return tsk->pid; case CFQ_KEY_UID: return tsk->uid; case CFQ_KEY_GID: @@ -406,67 +419,22 @@ cfqq->next_crq = cfq_find_next_crq(cfqq->cfqd, cfqq, crq); } -static int cfq_check_sort_rr_list(struct cfq_queue *cfqq) -{ - struct list_head *head = &cfqq->cfqd->rr_list; - struct list_head *next, *prev; - - /* - * list might still be ordered - */ - next = cfqq->cfq_list.next; - if (next != head) { - struct cfq_queue *cnext = list_entry_cfqq(next); - - if (cfqq->service_used > cnext->service_used) - return 1; - } - - prev = cfqq->cfq_list.prev; - if (prev != head) { - struct cfq_queue *cprev = list_entry_cfqq(prev); - - if (cfqq->service_used < cprev->service_used) - return 1; - } - - return 0; -} - -static void cfq_sort_rr_list(struct cfq_queue *cfqq, int new_queue) +static void cfq_resort_rr_list(struct cfq_queue *cfqq) { struct list_head *entry = &cfqq->cfqd->rr_list; - if (!cfqq->on_rr) - return; - if (!new_queue && !cfq_check_sort_rr_list(cfqq)) - return; - list_del(&cfqq->cfq_list); /* - * sort by our mean service_used, sub-sort by in-flight requests + * sort by when queue was last serviced */ while ((entry = entry->prev) != &cfqq->cfqd->rr_list) { struct cfq_queue *__cfqq = list_entry_cfqq(entry); - if (cfqq->service_used > __cfqq->service_used) + if (!__cfqq->service_last) + break; + if (time_before(__cfqq->service_last, cfqq->service_last)) break; - else if (cfqq->service_used == __cfqq->service_used) { - struct list_head *prv; - - while ((prv = entry->prev) != &cfqq->cfqd->rr_list) { - __cfqq = list_entry_cfqq(prv); - - WARN_ON(__cfqq->service_used > cfqq->service_used); - if (cfqq->service_used != __cfqq->service_used) - break; - if (cfqq->in_flight > __cfqq->in_flight) - break; - - entry = prv; - } - } } list_add(&cfqq->cfq_list, entry); @@ -479,16 +447,12 @@ static inline void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) { - /* - * it's currently on the empty list - */ - cfqq->on_rr = 1; - cfqd->busy_queues++; + BUG_ON(cfqq->on_rr); - if (time_after(jiffies, cfqq->service_start + cfq_service)) - cfqq->service_used >>= 3; + cfqd->busy_queues++; + cfqq->on_rr = 1; - cfq_sort_rr_list(cfqq, 1); + cfq_resort_rr_list(cfqq); } static inline void @@ -512,10 +476,10 @@ struct cfq_data *cfqd = cfqq->cfqd; BUG_ON(!cfqq->queued[crq->is_sync]); + cfqq->queued[crq->is_sync]--; cfq_update_next_crq(crq); - cfqq->queued[crq->is_sync]--; rb_erase(&crq->rb_node, &cfqq->sort_list); RB_CLEAR_COLOR(&crq->rb_node); @@ -619,17 +583,13 @@ { struct cfq_rq *crq = RQ_DATA(rq); - if (crq) { + if (crq && crq->accounted) { struct cfq_queue *cfqq = crq->cfq_queue; - if (cfqq->cfqd->cfq_tagged) { - cfqq->service_used--; - cfq_sort_rr_list(cfqq, 0); - } - crq->accounted = 0; cfqq->cfqd->rq_in_driver--; } + list_add(&rq->queuelist, &q->queue_head); } @@ -640,9 +600,8 @@ if (crq) { cfq_remove_merge_hints(q, crq); list_del_init(&rq->queuelist); + cfq_del_crq_rb(crq); - if (crq->cfq_queue) - cfq_del_crq_rb(crq); } } @@ -723,6 +682,122 @@ cfq_remove_request(q, next); } +static inline void cfq_set_active_queue(struct cfq_data *cfqd) +{ + struct cfq_queue *cfqq = NULL; + + if (!list_empty(&cfqd->rr_list)) { + cfqq = list_entry_cfqq(cfqd->rr_list.next); + + cfqq->slice_start = jiffies; + cfqq->slice_end = 0; + cfqq->wait_request = 0; + } + + cfqd->active_queue = cfqq; +} + +/* + * current cfqq expired its slice (or was too idle), select new one + */ +static inline void cfq_slice_expired(struct cfq_data *cfqd) +{ + struct cfq_queue *cfqq = cfqd->active_queue; + + if (cfqq) { + if (cfqq->wait_request) + del_timer(&cfqd->timer); + + cfqq->service_last = jiffies; + cfqq->must_dispatch = 0; + cfqq->wait_request = 0; + + if (cfqq->on_rr) + cfq_resort_rr_list(cfqq); + + cfqd->active_queue = NULL; + } + + cfqd->dispatch_slice = 0; +} + +static int cfq_arm_slice_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq, + struct cfq_io_context *cic) +{ + WARN_ON(!RB_EMPTY(&cfqq->sort_list)); + + cfqq->wait_request = 1; + + if (!cfqd->cfq_slice_idle) + return 0; + + + /* + * don't arm a slice timer if we don't expect the task to run + * after the slice has ended + */ + if (cic) { + unsigned long sched_time; + + if (!cic->ioc->task) + return 0; + + sched_time = task_will_schedule_at(cic->ioc->task); + if (sched_time && time_after(sched_time, cfqq->slice_end)) + return 0; + } + + if (!timer_pending(&cfqd->timer)) { + unsigned long now = jiffies, slice_left; + + slice_left = cfqq->slice_end - now - 1; + cfqd->timer.expires = now + min(cfqd->cfq_slice_idle, (unsigned int)slice_left); + add_timer(&cfqd->timer); + } + + return 1; +} + +/* + * get next queue for service + */ +static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd) +{ + struct cfq_queue *cfqq = cfqd->active_queue; + unsigned long now = jiffies; + + cfqq = cfqd->active_queue; + if (!cfqq) + goto new_queue; + + if (cfqq->must_dispatch) + goto must_queue; + + /* + * slice has expired + */ + if (time_after(jiffies, cfqq->slice_end)) + goto new_queue; + + /* + * if queue has requests, dispatch one. if not, check if + * enough slice is left to wait for one + */ +must_queue: + if (!RB_EMPTY(&cfqq->sort_list)) + goto keep_queue; + else if (time_before(now, cfqq->slice_end)) { + if (cfq_arm_slice_timer(cfqd, cfqq, NULL)) + return NULL; + } + +new_queue: + cfq_slice_expired(cfqd); + cfq_set_active_queue(cfqd); +keep_queue: + return cfqd->active_queue; +} + /* * we dispatch cfqd->cfq_quantum requests in total from the rr_list queues, * this function sector sorts the selected request to minimize seeks. we start @@ -741,26 +816,25 @@ list_del(&crq->request->queuelist); last = cfqd->last_sector; - while ((entry = entry->prev) != head) { - __rq = list_entry_rq(entry); - - if (blk_barrier_rq(crq->request)) + list_for_each_entry_reverse(__rq, head, queuelist) { + if (blk_barrier_rq(__rq)) break; - if (!blk_fs_request(crq->request)) + if (!blk_fs_request(__rq)) break; - if (crq->request->sector > __rq->sector) + if (__rq->sector <= crq->request->sector) break; if (__rq->sector > last && crq->request->sector < last) { last = crq->request->sector; break; } + entry = &__rq->queuelist; } cfqd->last_sector = last; crq->in_flight = 1; cfqq->in_flight++; - list_add(&crq->request->queuelist, entry); + list_add_tail(&crq->request->queuelist, entry); } /* @@ -777,97 +851,103 @@ if (time_before(now, cfqq->last_fifo_expire + cfqd->cfq_fifo_batch_expire)) return NULL; - crq = RQ_DATA(list_entry(cfqq->fifo[0].next, struct request, queuelist)); - if (reads && time_after(now, crq->queue_start + cfqd->cfq_fifo_expire_r)) { - cfqq->last_fifo_expire = now; - return crq; + if (reads) { + crq = RQ_DATA(list_entry_fifo(cfqq->fifo[READ].next)); + if (time_after(now, crq->queue_start + cfqd->cfq_fifo_expire_r)) { + cfqq->last_fifo_expire = now; + return crq; + } } - crq = RQ_DATA(list_entry(cfqq->fifo[1].next, struct request, queuelist)); - if (writes && time_after(now, crq->queue_start + cfqd->cfq_fifo_expire_w)) { - cfqq->last_fifo_expire = now; - return crq; + if (writes) { + crq = RQ_DATA(list_entry_fifo(cfqq->fifo[WRITE].next)); + if (time_after(now, crq->queue_start + cfqd->cfq_fifo_expire_w)) { + cfqq->last_fifo_expire = now; + return crq; + } } return NULL; } -/* - * dispatch a single request from given queue - */ -static inline void -cfq_dispatch_request(request_queue_t *q, struct cfq_data *cfqd, - struct cfq_queue *cfqq) +static int +__cfq_dispatch_requests(struct cfq_data *cfqd, struct cfq_queue *cfqq, + int max_dispatch) { - struct cfq_rq *crq; + int dispatched = 0, sync = 0; + + BUG_ON(RB_EMPTY(&cfqq->sort_list)); + + do { + struct cfq_rq *crq; + + /* + * follow expired path, else get first next available + */ + if ((crq = cfq_check_fifo(cfqq)) == NULL) { + if (cfqd->find_best_crq) + crq = cfqq->next_crq; + else + crq = rb_entry_crq(rb_first(&cfqq->sort_list)); + } + + cfqd->last_sector = crq->request->sector + crq->request->nr_sectors; + + /* + * finally, insert request into driver list + */ + cfq_dispatch_sort(cfqd->queue, crq); + + cfqd->dispatch_slice++; + dispatched++; + sync += crq->is_sync; + + if (RB_EMPTY(&cfqq->sort_list)) + break; + + } while (dispatched < max_dispatch); /* - * follow expired path, else get first next available + * if slice end isn't set yet, set it. if at least one request was + * sync, use the sync time slice value */ - if ((crq = cfq_check_fifo(cfqq)) == NULL) { - if (cfqd->find_best_crq) - crq = cfqq->next_crq; - else - crq = rb_entry_crq(rb_first(&cfqq->sort_list)); - } - - cfqd->last_sector = crq->request->sector + crq->request->nr_sectors; + if (!cfqq->slice_end) + cfqq->slice_end = cfqd->cfq_slice[!!sync] + jiffies; /* - * finally, insert request into driver list + * expire an async queue immediately if it has used up its slice */ - cfq_dispatch_sort(q, crq); + if (!sync && cfqd->dispatch_slice >= cfqd->cfq_slice_async_rq) + cfq_slice_expired(cfqd); + + return dispatched; } static int cfq_dispatch_requests(request_queue_t *q, int max_dispatch) { struct cfq_data *cfqd = q->elevator->elevator_data; struct cfq_queue *cfqq; - struct list_head *entry, *tmp; - int queued, busy_queues, first_round; if (list_empty(&cfqd->rr_list)) return 0; - queued = 0; - first_round = 1; -restart: - busy_queues = 0; - list_for_each_safe(entry, tmp, &cfqd->rr_list) { - cfqq = list_entry_cfqq(entry); - - BUG_ON(RB_EMPTY(&cfqq->sort_list)); - - /* - * first round of queueing, only select from queues that - * don't already have io in-flight - */ - if (first_round && cfqq->in_flight) - continue; - - cfq_dispatch_request(q, cfqd, cfqq); - - if (!RB_EMPTY(&cfqq->sort_list)) - busy_queues++; - - queued++; - } - - if ((queued < max_dispatch) && (busy_queues || first_round)) { - first_round = 0; - goto restart; + cfqq = cfq_select_queue(cfqd); + if (cfqq) { + cfqq->wait_request = 0; + cfqq->must_dispatch = 0; + del_timer(&cfqd->timer); + return __cfq_dispatch_requests(cfqd, cfqq, max_dispatch); } - return queued; + return 0; } static inline void cfq_account_dispatch(struct cfq_rq *crq) { struct cfq_queue *cfqq = crq->cfq_queue; struct cfq_data *cfqd = cfqq->cfqd; - unsigned long now, elapsed; - if (!blk_fs_request(crq->request)) + if (unlikely(!blk_fs_request(crq->request))) return; /* @@ -877,37 +957,9 @@ if (crq->accounted) return; - now = jiffies; - if (cfqq->service_start == ~0UL) - cfqq->service_start = now; - - /* - * on drives with tagged command queueing, command turn-around time - * doesn't necessarily reflect the time spent processing this very - * command inside the drive. so do the accounting differently there, - * by just sorting on the number of requests - */ - if (cfqd->cfq_tagged) { - if (time_after(now, cfqq->service_start + cfq_service)) { - cfqq->service_start = now; - cfqq->service_used /= 10; - } - - cfqq->service_used++; - cfq_sort_rr_list(cfqq, 0); - } - - elapsed = now - crq->queue_start; - if (elapsed > max_elapsed_dispatch) - max_elapsed_dispatch = elapsed; - crq->accounted = 1; - crq->service_start = now; - - if (++cfqd->rq_in_driver >= CFQ_MAX_TAG && !cfqd->cfq_tagged) { - cfqq->cfqd->cfq_tagged = 1; - printk("cfq: depth %d reached, tagging now on\n", CFQ_MAX_TAG); - } + crq->service_start = jiffies; + cfqd->rq_in_driver++; } static inline void @@ -915,27 +967,24 @@ { struct cfq_data *cfqd = cfqq->cfqd; - if (!crq->accounted) - return; - - WARN_ON(!cfqd->rq_in_driver); - cfqd->rq_in_driver--; - - if (!cfqd->cfq_tagged) { - unsigned long now = jiffies; - unsigned long duration = now - crq->service_start; - - if (time_after(now, cfqq->service_start + cfq_service)) { - cfqq->service_start = now; - cfqq->service_used >>= 3; - } + if (crq->accounted) { + WARN_ON(!cfqd->rq_in_driver); + cfqd->rq_in_driver--; + } - cfqq->service_used += duration; - cfq_sort_rr_list(cfqq, 0); + /* + * queue was preempted while this request was servicing + */ + if (cfqd->active_queue != cfqq) + return; - if (duration > max_elapsed_crq) - max_elapsed_crq = duration; - } + /* + * this is still the active queue. if we have nothing to do and no + * more pending requests in flight, wait for a new sync request if + * this request was sync itself + */ + if (RB_EMPTY(&cfqq->sort_list) && crq->is_sync && !cfqq->in_flight) + cfq_arm_slice_timer(cfqd, cfqq, crq->io_context); } static struct request *cfq_next_request(request_queue_t *q) @@ -943,6 +992,9 @@ struct cfq_data *cfqd = q->elevator->elevator_data; struct request *rq; + if (cfqd->rq_in_driver >= cfqd->cfq_max_depth) + return NULL; + if (!list_empty(&q->queue_head)) { struct cfq_rq *crq; dispatch: @@ -970,6 +1022,8 @@ */ static void cfq_put_queue(struct cfq_queue *cfqq) { + struct cfq_data *cfqd = cfqq->cfqd; + BUG_ON(!atomic_read(&cfqq->ref)); if (!atomic_dec_and_test(&cfqq->ref)) @@ -978,6 +1032,9 @@ BUG_ON(rb_first(&cfqq->sort_list)); BUG_ON(cfqq->on_rr); + if (unlikely(cfqd->active_queue == cfqq)) + cfqd->active_queue = NULL; + cfq_put_cfqd(cfqq->cfqd); /* @@ -1039,44 +1096,63 @@ spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); } +static void cfq_queue_remove(struct cfq_queue *cfqq) +{ + struct cfq_data *cfqd = cfqq->cfqd; + + /* + * don't waste time waiting for the timer to expire for + * a dead process + */ + if (cfqq == cfqd->active_queue && del_timer(&cfqd->timer)) + kblockd_schedule_work(&cfqd->unplug_work); +} + +/* + * A note on the RCU usage in CFQ: All updates on the cic list are being + * done from only one task, so no additional locking is needed. Updates are + * done in two locations: when a process sets up a new per-queue context and + * when a process exits. + */ +static void cfq_rcu_queue_put(struct rcu_head *h) +{ + struct cfq_io_context *cic = container_of(h, struct cfq_io_context,rcu); + request_queue_t *q = cic->cfqq->cfqd->queue; + unsigned long flags; + + spin_lock_irqsave(q->queue_lock, flags); + cfq_queue_remove(cic->cfqq); + cfq_put_queue(cic->cfqq); + cic->cfqq = NULL; + spin_unlock_irqrestore(q->queue_lock, flags); + + put_io_context(cic->ioc); +} + static void cfq_free_io_context(struct cfq_io_context *cic) { kmem_cache_free(cfq_ioc_pool, cic); } /* - * locking hierarchy is: io_context lock -> queue locks + * See cfq_rcu_queue_put */ static void cfq_exit_io_context(struct cfq_io_context *cic) { - struct cfq_queue *cfqq = cic->cfqq; - struct list_head *entry = &cic->list; - request_queue_t *q; - unsigned long flags; + struct list_head *entry, *nxt; + struct cfq_io_context *__cic; /* * put the reference this task is holding to the various queues */ - spin_lock_irqsave(&cic->ioc->lock, flags); - while ((entry = cic->list.next) != &cic->list) { - struct cfq_io_context *__cic; - + list_for_each_safe_rcu(entry, nxt, &cic->list) { __cic = list_entry(entry, struct cfq_io_context, list); - list_del(entry); - q = __cic->cfqq->cfqd->queue; - spin_lock(q->queue_lock); - cfq_put_queue(__cic->cfqq); - spin_unlock(q->queue_lock); + list_del_rcu(&__cic->list); + call_rcu(&__cic->rcu, cfq_rcu_queue_put); } - q = cfqq->cfqd->queue; - spin_lock(q->queue_lock); - cfq_put_queue(cfqq); - spin_unlock(q->queue_lock); - - cic->cfqq = NULL; - spin_unlock_irqrestore(&cic->ioc->lock, flags); + call_rcu(&cic->rcu, cfq_rcu_queue_put); } static struct cfq_io_context *cfq_alloc_io_context(int gfp_flags) @@ -1084,10 +1160,11 @@ struct cfq_io_context *cic = kmem_cache_alloc(cfq_ioc_pool, gfp_flags); if (cic) { - cic->dtor = cfq_free_io_context; - cic->exit = cfq_exit_io_context; INIT_LIST_HEAD(&cic->list); cic->cfqq = NULL; + INIT_RCU_HEAD(&cic->rcu); + cic->dtor = cfq_free_io_context; + cic->exit = cfq_exit_io_context; } return cic; @@ -1119,13 +1196,19 @@ if (cic == NULL) goto err; + /* + * manually increment generic io_context usage count, it + * cannot go away since we are already holding one ref to it + */ ioc->cic = cic; cic->ioc = ioc; + atomic_inc(&ioc->refcount); + cic->cfqq = __cfqq; atomic_inc(&__cfqq->ref); + atomic_inc(&cfqd->ref); } else { struct cfq_io_context *__cic; - unsigned long flags; /* * since the first cic on the list is actually the head @@ -1140,19 +1223,19 @@ * should be ok here, the list will usually not be more than * 1 or a few entries long */ - spin_lock_irqsave(&ioc->lock, flags); - list_for_each_entry(__cic, &cic->list, list) { + rcu_read_lock(); + list_for_each_entry_rcu(__cic, &cic->list, list) { /* * this process is already holding a reference to * this queue, so no need to get one more */ if (__cic->cfqq == __cfqq) { cic = __cic; - spin_unlock_irqrestore(&ioc->lock, flags); + rcu_read_unlock(); goto out; } } - spin_unlock_irqrestore(&ioc->lock, flags); + rcu_read_unlock(); /* * nope, process doesn't have a cic assoicated with this @@ -1163,12 +1246,12 @@ goto err; __cic->ioc = ioc; + atomic_inc(&ioc->refcount); + __cic->cfqq = __cfqq; atomic_inc(&__cfqq->ref); - spin_lock_irqsave(&ioc->lock, flags); - list_add(&__cic->list, &cic->list); - spin_unlock_irqrestore(&ioc->lock, flags); - + atomic_inc(&cfqd->ref); + list_add_rcu(&__cic->list, &cic->list); cic = __cic; *cfqq = __cfqq; } @@ -1205,8 +1288,11 @@ new_cfqq = kmem_cache_alloc(cfq_pool, gfp_mask); spin_lock_irq(cfqd->queue->queue_lock); goto retry; - } else - goto out; + } else { + cfqq = kmem_cache_alloc(cfq_pool, gfp_mask); + if (!cfqq) + goto out; + } memset(cfqq, 0, sizeof(*cfqq)); @@ -1222,7 +1308,7 @@ cfqq->cfqd = cfqd; atomic_inc(&cfqd->ref); cfqq->key_type = cfqd->key_type; - cfqq->service_start = ~0UL; + cfqq->service_last = 0; } if (new_cfqq) @@ -1249,14 +1335,31 @@ static void cfq_enqueue(struct cfq_data *cfqd, struct cfq_rq *crq) { - crq->is_sync = 0; - if (rq_data_dir(crq->request) == READ || current->flags & PF_SYNCWRITE) - crq->is_sync = 1; + struct cfq_queue *cfqq = crq->cfq_queue; + struct request *rq = crq->request; + + crq->is_sync = rq_data_dir(rq) == READ || current->flags & PF_SYNCWRITE; cfq_add_crq_rb(crq); crq->queue_start = jiffies; - list_add_tail(&crq->request->queuelist, &crq->cfq_queue->fifo[crq->is_sync]); + list_add_tail(&rq->queuelist, &cfqq->fifo[crq->is_sync]); + + /* + * if we are waiting for a request for this queue, let it rip + * immediately and flag that we must not expire this queue just now + */ + if (cfqq->wait_request && cfqq == cfqd->active_queue) { + request_queue_t *q = cfqd->queue; + + cfqq->must_dispatch = 1; + del_timer(&cfqd->timer); + + if (!blk_queue_plugged(q)) + q->request_fn(q); + else + __generic_unplug_device(q); + } } static void @@ -1345,32 +1448,31 @@ struct cfq_data *cfqd = q->elevator->elevator_data; struct cfq_queue *cfqq; int ret = ELV_MQUEUE_MAY; + int limit; if (current->flags & PF_MEMALLOC) return ELV_MQUEUE_MAY; cfqq = cfq_find_cfq_hash(cfqd, cfq_hash_key(cfqd, current)); - if (cfqq) { - int limit = cfqd->max_queued; - - if (cfqq->allocated[rw] < cfqd->cfq_queued) - return ELV_MQUEUE_MUST; - - if (cfqd->busy_queues) - limit = q->nr_requests / cfqd->busy_queues; + if (unlikely(!cfqq)) + return ELV_MQUEUE_MAY; - if (limit < cfqd->cfq_queued) - limit = cfqd->cfq_queued; - else if (limit > cfqd->max_queued) - limit = cfqd->max_queued; + if (cfqq->allocated[rw] < cfqd->cfq_queued) + return ELV_MQUEUE_MUST; + if (cfqq->wait_request) + return ELV_MQUEUE_MUST; + + limit = cfqd->max_queued; + if (cfqd->busy_queues) + limit = q->nr_requests / cfqd->busy_queues; + + if (limit < cfqd->cfq_queued) + limit = cfqd->cfq_queued; + else if (limit > cfqd->max_queued) + limit = cfqd->max_queued; - if (cfqq->allocated[rw] >= limit) { - if (limit > cfqq->alloc_limit[rw]) - cfqq->alloc_limit[rw] = limit; - - ret = ELV_MQUEUE_NO; - } - } + if (cfqq->allocated[rw] >= limit) + ret = ELV_MQUEUE_NO; return ret; } @@ -1378,12 +1480,13 @@ static void cfq_check_waiters(request_queue_t *q, struct cfq_queue *cfqq) { struct request_list *rl = &q->rq; - const int write = waitqueue_active(&rl->wait[WRITE]); - const int read = waitqueue_active(&rl->wait[READ]); + const int writes = waitqueue_active(&rl->wait[WRITE]); + const int reads = waitqueue_active(&rl->wait[READ]); + struct cfq_data *cfqd = q->elevator->elevator_data; - if (read && cfqq->allocated[READ] < cfqq->alloc_limit[READ]) + if (reads && cfqq->allocated[READ] < cfqd->max_queued) wake_up(&rl->wait[READ]); - if (write && cfqq->allocated[WRITE] < cfqq->alloc_limit[WRITE]) + if (writes && cfqq->allocated[WRITE] < cfqd->max_queued) wake_up(&rl->wait[WRITE]); } @@ -1397,16 +1500,17 @@ if (crq) { struct cfq_queue *cfqq = crq->cfq_queue; + const int rw = rq_data_dir(rq); BUG_ON(q->last_merge == rq); BUG_ON(!hlist_unhashed(&crq->hash)); + BUG_ON(!cfqq->allocated[rw]); + cfqq->allocated[rw]--; + if (crq->io_context) put_io_context(crq->io_context->ioc); - BUG_ON(!cfqq->allocated[crq->is_write]); - cfqq->allocated[crq->is_write]--; - mempool_free(crq, cfqd->crq_pool); rq->elevator_private = NULL; @@ -1476,9 +1580,7 @@ crq->io_context = cic; crq->service_start = crq->queue_start = 0; crq->in_flight = crq->accounted = crq->is_sync = 0; - crq->is_write = rw; rq->elevator_private = crq; - cfqq->alloc_limit[rw] = 0; return 0; } @@ -1492,6 +1594,44 @@ return 1; } +static void cfq_kick_queue(void *data) +{ + request_queue_t *q = data; + + blk_run_queue(q); +} + +static void cfq_schedule_timer(unsigned long data) +{ + struct cfq_data *cfqd = (struct cfq_data *) data; + struct cfq_queue *cfqq; + unsigned long flags; + + spin_lock_irqsave(cfqd->queue->queue_lock, flags); + + if ((cfqq = cfqd->active_queue) != NULL) { + /* + * expired + */ + if (time_after(jiffies, cfqq->slice_end)) + goto out; + + /* + * not expired and it has a request pending, let it dispatch + */ + if (!RB_EMPTY(&cfqq->sort_list)) { + cfqq->must_dispatch = 1; + goto out_cont; + } + } + +out: + cfq_slice_expired(cfqd); +out_cont: + spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); + kblockd_schedule_work(&cfqd->unplug_work); +} + static void cfq_put_cfqd(struct cfq_data *cfqd) { request_queue_t *q = cfqd->queue; @@ -1500,6 +1640,8 @@ if (!atomic_dec_and_test(&cfqd->ref)) return; + blk_sync_queue(q); + /* * kill spare queue, getting it means we have two refences to it. * drop both @@ -1508,6 +1650,11 @@ cfqq = __cfq_get_queue(cfqd, CFQ_KEY_SPARE, GFP_ATOMIC); cfq_put_queue(cfqq); cfq_put_queue(cfqq); + + /* + * restore ->nr_requests + */ + q->nr_requests = BLKDEV_MAX_RQ; spin_unlock_irq(q->queue_lock); blk_put_queue(q); @@ -1571,10 +1718,17 @@ * some requests. fairness is handled differently */ q->nr_requests = 1024; - cfqd->max_queued = q->nr_requests / 16; + cfqd->max_queued = q->nr_requests / 8; q->nr_batching = cfq_queued; - cfqd->key_type = CFQ_KEY_TGID; + cfqd->key_type = CFQ_KEY_PID; cfqd->find_best_crq = 1; + + init_timer(&cfqd->timer); + cfqd->timer.function = cfq_schedule_timer; + cfqd->timer.data = (unsigned long) cfqd; + + INIT_WORK(&cfqd->unplug_work, cfq_kick_queue, q); + atomic_set(&cfqd->ref, 1); cfqd->cfq_queued = cfq_queued; @@ -1584,6 +1738,11 @@ cfqd->cfq_fifo_batch_expire = cfq_fifo_rate; cfqd->cfq_back_max = cfq_back_max; cfqd->cfq_back_penalty = cfq_back_penalty; + cfqd->cfq_slice[0] = cfq_slice_async; + cfqd->cfq_slice[1] = cfq_slice_sync; + cfqd->cfq_slice_async_rq = cfq_slice_async_rq; + cfqd->cfq_slice_idle = cfq_slice_idle; + cfqd->cfq_max_depth = cfq_max_depth; return 0; out_spare: @@ -1630,7 +1789,6 @@ return -ENOMEM; } - /* * sysfs parts below --> */ @@ -1656,13 +1814,6 @@ } static ssize_t -cfq_clear_elapsed(struct cfq_data *cfqd, const char *page, size_t count) -{ - max_elapsed_dispatch = max_elapsed_crq = 0; - return count; -} - -static ssize_t cfq_set_key_type(struct cfq_data *cfqd, const char *page, size_t count) { spin_lock_irq(cfqd->queue->queue_lock); @@ -1670,6 +1821,8 @@ cfqd->key_type = CFQ_KEY_PGID; else if (!strncmp(page, "tgid", 4)) cfqd->key_type = CFQ_KEY_TGID; + else if (!strncmp(page, "pid", 3)) + cfqd->key_type = CFQ_KEY_PID; else if (!strncmp(page, "uid", 3)) cfqd->key_type = CFQ_KEY_UID; else if (!strncmp(page, "gid", 3)) @@ -1710,6 +1863,11 @@ SHOW_FUNCTION(cfq_find_best_show, cfqd->find_best_crq, 0); SHOW_FUNCTION(cfq_back_max_show, cfqd->cfq_back_max, 0); SHOW_FUNCTION(cfq_back_penalty_show, cfqd->cfq_back_penalty, 0); +SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1); +SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1); +SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1); +SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0); +SHOW_FUNCTION(cfq_max_depth_show, cfqd->cfq_max_depth, 0); #undef SHOW_FUNCTION #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \ @@ -1735,6 +1893,11 @@ STORE_FUNCTION(cfq_find_best_store, &cfqd->find_best_crq, 0, 1, 0); STORE_FUNCTION(cfq_back_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0); STORE_FUNCTION(cfq_back_penalty_store, &cfqd->cfq_back_penalty, 1, UINT_MAX, 0); +STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1); +STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1); +STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1); +STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1, UINT_MAX, 0); +STORE_FUNCTION(cfq_max_depth_store, &cfqd->cfq_max_depth, 2, UINT_MAX, 0); #undef STORE_FUNCTION static struct cfq_fs_entry cfq_quantum_entry = { @@ -1777,15 +1940,36 @@ .show = cfq_back_penalty_show, .store = cfq_back_penalty_store, }; -static struct cfq_fs_entry cfq_clear_elapsed_entry = { - .attr = {.name = "clear_elapsed", .mode = S_IWUSR }, - .store = cfq_clear_elapsed, +static struct cfq_fs_entry cfq_slice_sync_entry = { + .attr = {.name = "slice_sync", .mode = S_IRUGO | S_IWUSR }, + .show = cfq_slice_sync_show, + .store = cfq_slice_sync_store, +}; +static struct cfq_fs_entry cfq_slice_async_entry = { + .attr = {.name = "slice_async", .mode = S_IRUGO | S_IWUSR }, + .show = cfq_slice_async_show, + .store = cfq_slice_async_store, +}; +static struct cfq_fs_entry cfq_slice_async_rq_entry = { + .attr = {.name = "slice_async_rq", .mode = S_IRUGO | S_IWUSR }, + .show = cfq_slice_async_rq_show, + .store = cfq_slice_async_rq_store, +}; +static struct cfq_fs_entry cfq_slice_idle_entry = { + .attr = {.name = "slice_idle", .mode = S_IRUGO | S_IWUSR }, + .show = cfq_slice_idle_show, + .store = cfq_slice_idle_store, }; static struct cfq_fs_entry cfq_key_type_entry = { .attr = {.name = "key_type", .mode = S_IRUGO | S_IWUSR }, .show = cfq_read_key_type, .store = cfq_set_key_type, }; +static struct cfq_fs_entry cfq_max_depth_entry = { + .attr = {.name = "max_depth", .mode = S_IRUGO | S_IWUSR }, + .show = cfq_max_depth_show, + .store = cfq_max_depth_store, +}; static struct attribute *default_attrs[] = { &cfq_quantum_entry.attr, @@ -1797,7 +1981,11 @@ &cfq_find_best_entry.attr, &cfq_back_max_entry.attr, &cfq_back_penalty_entry.attr, - &cfq_clear_elapsed_entry.attr, + &cfq_slice_sync_entry.attr, + &cfq_slice_async_entry.attr, + &cfq_slice_async_rq_entry.attr, + &cfq_slice_idle_entry.attr, + &cfq_max_depth_entry.attr, NULL, }; @@ -1862,7 +2050,7 @@ .elevator_owner = THIS_MODULE, }; -int cfq_init(void) +static int __init cfq_init(void) { int ret; @@ -1870,17 +2058,34 @@ return -ENOMEM; ret = elv_register(&iosched_cfq); - if (!ret) { - __module_get(THIS_MODULE); - return 0; - } + if (ret) + cfq_slab_kill(); - cfq_slab_kill(); return ret; } static void __exit cfq_exit(void) { + struct task_struct *g, *p; + unsigned long flags; + + read_lock_irqsave(&tasklist_lock, flags); + + /* + * iterate each process in the system, removing our io_context + */ + do_each_thread(g, p) { + struct io_context *ioc = p->io_context; + + if (ioc && ioc->cic) { + ioc->cic->exit(ioc->cic); + cfq_free_io_context(ioc->cic); + ioc->cic = NULL; + } + } while_each_thread(g, p); + + read_unlock_irqrestore(&tasklist_lock, flags); + cfq_slab_kill(); elv_unregister(&iosched_cfq); } ===== drivers/block/ll_rw_blk.c 1.281 vs edited ===== --- 1.281/drivers/block/ll_rw_blk.c 2004-12-01 09:13:57 +01:00 +++ edited/drivers/block/ll_rw_blk.c 2004-12-08 14:22:46 +01:00 @@ -1257,11 +1257,7 @@ if (!blk_remove_plug(q)) return; - /* - * was plugged, fire request_fn if queue has stuff to do - */ - if (elv_next_request(q)) - q->request_fn(q); + q->request_fn(q); } EXPORT_SYMBOL(__generic_unplug_device); @@ -2152,7 +2148,6 @@ return; req->rq_status = RQ_INACTIVE; - req->q = NULL; req->rl = NULL; /* @@ -2502,6 +2497,7 @@ { struct request_list *rl = &q->rq; struct request *rq; + int requeued = 0; spin_lock_irq(q->queue_lock); clear_bit(QUEUE_FLAG_DRAIN, &q->queue_flags); @@ -2510,9 +2506,13 @@ rq = list_entry_rq(q->drain_list.next); list_del_init(&rq->queuelist); - __elv_add_request(q, rq, ELEVATOR_INSERT_BACK, 1); + elv_requeue_request(q, rq); + requeued++; } + if (requeued) + q->request_fn(q); + spin_unlock_irq(q->queue_lock); wake_up(&rl->wait[0]); @@ -3069,6 +3069,7 @@ local_irq_save(flags); ioc = current->io_context; current->io_context = NULL; + ioc->task = NULL; local_irq_restore(flags); if (ioc->aic && ioc->aic->exit) @@ -3103,12 +3104,11 @@ ret = kmem_cache_alloc(iocontext_cachep, gfp_flags); if (ret) { atomic_set(&ret->refcount, 1); - ret->pid = tsk->pid; + ret->task = current; ret->last_waited = jiffies; /* doesn't matter... */ ret->nr_batch_requests = 0; /* because this is 0 */ ret->aic = NULL; ret->cic = NULL; - spin_lock_init(&ret->lock); local_irq_save(flags); ===== include/linux/blkdev.h 1.157 vs edited ===== --- 1.157/include/linux/blkdev.h 2004-11-11 09:39:16 +01:00 +++ edited/include/linux/blkdev.h 2004-12-08 14:22:46 +01:00 @@ -54,16 +54,17 @@ struct cfq_queue; struct cfq_io_context { - void (*dtor)(struct cfq_io_context *); - void (*exit)(struct cfq_io_context *); - - struct io_context *ioc; - /* * circular list of cfq_io_contexts belonging to a process io context */ struct list_head list; struct cfq_queue *cfqq; + + struct rcu_head rcu; + struct io_context *ioc; + + void (*dtor)(struct cfq_io_context *); + void (*exit)(struct cfq_io_context *); }; /* @@ -73,15 +74,13 @@ */ struct io_context { atomic_t refcount; - pid_t pid; + struct task_struct *task; /* * For request batching */ unsigned long last_waited; /* Time last woken after wait for request */ int nr_batch_requests; /* Number of requests left in the batch */ - - spinlock_t lock; struct as_io_context *aic; struct cfq_io_context *cic; ===== include/linux/sched.h 1.271 vs edited ===== --- 1.271/include/linux/sched.h 2004-12-03 08:31:57 +01:00 +++ edited/include/linux/sched.h 2004-12-08 14:22:46 +01:00 @@ -740,6 +740,7 @@ extern int task_nice(const task_t *p); extern int task_curr(const task_t *p); extern int idle_cpu(int cpu); +extern unsigned long task_will_schedule_at(const task_t *p); void yield(void); ===== kernel/sched.c 1.381 vs edited ===== --- 1.381/kernel/sched.c 2004-12-07 10:00:13 +01:00 +++ edited/kernel/sched.c 2004-12-08 14:22:46 +01:00 @@ -813,6 +813,41 @@ return cpu_curr(task_cpu(p)) == p; } +/** + * task_will_schedule_at - in how many ticks will the task run, most likely + * @p: the task in question + */ +unsigned long task_will_schedule_at(const task_t *p) +{ + /* + * Task is executing right now + */ + if (task_curr(p)) + return 0; + + /* + * Task is not executing but on a runqueue - try to guess + * how much time it will take for it to run again, but using + * the current task's remaining ticks. This is not accurate, + * but a good guess. (We use the min() to avoid the small race + * that is due to us dereferencing the current task without + * locking) + */ + if (p->array) + return min(cpu_curr(task_cpu(p))->time_slice, + (unsigned int)MAX_SLEEP_AVG); + + /* + * for blocked tasks, return half of the average sleep time. + * (because this is the average sleep-time we'll see if we + * sample the period randomly.) + */ + return NS_TO_JIFFIES(p->sleep_avg) / 2; +} + +EXPORT_SYMBOL_GPL(task_will_schedule_at); + + #ifdef CONFIG_SMP enum request_type { REQ_MOVE_TASK,