diff options
Diffstat (limited to 'block/mq-deadline.c')
| -rw-r--r-- | block/mq-deadline.c | 1248 |
1 files changed, 1248 insertions, 0 deletions
diff --git a/block/mq-deadline.c b/block/mq-deadline.c new file mode 100644 index 000000000..55e26065c --- /dev/null +++ b/block/mq-deadline.c @@ -0,0 +1,1248 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * MQ Deadline i/o scheduler - adaptation of the legacy deadline scheduler, + * for the blk-mq scheduling framework + * + * Copyright (C) 2016 Jens Axboe <axboe@kernel.dk> + */ +#include <linux/kernel.h> +#include <linux/fs.h> +#include <linux/blkdev.h> +#include <linux/blk-mq.h> +#include <linux/bio.h> +#include <linux/module.h> +#include <linux/slab.h> +#include <linux/init.h> +#include <linux/compiler.h> +#include <linux/rbtree.h> +#include <linux/sbitmap.h> + +#include <trace/events/block.h> + +#include "elevator.h" +#include "blk.h" +#include "blk-mq.h" +#include "blk-mq-debugfs.h" +#include "blk-mq-tag.h" +#include "blk-mq-sched.h" + +/* + * See Documentation/block/deadline-iosched.rst + */ +static const int read_expire = HZ / 2; /* max time before a read is submitted. */ +static const int write_expire = 5 * HZ; /* ditto for writes, these limits are SOFT! */ +/* + * Time after which to dispatch lower priority requests even if higher + * priority requests are pending. + */ +static const int prio_aging_expire = 10 * HZ; +static const int writes_starved = 2; /* max times reads can starve a write */ +static const int fifo_batch = 16; /* # of sequential requests treated as one + by the above parameters. For throughput. */ + +enum dd_data_dir { + DD_READ = READ, + DD_WRITE = WRITE, +}; + +enum { DD_DIR_COUNT = 2 }; + +enum dd_prio { + DD_RT_PRIO = 0, + DD_BE_PRIO = 1, + DD_IDLE_PRIO = 2, + DD_PRIO_MAX = 2, +}; + +enum { DD_PRIO_COUNT = 3 }; + +/* + * I/O statistics per I/O priority. It is fine if these counters overflow. + * What matters is that these counters are at least as wide as + * log2(max_outstanding_requests). + */ +struct io_stats_per_prio { + uint32_t inserted; + uint32_t merged; + uint32_t dispatched; + atomic_t completed; +}; + +/* + * Deadline scheduler data per I/O priority (enum dd_prio). Requests are + * present on both sort_list[] and fifo_list[]. + */ +struct dd_per_prio { + struct list_head dispatch; + struct rb_root sort_list[DD_DIR_COUNT]; + struct list_head fifo_list[DD_DIR_COUNT]; + /* Next request in FIFO order. Read, write or both are NULL. */ + struct request *next_rq[DD_DIR_COUNT]; + struct io_stats_per_prio stats; +}; + +struct deadline_data { + /* + * run time data + */ + + struct dd_per_prio per_prio[DD_PRIO_COUNT]; + + /* Data direction of latest dispatched request. */ + enum dd_data_dir last_dir; + unsigned int batching; /* number of sequential requests made */ + unsigned int starved; /* times reads have starved writes */ + + /* + * settings that change how the i/o scheduler behaves + */ + int fifo_expire[DD_DIR_COUNT]; + int fifo_batch; + int writes_starved; + int front_merges; + u32 async_depth; + int prio_aging_expire; + + spinlock_t lock; + spinlock_t zone_lock; +}; + +/* Maps an I/O priority class to a deadline scheduler priority. */ +static const enum dd_prio ioprio_class_to_prio[] = { + [IOPRIO_CLASS_NONE] = DD_BE_PRIO, + [IOPRIO_CLASS_RT] = DD_RT_PRIO, + [IOPRIO_CLASS_BE] = DD_BE_PRIO, + [IOPRIO_CLASS_IDLE] = DD_IDLE_PRIO, +}; + +static inline struct rb_root * +deadline_rb_root(struct dd_per_prio *per_prio, struct request *rq) +{ + return &per_prio->sort_list[rq_data_dir(rq)]; +} + +/* + * Returns the I/O priority class (IOPRIO_CLASS_*) that has been assigned to a + * request. + */ +static u8 dd_rq_ioclass(struct request *rq) +{ + return IOPRIO_PRIO_CLASS(req_get_ioprio(rq)); +} + +/* + * get the request before `rq' in sector-sorted order + */ +static inline struct request * +deadline_earlier_request(struct request *rq) +{ + struct rb_node *node = rb_prev(&rq->rb_node); + + if (node) + return rb_entry_rq(node); + + return NULL; +} + +/* + * get the request after `rq' in sector-sorted order + */ +static inline struct request * +deadline_latter_request(struct request *rq) +{ + struct rb_node *node = rb_next(&rq->rb_node); + + if (node) + return rb_entry_rq(node); + + return NULL; +} + +static void +deadline_add_rq_rb(struct dd_per_prio *per_prio, struct request *rq) +{ + struct rb_root *root = deadline_rb_root(per_prio, rq); + + elv_rb_add(root, rq); +} + +static inline void +deadline_del_rq_rb(struct dd_per_prio *per_prio, struct request *rq) +{ + const enum dd_data_dir data_dir = rq_data_dir(rq); + + if (per_prio->next_rq[data_dir] == rq) + per_prio->next_rq[data_dir] = deadline_latter_request(rq); + + elv_rb_del(deadline_rb_root(per_prio, rq), rq); +} + +/* + * remove rq from rbtree and fifo. + */ +static void deadline_remove_request(struct request_queue *q, + struct dd_per_prio *per_prio, + struct request *rq) +{ + list_del_init(&rq->queuelist); + + /* + * We might not be on the rbtree, if we are doing an insert merge + */ + if (!RB_EMPTY_NODE(&rq->rb_node)) + deadline_del_rq_rb(per_prio, rq); + + elv_rqhash_del(q, rq); + if (q->last_merge == rq) + q->last_merge = NULL; +} + +static void dd_request_merged(struct request_queue *q, struct request *req, + enum elv_merge type) +{ + struct deadline_data *dd = q->elevator->elevator_data; + const u8 ioprio_class = dd_rq_ioclass(req); + const enum dd_prio prio = ioprio_class_to_prio[ioprio_class]; + struct dd_per_prio *per_prio = &dd->per_prio[prio]; + + /* + * if the merge was a front merge, we need to reposition request + */ + if (type == ELEVATOR_FRONT_MERGE) { + elv_rb_del(deadline_rb_root(per_prio, req), req); + deadline_add_rq_rb(per_prio, req); + } +} + +/* + * Callback function that is invoked after @next has been merged into @req. + */ +static void dd_merged_requests(struct request_queue *q, struct request *req, + struct request *next) +{ + struct deadline_data *dd = q->elevator->elevator_data; + const u8 ioprio_class = dd_rq_ioclass(next); + const enum dd_prio prio = ioprio_class_to_prio[ioprio_class]; + + lockdep_assert_held(&dd->lock); + + dd->per_prio[prio].stats.merged++; + + /* + * if next expires before rq, assign its expire time to rq + * and move into next position (next will be deleted) in fifo + */ + if (!list_empty(&req->queuelist) && !list_empty(&next->queuelist)) { + if (time_before((unsigned long)next->fifo_time, + (unsigned long)req->fifo_time)) { + list_move(&req->queuelist, &next->queuelist); + req->fifo_time = next->fifo_time; + } + } + + /* + * kill knowledge of next, this one is a goner + */ + deadline_remove_request(q, &dd->per_prio[prio], next); +} + +/* + * move an entry to dispatch queue + */ +static void +deadline_move_request(struct deadline_data *dd, struct dd_per_prio *per_prio, + struct request *rq) +{ + const enum dd_data_dir data_dir = rq_data_dir(rq); + + per_prio->next_rq[data_dir] = deadline_latter_request(rq); + + /* + * take it off the sort and fifo list + */ + deadline_remove_request(rq->q, per_prio, rq); +} + +/* Number of requests queued for a given priority level. */ +static u32 dd_queued(struct deadline_data *dd, enum dd_prio prio) +{ + const struct io_stats_per_prio *stats = &dd->per_prio[prio].stats; + + lockdep_assert_held(&dd->lock); + + return stats->inserted - atomic_read(&stats->completed); +} + +/* + * deadline_check_fifo returns 0 if there are no expired requests on the fifo, + * 1 otherwise. Requires !list_empty(&dd->fifo_list[data_dir]) + */ +static inline int deadline_check_fifo(struct dd_per_prio *per_prio, + enum dd_data_dir data_dir) +{ + struct request *rq = rq_entry_fifo(per_prio->fifo_list[data_dir].next); + + /* + * rq is expired! + */ + if (time_after_eq(jiffies, (unsigned long)rq->fifo_time)) + return 1; + + return 0; +} + +/* + * Check if rq has a sequential request preceding it. + */ +static bool deadline_is_seq_write(struct deadline_data *dd, struct request *rq) +{ + struct request *prev = deadline_earlier_request(rq); + + if (!prev) + return false; + + return blk_rq_pos(prev) + blk_rq_sectors(prev) == blk_rq_pos(rq); +} + +/* + * Skip all write requests that are sequential from @rq, even if we cross + * a zone boundary. + */ +static struct request *deadline_skip_seq_writes(struct deadline_data *dd, + struct request *rq) +{ + sector_t pos = blk_rq_pos(rq); + sector_t skipped_sectors = 0; + + while (rq) { + if (blk_rq_pos(rq) != pos + skipped_sectors) + break; + skipped_sectors += blk_rq_sectors(rq); + rq = deadline_latter_request(rq); + } + + return rq; +} + +/* + * For the specified data direction, return the next request to + * dispatch using arrival ordered lists. + */ +static struct request * +deadline_fifo_request(struct deadline_data *dd, struct dd_per_prio *per_prio, + enum dd_data_dir data_dir) +{ + struct request *rq; + unsigned long flags; + + if (list_empty(&per_prio->fifo_list[data_dir])) + return NULL; + + rq = rq_entry_fifo(per_prio->fifo_list[data_dir].next); + if (data_dir == DD_READ || !blk_queue_is_zoned(rq->q)) + return rq; + + /* + * Look for a write request that can be dispatched, that is one with + * an unlocked target zone. For some HDDs, breaking a sequential + * write stream can lead to lower throughput, so make sure to preserve + * sequential write streams, even if that stream crosses into the next + * zones and these zones are unlocked. + */ + spin_lock_irqsave(&dd->zone_lock, flags); + list_for_each_entry(rq, &per_prio->fifo_list[DD_WRITE], queuelist) { + if (blk_req_can_dispatch_to_zone(rq) && + (blk_queue_nonrot(rq->q) || + !deadline_is_seq_write(dd, rq))) + goto out; + } + rq = NULL; +out: + spin_unlock_irqrestore(&dd->zone_lock, flags); + + return rq; +} + +/* + * For the specified data direction, return the next request to + * dispatch using sector position sorted lists. + */ +static struct request * +deadline_next_request(struct deadline_data *dd, struct dd_per_prio *per_prio, + enum dd_data_dir data_dir) +{ + struct request *rq; + unsigned long flags; + + rq = per_prio->next_rq[data_dir]; + if (!rq) + return NULL; + + if (data_dir == DD_READ || !blk_queue_is_zoned(rq->q)) + return rq; + + /* + * Look for a write request that can be dispatched, that is one with + * an unlocked target zone. For some HDDs, breaking a sequential + * write stream can lead to lower throughput, so make sure to preserve + * sequential write streams, even if that stream crosses into the next + * zones and these zones are unlocked. + */ + spin_lock_irqsave(&dd->zone_lock, flags); + while (rq) { + if (blk_req_can_dispatch_to_zone(rq)) + break; + if (blk_queue_nonrot(rq->q)) + rq = deadline_latter_request(rq); + else + rq = deadline_skip_seq_writes(dd, rq); + } + spin_unlock_irqrestore(&dd->zone_lock, flags); + + return rq; +} + +/* + * Returns true if and only if @rq started after @latest_start where + * @latest_start is in jiffies. + */ +static bool started_after(struct deadline_data *dd, struct request *rq, + unsigned long latest_start) +{ + unsigned long start_time = (unsigned long)rq->fifo_time; + + start_time -= dd->fifo_expire[rq_data_dir(rq)]; + + return time_after(start_time, latest_start); +} + +/* + * deadline_dispatch_requests selects the best request according to + * read/write expire, fifo_batch, etc and with a start time <= @latest_start. + */ +static struct request *__dd_dispatch_request(struct deadline_data *dd, + struct dd_per_prio *per_prio, + unsigned long latest_start) +{ + struct request *rq, *next_rq; + enum dd_data_dir data_dir; + enum dd_prio prio; + u8 ioprio_class; + + lockdep_assert_held(&dd->lock); + + if (!list_empty(&per_prio->dispatch)) { + rq = list_first_entry(&per_prio->dispatch, struct request, + queuelist); + if (started_after(dd, rq, latest_start)) + return NULL; + list_del_init(&rq->queuelist); + goto done; + } + + /* + * batches are currently reads XOR writes + */ + rq = deadline_next_request(dd, per_prio, dd->last_dir); + if (rq && dd->batching < dd->fifo_batch) + /* we have a next request are still entitled to batch */ + goto dispatch_request; + + /* + * at this point we are not running a batch. select the appropriate + * data direction (read / write) + */ + + if (!list_empty(&per_prio->fifo_list[DD_READ])) { + BUG_ON(RB_EMPTY_ROOT(&per_prio->sort_list[DD_READ])); + + if (deadline_fifo_request(dd, per_prio, DD_WRITE) && + (dd->starved++ >= dd->writes_starved)) + goto dispatch_writes; + + data_dir = DD_READ; + + goto dispatch_find_request; + } + + /* + * there are either no reads or writes have been starved + */ + + if (!list_empty(&per_prio->fifo_list[DD_WRITE])) { +dispatch_writes: + BUG_ON(RB_EMPTY_ROOT(&per_prio->sort_list[DD_WRITE])); + + dd->starved = 0; + + data_dir = DD_WRITE; + + goto dispatch_find_request; + } + + return NULL; + +dispatch_find_request: + /* + * we are not running a batch, find best request for selected data_dir + */ + next_rq = deadline_next_request(dd, per_prio, data_dir); + if (deadline_check_fifo(per_prio, data_dir) || !next_rq) { + /* + * A deadline has expired, the last request was in the other + * direction, or we have run out of higher-sectored requests. + * Start again from the request with the earliest expiry time. + */ + rq = deadline_fifo_request(dd, per_prio, data_dir); + } else { + /* + * The last req was the same dir and we have a next request in + * sort order. No expired requests so continue on from here. + */ + rq = next_rq; + } + + /* + * For a zoned block device, if we only have writes queued and none of + * them can be dispatched, rq will be NULL. + */ + if (!rq) + return NULL; + + dd->last_dir = data_dir; + dd->batching = 0; + +dispatch_request: + if (started_after(dd, rq, latest_start)) + return NULL; + + /* + * rq is the selected appropriate request. + */ + dd->batching++; + deadline_move_request(dd, per_prio, rq); +done: + ioprio_class = dd_rq_ioclass(rq); + prio = ioprio_class_to_prio[ioprio_class]; + dd->per_prio[prio].stats.dispatched++; + /* + * If the request needs its target zone locked, do it. + */ + blk_req_zone_write_lock(rq); + rq->rq_flags |= RQF_STARTED; + return rq; +} + +/* + * Check whether there are any requests with priority other than DD_RT_PRIO + * that were inserted more than prio_aging_expire jiffies ago. + */ +static struct request *dd_dispatch_prio_aged_requests(struct deadline_data *dd, + unsigned long now) +{ + struct request *rq; + enum dd_prio prio; + int prio_cnt; + + lockdep_assert_held(&dd->lock); + + prio_cnt = !!dd_queued(dd, DD_RT_PRIO) + !!dd_queued(dd, DD_BE_PRIO) + + !!dd_queued(dd, DD_IDLE_PRIO); + if (prio_cnt < 2) + return NULL; + + for (prio = DD_BE_PRIO; prio <= DD_PRIO_MAX; prio++) { + rq = __dd_dispatch_request(dd, &dd->per_prio[prio], + now - dd->prio_aging_expire); + if (rq) + return rq; + } + + return NULL; +} + +/* + * Called from blk_mq_run_hw_queue() -> __blk_mq_sched_dispatch_requests(). + * + * One confusing aspect here is that we get called for a specific + * hardware queue, but we may return a request that is for a + * different hardware queue. This is because mq-deadline has shared + * state for all hardware queues, in terms of sorting, FIFOs, etc. + */ +static struct request *dd_dispatch_request(struct blk_mq_hw_ctx *hctx) +{ + struct deadline_data *dd = hctx->queue->elevator->elevator_data; + const unsigned long now = jiffies; + struct request *rq; + enum dd_prio prio; + + spin_lock(&dd->lock); + rq = dd_dispatch_prio_aged_requests(dd, now); + if (rq) + goto unlock; + + /* + * Next, dispatch requests in priority order. Ignore lower priority + * requests if any higher priority requests are pending. + */ + for (prio = 0; prio <= DD_PRIO_MAX; prio++) { + rq = __dd_dispatch_request(dd, &dd->per_prio[prio], now); + if (rq || dd_queued(dd, prio)) + break; + } + +unlock: + spin_unlock(&dd->lock); + + return rq; +} + +/* + * Called by __blk_mq_alloc_request(). The shallow_depth value set by this + * function is used by __blk_mq_get_tag(). + */ +static void dd_limit_depth(blk_opf_t opf, struct blk_mq_alloc_data *data) +{ + struct deadline_data *dd = data->q->elevator->elevator_data; + + /* Do not throttle synchronous reads. */ + if (op_is_sync(opf) && !op_is_write(opf)) + return; + + /* + * Throttle asynchronous requests and writes such that these requests + * do not block the allocation of synchronous requests. + */ + data->shallow_depth = dd->async_depth; +} + +/* Called by blk_mq_update_nr_requests(). */ +static void dd_depth_updated(struct blk_mq_hw_ctx *hctx) +{ + struct request_queue *q = hctx->queue; + struct deadline_data *dd = q->elevator->elevator_data; + struct blk_mq_tags *tags = hctx->sched_tags; + unsigned int shift = tags->bitmap_tags.sb.shift; + + dd->async_depth = max(1U, 3 * (1U << shift) / 4); + + sbitmap_queue_min_shallow_depth(&tags->bitmap_tags, dd->async_depth); +} + +/* Called by blk_mq_init_hctx() and blk_mq_init_sched(). */ +static int dd_init_hctx(struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx) +{ + dd_depth_updated(hctx); + return 0; +} + +static void dd_exit_sched(struct elevator_queue *e) +{ + struct deadline_data *dd = e->elevator_data; + enum dd_prio prio; + + for (prio = 0; prio <= DD_PRIO_MAX; prio++) { + struct dd_per_prio *per_prio = &dd->per_prio[prio]; + const struct io_stats_per_prio *stats = &per_prio->stats; + uint32_t queued; + + WARN_ON_ONCE(!list_empty(&per_prio->fifo_list[DD_READ])); + WARN_ON_ONCE(!list_empty(&per_prio->fifo_list[DD_WRITE])); + + spin_lock(&dd->lock); + queued = dd_queued(dd, prio); + spin_unlock(&dd->lock); + + WARN_ONCE(queued != 0, + "statistics for priority %d: i %u m %u d %u c %u\n", + prio, stats->inserted, stats->merged, + stats->dispatched, atomic_read(&stats->completed)); + } + + kfree(dd); +} + +/* + * initialize elevator private data (deadline_data). + */ +static int dd_init_sched(struct request_queue *q, struct elevator_type *e) +{ + struct deadline_data *dd; + struct elevator_queue *eq; + enum dd_prio prio; + int ret = -ENOMEM; + + eq = elevator_alloc(q, e); + if (!eq) + return ret; + + dd = kzalloc_node(sizeof(*dd), GFP_KERNEL, q->node); + if (!dd) + goto put_eq; + + eq->elevator_data = dd; + + for (prio = 0; prio <= DD_PRIO_MAX; prio++) { + struct dd_per_prio *per_prio = &dd->per_prio[prio]; + + INIT_LIST_HEAD(&per_prio->dispatch); + INIT_LIST_HEAD(&per_prio->fifo_list[DD_READ]); + INIT_LIST_HEAD(&per_prio->fifo_list[DD_WRITE]); + per_prio->sort_list[DD_READ] = RB_ROOT; + per_prio->sort_list[DD_WRITE] = RB_ROOT; + } + dd->fifo_expire[DD_READ] = read_expire; + dd->fifo_expire[DD_WRITE] = write_expire; + dd->writes_starved = writes_starved; + dd->front_merges = 1; + dd->last_dir = DD_WRITE; + dd->fifo_batch = fifo_batch; + dd->prio_aging_expire = prio_aging_expire; + spin_lock_init(&dd->lock); + spin_lock_init(&dd->zone_lock); + + /* We dispatch from request queue wide instead of hw queue */ + blk_queue_flag_set(QUEUE_FLAG_SQ_SCHED, q); + + q->elevator = eq; + return 0; + +put_eq: + kobject_put(&eq->kobj); + return ret; +} + +/* + * Try to merge @bio into an existing request. If @bio has been merged into + * an existing request, store the pointer to that request into *@rq. + */ +static int dd_request_merge(struct request_queue *q, struct request **rq, + struct bio *bio) +{ + struct deadline_data *dd = q->elevator->elevator_data; + const u8 ioprio_class = IOPRIO_PRIO_CLASS(bio->bi_ioprio); + const enum dd_prio prio = ioprio_class_to_prio[ioprio_class]; + struct dd_per_prio *per_prio = &dd->per_prio[prio]; + sector_t sector = bio_end_sector(bio); + struct request *__rq; + + if (!dd->front_merges) + return ELEVATOR_NO_MERGE; + + __rq = elv_rb_find(&per_prio->sort_list[bio_data_dir(bio)], sector); + if (__rq) { + BUG_ON(sector != blk_rq_pos(__rq)); + + if (elv_bio_merge_ok(__rq, bio)) { + *rq = __rq; + if (blk_discard_mergable(__rq)) + return ELEVATOR_DISCARD_MERGE; + return ELEVATOR_FRONT_MERGE; + } + } + + return ELEVATOR_NO_MERGE; +} + +/* + * Attempt to merge a bio into an existing request. This function is called + * before @bio is associated with a request. + */ +static bool dd_bio_merge(struct request_queue *q, struct bio *bio, + unsigned int nr_segs) +{ + struct deadline_data *dd = q->elevator->elevator_data; + struct request *free = NULL; + bool ret; + + spin_lock(&dd->lock); + ret = blk_mq_sched_try_merge(q, bio, nr_segs, &free); + spin_unlock(&dd->lock); + + if (free) + blk_mq_free_request(free); + + return ret; +} + +/* + * add rq to rbtree and fifo + */ +static void dd_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq, + bool at_head) +{ + struct request_queue *q = hctx->queue; + struct deadline_data *dd = q->elevator->elevator_data; + const enum dd_data_dir data_dir = rq_data_dir(rq); + u16 ioprio = req_get_ioprio(rq); + u8 ioprio_class = IOPRIO_PRIO_CLASS(ioprio); + struct dd_per_prio *per_prio; + enum dd_prio prio; + LIST_HEAD(free); + + lockdep_assert_held(&dd->lock); + + /* + * This may be a requeue of a write request that has locked its + * target zone. If it is the case, this releases the zone lock. + */ + blk_req_zone_write_unlock(rq); + + prio = ioprio_class_to_prio[ioprio_class]; + per_prio = &dd->per_prio[prio]; + if (!rq->elv.priv[0]) { + per_prio->stats.inserted++; + rq->elv.priv[0] = (void *)(uintptr_t)1; + } + + if (blk_mq_sched_try_insert_merge(q, rq, &free)) { + blk_mq_free_requests(&free); + return; + } + + trace_block_rq_insert(rq); + + if (at_head) { + list_add(&rq->queuelist, &per_prio->dispatch); + rq->fifo_time = jiffies; + } else { + deadline_add_rq_rb(per_prio, rq); + + if (rq_mergeable(rq)) { + elv_rqhash_add(q, rq); + if (!q->last_merge) + q->last_merge = rq; + } + + /* + * set expire time and add to fifo list + */ + rq->fifo_time = jiffies + dd->fifo_expire[data_dir]; + list_add_tail(&rq->queuelist, &per_prio->fifo_list[data_dir]); + } +} + +/* + * Called from blk_mq_sched_insert_request() or blk_mq_sched_insert_requests(). + */ +static void dd_insert_requests(struct blk_mq_hw_ctx *hctx, + struct list_head *list, bool at_head) +{ + struct request_queue *q = hctx->queue; + struct deadline_data *dd = q->elevator->elevator_data; + + spin_lock(&dd->lock); + while (!list_empty(list)) { + struct request *rq; + + rq = list_first_entry(list, struct request, queuelist); + list_del_init(&rq->queuelist); + dd_insert_request(hctx, rq, at_head); + } + spin_unlock(&dd->lock); +} + +/* Callback from inside blk_mq_rq_ctx_init(). */ +static void dd_prepare_request(struct request *rq) +{ + rq->elv.priv[0] = NULL; +} + +static bool dd_has_write_work(struct blk_mq_hw_ctx *hctx) +{ + struct deadline_data *dd = hctx->queue->elevator->elevator_data; + enum dd_prio p; + + for (p = 0; p <= DD_PRIO_MAX; p++) + if (!list_empty_careful(&dd->per_prio[p].fifo_list[DD_WRITE])) + return true; + + return false; +} + +/* + * Callback from inside blk_mq_free_request(). + * + * For zoned block devices, write unlock the target zone of + * completed write requests. Do this while holding the zone lock + * spinlock so that the zone is never unlocked while deadline_fifo_request() + * or deadline_next_request() are executing. This function is called for + * all requests, whether or not these requests complete successfully. + * + * For a zoned block device, __dd_dispatch_request() may have stopped + * dispatching requests if all the queued requests are write requests directed + * at zones that are already locked due to on-going write requests. To ensure + * write request dispatch progress in this case, mark the queue as needing a + * restart to ensure that the queue is run again after completion of the + * request and zones being unlocked. + */ +static void dd_finish_request(struct request *rq) +{ + struct request_queue *q = rq->q; + struct deadline_data *dd = q->elevator->elevator_data; + const u8 ioprio_class = dd_rq_ioclass(rq); + const enum dd_prio prio = ioprio_class_to_prio[ioprio_class]; + struct dd_per_prio *per_prio = &dd->per_prio[prio]; + + /* + * The block layer core may call dd_finish_request() without having + * called dd_insert_requests(). Skip requests that bypassed I/O + * scheduling. See also blk_mq_request_bypass_insert(). + */ + if (!rq->elv.priv[0]) + return; + + atomic_inc(&per_prio->stats.completed); + + if (blk_queue_is_zoned(q)) { + unsigned long flags; + + spin_lock_irqsave(&dd->zone_lock, flags); + blk_req_zone_write_unlock(rq); + spin_unlock_irqrestore(&dd->zone_lock, flags); + + if (dd_has_write_work(rq->mq_hctx)) + blk_mq_sched_mark_restart_hctx(rq->mq_hctx); + } +} + +static bool dd_has_work_for_prio(struct dd_per_prio *per_prio) +{ + return !list_empty_careful(&per_prio->dispatch) || + !list_empty_careful(&per_prio->fifo_list[DD_READ]) || + !list_empty_careful(&per_prio->fifo_list[DD_WRITE]); +} + +static bool dd_has_work(struct blk_mq_hw_ctx *hctx) +{ + struct deadline_data *dd = hctx->queue->elevator->elevator_data; + enum dd_prio prio; + + for (prio = 0; prio <= DD_PRIO_MAX; prio++) + if (dd_has_work_for_prio(&dd->per_prio[prio])) + return true; + + return false; +} + +/* + * sysfs parts below + */ +#define SHOW_INT(__FUNC, __VAR) \ +static ssize_t __FUNC(struct elevator_queue *e, char *page) \ +{ \ + struct deadline_data *dd = e->elevator_data; \ + \ + return sysfs_emit(page, "%d\n", __VAR); \ +} +#define SHOW_JIFFIES(__FUNC, __VAR) SHOW_INT(__FUNC, jiffies_to_msecs(__VAR)) +SHOW_JIFFIES(deadline_read_expire_show, dd->fifo_expire[DD_READ]); +SHOW_JIFFIES(deadline_write_expire_show, dd->fifo_expire[DD_WRITE]); +SHOW_JIFFIES(deadline_prio_aging_expire_show, dd->prio_aging_expire); +SHOW_INT(deadline_writes_starved_show, dd->writes_starved); +SHOW_INT(deadline_front_merges_show, dd->front_merges); +SHOW_INT(deadline_async_depth_show, dd->async_depth); +SHOW_INT(deadline_fifo_batch_show, dd->fifo_batch); +#undef SHOW_INT +#undef SHOW_JIFFIES + +#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \ +static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \ +{ \ + struct deadline_data *dd = e->elevator_data; \ + int __data, __ret; \ + \ + __ret = kstrtoint(page, 0, &__data); \ + if (__ret < 0) \ + return __ret; \ + if (__data < (MIN)) \ + __data = (MIN); \ + else if (__data > (MAX)) \ + __data = (MAX); \ + *(__PTR) = __CONV(__data); \ + return count; \ +} +#define STORE_INT(__FUNC, __PTR, MIN, MAX) \ + STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, ) +#define STORE_JIFFIES(__FUNC, __PTR, MIN, MAX) \ + STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, msecs_to_jiffies) +STORE_JIFFIES(deadline_read_expire_store, &dd->fifo_expire[DD_READ], 0, INT_MAX); +STORE_JIFFIES(deadline_write_expire_store, &dd->fifo_expire[DD_WRITE], 0, INT_MAX); +STORE_JIFFIES(deadline_prio_aging_expire_store, &dd->prio_aging_expire, 0, INT_MAX); +STORE_INT(deadline_writes_starved_store, &dd->writes_starved, INT_MIN, INT_MAX); +STORE_INT(deadline_front_merges_store, &dd->front_merges, 0, 1); +STORE_INT(deadline_async_depth_store, &dd->async_depth, 1, INT_MAX); +STORE_INT(deadline_fifo_batch_store, &dd->fifo_batch, 0, INT_MAX); +#undef STORE_FUNCTION +#undef STORE_INT +#undef STORE_JIFFIES + +#define DD_ATTR(name) \ + __ATTR(name, 0644, deadline_##name##_show, deadline_##name##_store) + +static struct elv_fs_entry deadline_attrs[] = { + DD_ATTR(read_expire), + DD_ATTR(write_expire), + DD_ATTR(writes_starved), + DD_ATTR(front_merges), + DD_ATTR(async_depth), + DD_ATTR(fifo_batch), + DD_ATTR(prio_aging_expire), + __ATTR_NULL +}; + +#ifdef CONFIG_BLK_DEBUG_FS +#define DEADLINE_DEBUGFS_DDIR_ATTRS(prio, data_dir, name) \ +static void *deadline_##name##_fifo_start(struct seq_file *m, \ + loff_t *pos) \ + __acquires(&dd->lock) \ +{ \ + struct request_queue *q = m->private; \ + struct deadline_data *dd = q->elevator->elevator_data; \ + struct dd_per_prio *per_prio = &dd->per_prio[prio]; \ + \ + spin_lock(&dd->lock); \ + return seq_list_start(&per_prio->fifo_list[data_dir], *pos); \ +} \ + \ +static void *deadline_##name##_fifo_next(struct seq_file *m, void *v, \ + loff_t *pos) \ +{ \ + struct request_queue *q = m->private; \ + struct deadline_data *dd = q->elevator->elevator_data; \ + struct dd_per_prio *per_prio = &dd->per_prio[prio]; \ + \ + return seq_list_next(v, &per_prio->fifo_list[data_dir], pos); \ +} \ + \ +static void deadline_##name##_fifo_stop(struct seq_file *m, void *v) \ + __releases(&dd->lock) \ +{ \ + struct request_queue *q = m->private; \ + struct deadline_data *dd = q->elevator->elevator_data; \ + \ + spin_unlock(&dd->lock); \ +} \ + \ +static const struct seq_operations deadline_##name##_fifo_seq_ops = { \ + .start = deadline_##name##_fifo_start, \ + .next = deadline_##name##_fifo_next, \ + .stop = deadline_##name##_fifo_stop, \ + .show = blk_mq_debugfs_rq_show, \ +}; \ + \ +static int deadline_##name##_next_rq_show(void *data, \ + struct seq_file *m) \ +{ \ + struct request_queue *q = data; \ + struct deadline_data *dd = q->elevator->elevator_data; \ + struct dd_per_prio *per_prio = &dd->per_prio[prio]; \ + struct request *rq = per_prio->next_rq[data_dir]; \ + \ + if (rq) \ + __blk_mq_debugfs_rq_show(m, rq); \ + return 0; \ +} + +DEADLINE_DEBUGFS_DDIR_ATTRS(DD_RT_PRIO, DD_READ, read0); +DEADLINE_DEBUGFS_DDIR_ATTRS(DD_RT_PRIO, DD_WRITE, write0); +DEADLINE_DEBUGFS_DDIR_ATTRS(DD_BE_PRIO, DD_READ, read1); +DEADLINE_DEBUGFS_DDIR_ATTRS(DD_BE_PRIO, DD_WRITE, write1); +DEADLINE_DEBUGFS_DDIR_ATTRS(DD_IDLE_PRIO, DD_READ, read2); +DEADLINE_DEBUGFS_DDIR_ATTRS(DD_IDLE_PRIO, DD_WRITE, write2); +#undef DEADLINE_DEBUGFS_DDIR_ATTRS + +static int deadline_batching_show(void *data, struct seq_file *m) +{ + struct request_queue *q = data; + struct deadline_data *dd = q->elevator->elevator_data; + + seq_printf(m, "%u\n", dd->batching); + return 0; +} + +static int deadline_starved_show(void *data, struct seq_file *m) +{ + struct request_queue *q = data; + struct deadline_data *dd = q->elevator->elevator_data; + + seq_printf(m, "%u\n", dd->starved); + return 0; +} + +static int dd_async_depth_show(void *data, struct seq_file *m) +{ + struct request_queue *q = data; + struct deadline_data *dd = q->elevator->elevator_data; + + seq_printf(m, "%u\n", dd->async_depth); + return 0; +} + +static int dd_queued_show(void *data, struct seq_file *m) +{ + struct request_queue *q = data; + struct deadline_data *dd = q->elevator->elevator_data; + u32 rt, be, idle; + + spin_lock(&dd->lock); + rt = dd_queued(dd, DD_RT_PRIO); + be = dd_queued(dd, DD_BE_PRIO); + idle = dd_queued(dd, DD_IDLE_PRIO); + spin_unlock(&dd->lock); + + seq_printf(m, "%u %u %u\n", rt, be, idle); + + return 0; +} + +/* Number of requests owned by the block driver for a given priority. */ +static u32 dd_owned_by_driver(struct deadline_data *dd, enum dd_prio prio) +{ + const struct io_stats_per_prio *stats = &dd->per_prio[prio].stats; + + lockdep_assert_held(&dd->lock); + + return stats->dispatched + stats->merged - + atomic_read(&stats->completed); +} + +static int dd_owned_by_driver_show(void *data, struct seq_file *m) +{ + struct request_queue *q = data; + struct deadline_data *dd = q->elevator->elevator_data; + u32 rt, be, idle; + + spin_lock(&dd->lock); + rt = dd_owned_by_driver(dd, DD_RT_PRIO); + be = dd_owned_by_driver(dd, DD_BE_PRIO); + idle = dd_owned_by_driver(dd, DD_IDLE_PRIO); + spin_unlock(&dd->lock); + + seq_printf(m, "%u %u %u\n", rt, be, idle); + + return 0; +} + +#define DEADLINE_DISPATCH_ATTR(prio) \ +static void *deadline_dispatch##prio##_start(struct seq_file *m, \ + loff_t *pos) \ + __acquires(&dd->lock) \ +{ \ + struct request_queue *q = m->private; \ + struct deadline_data *dd = q->elevator->elevator_data; \ + struct dd_per_prio *per_prio = &dd->per_prio[prio]; \ + \ + spin_lock(&dd->lock); \ + return seq_list_start(&per_prio->dispatch, *pos); \ +} \ + \ +static void *deadline_dispatch##prio##_next(struct seq_file *m, \ + void *v, loff_t *pos) \ +{ \ + struct request_queue *q = m->private; \ + struct deadline_data *dd = q->elevator->elevator_data; \ + struct dd_per_prio *per_prio = &dd->per_prio[prio]; \ + \ + return seq_list_next(v, &per_prio->dispatch, pos); \ +} \ + \ +static void deadline_dispatch##prio##_stop(struct seq_file *m, void *v) \ + __releases(&dd->lock) \ +{ \ + struct request_queue *q = m->private; \ + struct deadline_data *dd = q->elevator->elevator_data; \ + \ + spin_unlock(&dd->lock); \ +} \ + \ +static const struct seq_operations deadline_dispatch##prio##_seq_ops = { \ + .start = deadline_dispatch##prio##_start, \ + .next = deadline_dispatch##prio##_next, \ + .stop = deadline_dispatch##prio##_stop, \ + .show = blk_mq_debugfs_rq_show, \ +} + +DEADLINE_DISPATCH_ATTR(0); +DEADLINE_DISPATCH_ATTR(1); +DEADLINE_DISPATCH_ATTR(2); +#undef DEADLINE_DISPATCH_ATTR + +#define DEADLINE_QUEUE_DDIR_ATTRS(name) \ + {#name "_fifo_list", 0400, \ + .seq_ops = &deadline_##name##_fifo_seq_ops} +#define DEADLINE_NEXT_RQ_ATTR(name) \ + {#name "_next_rq", 0400, deadline_##name##_next_rq_show} +static const struct blk_mq_debugfs_attr deadline_queue_debugfs_attrs[] = { + DEADLINE_QUEUE_DDIR_ATTRS(read0), + DEADLINE_QUEUE_DDIR_ATTRS(write0), + DEADLINE_QUEUE_DDIR_ATTRS(read1), + DEADLINE_QUEUE_DDIR_ATTRS(write1), + DEADLINE_QUEUE_DDIR_ATTRS(read2), + DEADLINE_QUEUE_DDIR_ATTRS(write2), + DEADLINE_NEXT_RQ_ATTR(read0), + DEADLINE_NEXT_RQ_ATTR(write0), + DEADLINE_NEXT_RQ_ATTR(read1), + DEADLINE_NEXT_RQ_ATTR(write1), + DEADLINE_NEXT_RQ_ATTR(read2), + DEADLINE_NEXT_RQ_ATTR(write2), + {"batching", 0400, deadline_batching_show}, + {"starved", 0400, deadline_starved_show}, + {"async_depth", 0400, dd_async_depth_show}, + {"dispatch0", 0400, .seq_ops = &deadline_dispatch0_seq_ops}, + {"dispatch1", 0400, .seq_ops = &deadline_dispatch1_seq_ops}, + {"dispatch2", 0400, .seq_ops = &deadline_dispatch2_seq_ops}, + {"owned_by_driver", 0400, dd_owned_by_driver_show}, + {"queued", 0400, dd_queued_show}, + {}, +}; +#undef DEADLINE_QUEUE_DDIR_ATTRS +#endif + +static struct elevator_type mq_deadline = { + .ops = { + .depth_updated = dd_depth_updated, + .limit_depth = dd_limit_depth, + .insert_requests = dd_insert_requests, + .dispatch_request = dd_dispatch_request, + .prepare_request = dd_prepare_request, + .finish_request = dd_finish_request, + .next_request = elv_rb_latter_request, + .former_request = elv_rb_former_request, + .bio_merge = dd_bio_merge, + .request_merge = dd_request_merge, + .requests_merged = dd_merged_requests, + .request_merged = dd_request_merged, + .has_work = dd_has_work, + .init_sched = dd_init_sched, + .exit_sched = dd_exit_sched, + .init_hctx = dd_init_hctx, + }, + +#ifdef CONFIG_BLK_DEBUG_FS + .queue_debugfs_attrs = deadline_queue_debugfs_attrs, +#endif + .elevator_attrs = deadline_attrs, + .elevator_name = "mq-deadline", + .elevator_alias = "deadline", + .elevator_features = ELEVATOR_F_ZBD_SEQ_WRITE, + .elevator_owner = THIS_MODULE, +}; +MODULE_ALIAS("mq-deadline-iosched"); + +static int __init deadline_init(void) +{ + return elv_register(&mq_deadline); +} + +static void __exit deadline_exit(void) +{ + elv_unregister(&mq_deadline); +} + +module_init(deadline_init); +module_exit(deadline_exit); + +MODULE_AUTHOR("Jens Axboe, Damien Le Moal and Bart Van Assche"); +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("MQ deadline IO scheduler"); |