| // 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/elevator.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 "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(unsigned int op, struct blk_mq_alloc_data *data) |
| { |
| struct deadline_data *dd = data->q->elevator->elevator_data; |
| |
| /* Do not throttle synchronous reads. */ |
| if (op_is_sync(op) && !op_is_write(op)) |
| 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); |
| |
| 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"); |