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-rw-r--r--block/mq-deadline.c1290
1 files changed, 1290 insertions, 0 deletions
diff --git a/block/mq-deadline.c b/block/mq-deadline.c
new file mode 100644
index 0000000000..f958e79277
--- /dev/null
+++ b/block/mq-deadline.c
@@ -0,0 +1,1290 @@
+// 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/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-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];
+ /* Position of the most recently dispatched request. */
+ sector_t latest_pos[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;
+}
+
+/*
+ * Return the first request for which blk_rq_pos() >= @pos. For zoned devices,
+ * return the first request after the start of the zone containing @pos.
+ */
+static inline struct request *deadline_from_pos(struct dd_per_prio *per_prio,
+ enum dd_data_dir data_dir, sector_t pos)
+{
+ struct rb_node *node = per_prio->sort_list[data_dir].rb_node;
+ struct request *rq, *res = NULL;
+
+ if (!node)
+ return NULL;
+
+ rq = rb_entry_rq(node);
+ /*
+ * A zoned write may have been requeued with a starting position that
+ * is below that of the most recently dispatched request. Hence, for
+ * zoned writes, start searching from the start of a zone.
+ */
+ if (blk_rq_is_seq_zoned_write(rq))
+ pos = round_down(pos, rq->q->limits.chunk_sectors);
+
+ while (node) {
+ rq = rb_entry_rq(node);
+ if (blk_rq_pos(rq) >= pos) {
+ res = rq;
+ node = node->rb_left;
+ } else {
+ node = node->rb_right;
+ }
+ }
+ return res;
+}
+
+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)
+{
+ 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)
+{
+ /*
+ * 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 true if and only if there are expired requests
+ * in the FIFO list. Requires !list_empty(&dd->fifo_list[data_dir]).
+ */
+static inline bool 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);
+
+ return time_is_before_eq_jiffies((unsigned long)rq->fifo_time);
+}
+
+/*
+ * 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);
+
+ do {
+ pos += blk_rq_sectors(rq);
+ rq = deadline_latter_request(rq);
+ } while (rq && blk_rq_pos(rq) == pos);
+
+ 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, *rb_rq, *next;
+ 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_safe(rq, next, &per_prio->fifo_list[DD_WRITE],
+ queuelist) {
+ /* Check whether a prior request exists for the same zone. */
+ rb_rq = deadline_from_pos(per_prio, data_dir, blk_rq_pos(rq));
+ if (rb_rq && blk_rq_pos(rb_rq) < blk_rq_pos(rq))
+ rq = rb_rq;
+ 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 = deadline_from_pos(per_prio, data_dir,
+ per_prio->latest_pos[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);
+ data_dir = rq_data_dir(rq);
+ 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 and are still entitled to batch */
+ data_dir = rq_data_dir(rq);
+ 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].latest_pos[data_dir] = blk_rq_pos(rq);
+ 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,
+ blk_insert_t flags, struct list_head *free)
+{
+ 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;
+
+ 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))
+ return;
+
+ trace_block_rq_insert(rq);
+
+ if (flags & BLK_MQ_INSERT_AT_HEAD) {
+ list_add(&rq->queuelist, &per_prio->dispatch);
+ rq->fifo_time = jiffies;
+ } else {
+ struct list_head *insert_before;
+
+ 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];
+ insert_before = &per_prio->fifo_list[data_dir];
+#ifdef CONFIG_BLK_DEV_ZONED
+ /*
+ * Insert zoned writes such that requests are sorted by
+ * position per zone.
+ */
+ if (blk_rq_is_seq_zoned_write(rq)) {
+ struct request *rq2 = deadline_latter_request(rq);
+
+ if (rq2 && blk_rq_zone_no(rq2) == blk_rq_zone_no(rq))
+ insert_before = &rq2->queuelist;
+ }
+#endif
+ list_add_tail(&rq->queuelist, insert_before);
+ }
+}
+
+/*
+ * Called from blk_mq_insert_request() or blk_mq_dispatch_plug_list().
+ */
+static void dd_insert_requests(struct blk_mq_hw_ctx *hctx,
+ struct list_head *list,
+ blk_insert_t flags)
+{
+ struct request_queue *q = hctx->queue;
+ struct deadline_data *dd = q->elevator->elevator_data;
+ LIST_HEAD(free);
+
+ 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, flags, &free);
+ }
+ spin_unlock(&dd->lock);
+
+ blk_mq_free_requests(&free);
+}
+
+/* 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; \
+ \
+ rq = deadline_from_pos(per_prio, data_dir, \
+ per_prio->latest_pos[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");
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-12 08:11:49 +0000