help
MQ version of the deadline IO scheduler.
+config MQ_IOSCHED_DEADLINE_CGROUP
+ tristate
+ default y
+ depends on MQ_IOSCHED_DEADLINE
+ depends on BLK_CGROUP
+
config MQ_IOSCHED_KYBER
tristate "Kyber I/O scheduler"
default y
obj-$(CONFIG_BLK_CGROUP_IOLATENCY) += blk-iolatency.o
obj-$(CONFIG_BLK_CGROUP_IOCOST) += blk-iocost.o
obj-$(CONFIG_MQ_IOSCHED_DEADLINE) += mq-deadline.o
+mq-deadline-y += mq-deadline-main.o
+mq-deadline-$(CONFIG_MQ_IOSCHED_DEADLINE_CGROUP)+= mq-deadline-cgroup.o
obj-$(CONFIG_MQ_IOSCHED_KYBER) += kyber-iosched.o
bfq-y := bfq-iosched.o bfq-wf2q.o bfq-cgroup.o
obj-$(CONFIG_IOSCHED_BFQ) += bfq.o
--- /dev/null
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/blk-cgroup.h>
+#include <linux/ioprio.h>
+
+#include "mq-deadline-cgroup.h"
+
+static struct blkcg_policy dd_blkcg_policy;
+
+static struct blkcg_policy_data *dd_cpd_alloc(gfp_t gfp)
+{
+ struct dd_blkcg *pd;
+
+ pd = kzalloc(sizeof(*pd), gfp);
+ if (!pd)
+ return NULL;
+ pd->stats = alloc_percpu_gfp(typeof(*pd->stats),
+ GFP_KERNEL | __GFP_ZERO);
+ if (!pd->stats) {
+ kfree(pd);
+ return NULL;
+ }
+ return &pd->cpd;
+}
+
+static void dd_cpd_free(struct blkcg_policy_data *cpd)
+{
+ struct dd_blkcg *dd_blkcg = container_of(cpd, typeof(*dd_blkcg), cpd);
+
+ free_percpu(dd_blkcg->stats);
+ kfree(dd_blkcg);
+}
+
+static struct dd_blkcg *dd_blkcg_from_pd(struct blkg_policy_data *pd)
+{
+ return container_of(blkcg_to_cpd(pd->blkg->blkcg, &dd_blkcg_policy),
+ struct dd_blkcg, cpd);
+}
+
+/*
+ * Convert an association between a block cgroup and a request queue into a
+ * pointer to the mq-deadline information associated with a (blkcg, queue) pair.
+ */
+struct dd_blkcg *dd_blkcg_from_bio(struct bio *bio)
+{
+ struct blkg_policy_data *pd;
+
+ pd = blkg_to_pd(bio->bi_blkg, &dd_blkcg_policy);
+ if (!pd)
+ return NULL;
+
+ return dd_blkcg_from_pd(pd);
+}
+
+static size_t dd_pd_stat(struct blkg_policy_data *pd, char *buf, size_t size)
+{
+ static const char *const prio_class_name[] = {
+ [IOPRIO_CLASS_NONE] = "NONE",
+ [IOPRIO_CLASS_RT] = "RT",
+ [IOPRIO_CLASS_BE] = "BE",
+ [IOPRIO_CLASS_IDLE] = "IDLE",
+ };
+ struct dd_blkcg *blkcg = dd_blkcg_from_pd(pd);
+ int res = 0;
+ u8 prio;
+
+ for (prio = 0; prio < ARRAY_SIZE(blkcg->stats->stats); prio++)
+ res += scnprintf(buf + res, size - res,
+ " [%s] dispatched=%u inserted=%u merged=%u",
+ prio_class_name[prio],
+ ddcg_sum(blkcg, dispatched, prio) +
+ ddcg_sum(blkcg, merged, prio) -
+ ddcg_sum(blkcg, completed, prio),
+ ddcg_sum(blkcg, inserted, prio) -
+ ddcg_sum(blkcg, completed, prio),
+ ddcg_sum(blkcg, merged, prio));
+
+ return res;
+}
+
+static struct blkg_policy_data *dd_pd_alloc(gfp_t gfp, struct request_queue *q,
+ struct blkcg *blkcg)
+{
+ struct dd_blkg *pd;
+
+ pd = kzalloc(sizeof(*pd), gfp);
+ if (!pd)
+ return NULL;
+ return &pd->pd;
+}
+
+static void dd_pd_free(struct blkg_policy_data *pd)
+{
+ struct dd_blkg *dd_blkg = container_of(pd, typeof(*dd_blkg), pd);
+
+ kfree(dd_blkg);
+}
+
+static struct blkcg_policy dd_blkcg_policy = {
+ .cpd_alloc_fn = dd_cpd_alloc,
+ .cpd_free_fn = dd_cpd_free,
+
+ .pd_alloc_fn = dd_pd_alloc,
+ .pd_free_fn = dd_pd_free,
+ .pd_stat_fn = dd_pd_stat,
+};
+
+int dd_activate_policy(struct request_queue *q)
+{
+ return blkcg_activate_policy(q, &dd_blkcg_policy);
+}
+
+void dd_deactivate_policy(struct request_queue *q)
+{
+ blkcg_deactivate_policy(q, &dd_blkcg_policy);
+}
+
+int __init dd_blkcg_init(void)
+{
+ return blkcg_policy_register(&dd_blkcg_policy);
+}
+
+void __exit dd_blkcg_exit(void)
+{
+ blkcg_policy_unregister(&dd_blkcg_policy);
+}
--- /dev/null
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#if !defined(_MQ_DEADLINE_CGROUP_H_)
+#define _MQ_DEADLINE_CGROUP_H_
+
+#include <linux/blk-cgroup.h>
+
+struct request_queue;
+
+/**
+ * struct io_stats_per_prio - I/O statistics per I/O priority class.
+ * @inserted: Number of inserted requests.
+ * @merged: Number of merged requests.
+ * @dispatched: Number of dispatched requests.
+ * @completed: Number of I/O completions.
+ */
+struct io_stats_per_prio {
+ local_t inserted;
+ local_t merged;
+ local_t dispatched;
+ local_t completed;
+};
+
+/* I/O statistics per I/O cgroup per I/O priority class (IOPRIO_CLASS_*). */
+struct blkcg_io_stats {
+ struct io_stats_per_prio stats[4];
+};
+
+/**
+ * struct dd_blkcg - Per cgroup data.
+ * @cpd: blkcg_policy_data structure.
+ * @stats: I/O statistics.
+ */
+struct dd_blkcg {
+ struct blkcg_policy_data cpd; /* must be the first member */
+ struct blkcg_io_stats __percpu *stats;
+};
+
+/*
+ * Count one event of type 'event_type' and with I/O priority class
+ * 'prio_class'.
+ */
+#define ddcg_count(ddcg, event_type, prio_class) do { \
+if (ddcg) { \
+ struct blkcg_io_stats *io_stats = get_cpu_ptr((ddcg)->stats); \
+ \
+ BUILD_BUG_ON(!__same_type((ddcg), struct dd_blkcg *)); \
+ BUILD_BUG_ON(!__same_type((prio_class), u8)); \
+ local_inc(&io_stats->stats[(prio_class)].event_type); \
+ put_cpu_ptr(io_stats); \
+} \
+} while (0)
+
+/*
+ * Returns the total number of ddcg_count(ddcg, event_type, prio_class) calls
+ * across all CPUs. No locking or barriers since it is fine if the returned
+ * sum is slightly outdated.
+ */
+#define ddcg_sum(ddcg, event_type, prio) ({ \
+ unsigned int cpu; \
+ u32 sum = 0; \
+ \
+ BUILD_BUG_ON(!__same_type((ddcg), struct dd_blkcg *)); \
+ BUILD_BUG_ON(!__same_type((prio), u8)); \
+ for_each_present_cpu(cpu) \
+ sum += local_read(&per_cpu_ptr((ddcg)->stats, cpu)-> \
+ stats[(prio)].event_type); \
+ sum; \
+})
+
+#ifdef CONFIG_BLK_CGROUP
+
+/**
+ * struct dd_blkg - Per (cgroup, request queue) data.
+ * @pd: blkg_policy_data structure.
+ */
+struct dd_blkg {
+ struct blkg_policy_data pd; /* must be the first member */
+};
+
+struct dd_blkcg *dd_blkcg_from_bio(struct bio *bio);
+int dd_activate_policy(struct request_queue *q);
+void dd_deactivate_policy(struct request_queue *q);
+int __init dd_blkcg_init(void);
+void __exit dd_blkcg_exit(void);
+
+#else /* CONFIG_BLK_CGROUP */
+
+static inline struct dd_blkcg *dd_blkcg_from_bio(struct bio *bio)
+{
+ return NULL;
+}
+
+static inline int dd_activate_policy(struct request_queue *q)
+{
+ return 0;
+}
+
+static inline void dd_deactivate_policy(struct request_queue *q)
+{
+}
+
+static inline int dd_blkcg_init(void)
+{
+ return 0;
+}
+
+static inline void dd_blkcg_exit(void)
+{
+}
+
+#endif /* CONFIG_BLK_CGROUP */
+
+#endif /* _MQ_DEADLINE_CGROUP_H_ */
--- /dev/null
+// 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"
+#include "mq-deadline-cgroup.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! */
+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 for all I/O priorities (enum dd_prio). */
+struct io_stats {
+ struct io_stats_per_prio stats[DD_PRIO_COUNT];
+};
+
+/*
+ * 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 deadline_data {
+ /*
+ * run time data
+ */
+
+ /* Request queue that owns this data structure. */
+ struct request_queue *queue;
+
+ 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 */
+
+ struct io_stats __percpu *stats;
+
+ /*
+ * 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;
+
+ spinlock_t lock;
+ spinlock_t zone_lock;
+};
+
+/* Count one event of type 'event_type' and with I/O priority 'prio' */
+#define dd_count(dd, event_type, prio) do { \
+ struct io_stats *io_stats = get_cpu_ptr((dd)->stats); \
+ \
+ BUILD_BUG_ON(!__same_type((dd), struct deadline_data *)); \
+ BUILD_BUG_ON(!__same_type((prio), enum dd_prio)); \
+ local_inc(&io_stats->stats[(prio)].event_type); \
+ put_cpu_ptr(io_stats); \
+} while (0)
+
+/*
+ * Returns the total number of dd_count(dd, event_type, prio) calls across all
+ * CPUs. No locking or barriers since it is fine if the returned sum is slightly
+ * outdated.
+ */
+#define dd_sum(dd, event_type, prio) ({ \
+ unsigned int cpu; \
+ u32 sum = 0; \
+ \
+ BUILD_BUG_ON(!__same_type((dd), struct deadline_data *)); \
+ BUILD_BUG_ON(!__same_type((prio), enum dd_prio)); \
+ for_each_present_cpu(cpu) \
+ sum += local_read(&per_cpu_ptr((dd)->stats, cpu)-> \
+ stats[(prio)].event_type); \
+ sum; \
+})
+
+/* 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 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];
+ struct dd_blkcg *blkcg = next->elv.priv[0];
+
+ dd_count(dd, merged, prio);
+ ddcg_count(blkcg, merged, ioprio_class);
+
+ /*
+ * 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)
+{
+ return dd_sum(dd, inserted, prio) - dd_sum(dd, completed, prio);
+}
+
+/*
+ * 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;
+}
+
+/*
+ * 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.
+ */
+ 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))
+ 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.
+ */
+ spin_lock_irqsave(&dd->zone_lock, flags);
+ while (rq) {
+ if (blk_req_can_dispatch_to_zone(rq))
+ break;
+ rq = deadline_latter_request(rq);
+ }
+ spin_unlock_irqrestore(&dd->zone_lock, flags);
+
+ return rq;
+}
+
+/*
+ * deadline_dispatch_requests selects the best request according to
+ * read/write expire, fifo_batch, etc
+ */
+static struct request *__dd_dispatch_request(struct deadline_data *dd,
+ struct dd_per_prio *per_prio)
+{
+ struct request *rq, *next_rq;
+ enum dd_data_dir data_dir;
+ struct dd_blkcg *blkcg;
+ 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);
+ 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:
+ /*
+ * 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_count(dd, dispatched, prio);
+ blkcg = rq->elv.priv[0];
+ ddcg_count(blkcg, dispatched, ioprio_class);
+ /*
+ * If the request needs its target zone locked, do it.
+ */
+ blk_req_zone_write_lock(rq);
+ rq->rq_flags |= RQF_STARTED;
+ return rq;
+}
+
+/*
+ * 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;
+ struct request *rq;
+ enum dd_prio prio;
+
+ spin_lock(&dd->lock);
+ for (prio = 0; prio <= DD_PRIO_MAX; prio++) {
+ rq = __dd_dispatch_request(dd, &dd->per_prio[prio]);
+ if (rq)
+ break;
+ }
+ 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;
+
+ dd->async_depth = max(1UL, 3 * q->nr_requests / 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;
+
+ dd_deactivate_policy(dd->queue);
+
+ for (prio = 0; prio <= DD_PRIO_MAX; prio++) {
+ struct dd_per_prio *per_prio = &dd->per_prio[prio];
+
+ WARN_ON_ONCE(!list_empty(&per_prio->fifo_list[DD_READ]));
+ WARN_ON_ONCE(!list_empty(&per_prio->fifo_list[DD_WRITE]));
+ }
+
+ free_percpu(dd->stats);
+
+ kfree(dd);
+}
+
+/*
+ * Initialize elevator private data (deadline_data) and associate with blkcg.
+ */
+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;
+
+ /*
+ * Initialization would be very tricky if the queue is not frozen,
+ * hence the warning statement below.
+ */
+ WARN_ON_ONCE(!percpu_ref_is_zero(&q->q_usage_counter));
+
+ 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;
+
+ dd->stats = alloc_percpu_gfp(typeof(*dd->stats),
+ GFP_KERNEL | __GFP_ZERO);
+ if (!dd->stats)
+ goto free_dd;
+
+ dd->queue = q;
+
+ 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;
+ spin_lock_init(&dd->lock);
+ spin_lock_init(&dd->zone_lock);
+
+ ret = dd_activate_policy(q);
+ if (ret)
+ goto free_stats;
+
+ ret = 0;
+ q->elevator = eq;
+ return 0;
+
+free_stats:
+ free_percpu(dd->stats);
+
+free_dd:
+ kfree(dd);
+
+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;
+ 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;
+ struct dd_blkcg *blkcg;
+
+ 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);
+
+ /*
+ * If a block cgroup has been associated with the submitter and if an
+ * I/O priority has been set in the associated block cgroup, use the
+ * lowest of the cgroup priority and the request priority for the
+ * request. If no priority has been set in the request, use the cgroup
+ * priority.
+ */
+ prio = ioprio_class_to_prio[ioprio_class];
+ dd_count(dd, inserted, prio);
+ blkcg = dd_blkcg_from_bio(rq->bio);
+ ddcg_count(blkcg, inserted, ioprio_class);
+ WARN_ON_ONCE(rq->elv.priv[0]);
+ rq->elv.priv[0] = blkcg;
+
+ if (blk_mq_sched_try_insert_merge(q, rq))
+ return;
+
+ trace_block_rq_insert(rq);
+
+ per_prio = &dd->per_prio[prio];
+ if (at_head) {
+ list_add(&rq->queuelist, &per_prio->dispatch);
+ } 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;
+}
+
+/*
+ * 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;
+ struct dd_blkcg *blkcg = rq->elv.priv[0];
+ 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];
+
+ dd_count(dd, completed, prio);
+ ddcg_count(blkcg, completed, ioprio_class);
+
+ if (blk_queue_is_zoned(q)) {
+ unsigned long flags;
+
+ spin_lock_irqsave(&dd->zone_lock, flags);
+ blk_req_zone_write_unlock(rq);
+ if (!list_empty(&per_prio->fifo_list[DD_WRITE]))
+ blk_mq_sched_mark_restart_hctx(rq->mq_hctx);
+ spin_unlock_irqrestore(&dd->zone_lock, flags);
+ }
+}
+
+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_INT(deadline_writes_starved_show, dd->writes_starved);
+SHOW_INT(deadline_front_merges_show, dd->front_merges);
+SHOW_INT(deadline_async_depth_show, dd->front_merges);
+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_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->front_merges, 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),
+ __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;
+
+ seq_printf(m, "%u %u %u\n", dd_queued(dd, DD_RT_PRIO),
+ dd_queued(dd, DD_BE_PRIO),
+ dd_queued(dd, DD_IDLE_PRIO));
+ 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)
+{
+ return dd_sum(dd, dispatched, prio) + dd_sum(dd, merged, prio)
+ - dd_sum(dd, completed, prio);
+}
+
+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;
+
+ seq_printf(m, "%u %u %u\n", dd_owned_by_driver(dd, DD_RT_PRIO),
+ dd_owned_by_driver(dd, DD_BE_PRIO),
+ dd_owned_by_driver(dd, DD_IDLE_PRIO));
+ 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)
+{
+ int ret;
+
+ ret = elv_register(&mq_deadline);
+ if (ret)
+ goto out;
+ ret = dd_blkcg_init();
+ if (ret)
+ goto unreg;
+
+out:
+ return ret;
+
+unreg:
+ elv_unregister(&mq_deadline);
+ goto out;
+}
+
+static void __exit deadline_exit(void)
+{
+ dd_blkcg_exit();
+ 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");
+++ /dev/null
-// 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! */
-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. */
-struct io_stats_per_prio {
- local_t inserted;
- local_t merged;
- local_t dispatched;
- local_t completed;
-};
-
-/* I/O statistics for all I/O priorities (enum dd_prio). */
-struct io_stats {
- struct io_stats_per_prio stats[DD_PRIO_COUNT];
-};
-
-/*
- * 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 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 */
-
- struct io_stats __percpu *stats;
-
- /*
- * 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;
-
- spinlock_t lock;
- spinlock_t zone_lock;
-};
-
-/* Count one event of type 'event_type' and with I/O priority 'prio' */
-#define dd_count(dd, event_type, prio) do { \
- struct io_stats *io_stats = get_cpu_ptr((dd)->stats); \
- \
- BUILD_BUG_ON(!__same_type((dd), struct deadline_data *)); \
- BUILD_BUG_ON(!__same_type((prio), enum dd_prio)); \
- local_inc(&io_stats->stats[(prio)].event_type); \
- put_cpu_ptr(io_stats); \
-} while (0)
-
-/*
- * Returns the total number of dd_count(dd, event_type, prio) calls across all
- * CPUs. No locking or barriers since it is fine if the returned sum is slightly
- * outdated.
- */
-#define dd_sum(dd, event_type, prio) ({ \
- unsigned int cpu; \
- u32 sum = 0; \
- \
- BUILD_BUG_ON(!__same_type((dd), struct deadline_data *)); \
- BUILD_BUG_ON(!__same_type((prio), enum dd_prio)); \
- for_each_present_cpu(cpu) \
- sum += local_read(&per_cpu_ptr((dd)->stats, cpu)-> \
- stats[(prio)].event_type); \
- sum; \
-})
-
-/* 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 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];
-
- dd_count(dd, merged, prio);
-
- /*
- * 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)
-{
- return dd_sum(dd, inserted, prio) - dd_sum(dd, completed, prio);
-}
-
-/*
- * 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;
-}
-
-/*
- * 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.
- */
- 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))
- 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.
- */
- spin_lock_irqsave(&dd->zone_lock, flags);
- while (rq) {
- if (blk_req_can_dispatch_to_zone(rq))
- break;
- rq = deadline_latter_request(rq);
- }
- spin_unlock_irqrestore(&dd->zone_lock, flags);
-
- return rq;
-}
-
-/*
- * deadline_dispatch_requests selects the best request according to
- * read/write expire, fifo_batch, etc
- */
-static struct request *__dd_dispatch_request(struct deadline_data *dd,
- struct dd_per_prio *per_prio)
-{
- 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);
- 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:
- /*
- * 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_count(dd, dispatched, prio);
- /*
- * If the request needs its target zone locked, do it.
- */
- blk_req_zone_write_lock(rq);
- rq->rq_flags |= RQF_STARTED;
- return rq;
-}
-
-/*
- * 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;
- struct request *rq;
- enum dd_prio prio;
-
- spin_lock(&dd->lock);
- for (prio = 0; prio <= DD_PRIO_MAX; prio++) {
- rq = __dd_dispatch_request(dd, &dd->per_prio[prio]);
- if (rq)
- break;
- }
- 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;
-
- dd->async_depth = max(1UL, 3 * q->nr_requests / 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];
-
- WARN_ON_ONCE(!list_empty(&per_prio->fifo_list[DD_READ]));
- WARN_ON_ONCE(!list_empty(&per_prio->fifo_list[DD_WRITE]));
- }
-
- free_percpu(dd->stats);
-
- 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;
-
- dd->stats = alloc_percpu_gfp(typeof(*dd->stats),
- GFP_KERNEL | __GFP_ZERO);
- if (!dd->stats)
- goto free_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;
- spin_lock_init(&dd->lock);
- spin_lock_init(&dd->zone_lock);
-
- q->elevator = eq;
- return 0;
-
-free_dd:
- kfree(dd);
-
-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;
- 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;
-
- 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];
- dd_count(dd, inserted, prio);
-
- if (blk_mq_sched_try_insert_merge(q, rq))
- return;
-
- trace_block_rq_insert(rq);
-
- per_prio = &dd->per_prio[prio];
- if (at_head) {
- list_add(&rq->queuelist, &per_prio->dispatch);
- } 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);
-}
-
-/*
- * Nothing to do here. This is defined only to ensure that .finish_request
- * method is called upon request completion.
- */
-static void dd_prepare_request(struct request *rq)
-{
-}
-
-/*
- * 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];
-
- dd_count(dd, completed, prio);
-
- if (blk_queue_is_zoned(q)) {
- unsigned long flags;
-
- spin_lock_irqsave(&dd->zone_lock, flags);
- blk_req_zone_write_unlock(rq);
- if (!list_empty(&per_prio->fifo_list[DD_WRITE]))
- blk_mq_sched_mark_restart_hctx(rq->mq_hctx);
- spin_unlock_irqrestore(&dd->zone_lock, flags);
- }
-}
-
-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_INT(deadline_writes_starved_show, dd->writes_starved);
-SHOW_INT(deadline_front_merges_show, dd->front_merges);
-SHOW_INT(deadline_async_depth_show, dd->front_merges);
-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_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->front_merges, 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),
- __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;
-
- seq_printf(m, "%u %u %u\n", dd_queued(dd, DD_RT_PRIO),
- dd_queued(dd, DD_BE_PRIO),
- dd_queued(dd, DD_IDLE_PRIO));
- 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)
-{
- return dd_sum(dd, dispatched, prio) + dd_sum(dd, merged, prio)
- - dd_sum(dd, completed, prio);
-}
-
-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;
-
- seq_printf(m, "%u %u %u\n", dd_owned_by_driver(dd, DD_RT_PRIO),
- dd_owned_by_driver(dd, DD_BE_PRIO),
- dd_owned_by_driver(dd, DD_IDLE_PRIO));
- 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");
projects / kernel.git / commitdiff