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93fffe16f7
Instead of passing a bool at_head, pass down the full flags from the blk_mq_insert_request interface. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Reviewed-by: Damien Le Moal <dlemoal@kernel.org> Link: https://lore.kernel.org/r/20230413064057.707578-20-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
1247 lines
34 KiB
C
1247 lines
34 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* MQ Deadline i/o scheduler - adaptation of the legacy deadline scheduler,
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* for the blk-mq scheduling framework
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*
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* Copyright (C) 2016 Jens Axboe <axboe@kernel.dk>
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*/
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#include <linux/kernel.h>
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#include <linux/fs.h>
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#include <linux/blkdev.h>
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#include <linux/bio.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/init.h>
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#include <linux/compiler.h>
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#include <linux/rbtree.h>
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#include <linux/sbitmap.h>
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#include <trace/events/block.h>
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#include "elevator.h"
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#include "blk.h"
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#include "blk-mq.h"
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#include "blk-mq-debugfs.h"
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#include "blk-mq-sched.h"
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/*
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* See Documentation/block/deadline-iosched.rst
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*/
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static const int read_expire = HZ / 2; /* max time before a read is submitted. */
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static const int write_expire = 5 * HZ; /* ditto for writes, these limits are SOFT! */
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/*
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* Time after which to dispatch lower priority requests even if higher
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* priority requests are pending.
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*/
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static const int prio_aging_expire = 10 * HZ;
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static const int writes_starved = 2; /* max times reads can starve a write */
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static const int fifo_batch = 16; /* # of sequential requests treated as one
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by the above parameters. For throughput. */
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enum dd_data_dir {
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DD_READ = READ,
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DD_WRITE = WRITE,
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};
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enum { DD_DIR_COUNT = 2 };
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enum dd_prio {
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DD_RT_PRIO = 0,
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DD_BE_PRIO = 1,
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DD_IDLE_PRIO = 2,
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DD_PRIO_MAX = 2,
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};
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enum { DD_PRIO_COUNT = 3 };
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/*
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* I/O statistics per I/O priority. It is fine if these counters overflow.
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* What matters is that these counters are at least as wide as
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* log2(max_outstanding_requests).
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*/
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struct io_stats_per_prio {
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uint32_t inserted;
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uint32_t merged;
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uint32_t dispatched;
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atomic_t completed;
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};
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/*
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* Deadline scheduler data per I/O priority (enum dd_prio). Requests are
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* present on both sort_list[] and fifo_list[].
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*/
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struct dd_per_prio {
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struct list_head dispatch;
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struct rb_root sort_list[DD_DIR_COUNT];
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struct list_head fifo_list[DD_DIR_COUNT];
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/* Next request in FIFO order. Read, write or both are NULL. */
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struct request *next_rq[DD_DIR_COUNT];
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struct io_stats_per_prio stats;
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};
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struct deadline_data {
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/*
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* run time data
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*/
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struct dd_per_prio per_prio[DD_PRIO_COUNT];
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/* Data direction of latest dispatched request. */
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enum dd_data_dir last_dir;
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unsigned int batching; /* number of sequential requests made */
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unsigned int starved; /* times reads have starved writes */
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/*
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* settings that change how the i/o scheduler behaves
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*/
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int fifo_expire[DD_DIR_COUNT];
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int fifo_batch;
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int writes_starved;
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int front_merges;
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u32 async_depth;
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int prio_aging_expire;
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spinlock_t lock;
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spinlock_t zone_lock;
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};
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/* Maps an I/O priority class to a deadline scheduler priority. */
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static const enum dd_prio ioprio_class_to_prio[] = {
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[IOPRIO_CLASS_NONE] = DD_BE_PRIO,
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[IOPRIO_CLASS_RT] = DD_RT_PRIO,
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[IOPRIO_CLASS_BE] = DD_BE_PRIO,
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[IOPRIO_CLASS_IDLE] = DD_IDLE_PRIO,
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};
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static inline struct rb_root *
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deadline_rb_root(struct dd_per_prio *per_prio, struct request *rq)
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{
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return &per_prio->sort_list[rq_data_dir(rq)];
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}
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/*
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* Returns the I/O priority class (IOPRIO_CLASS_*) that has been assigned to a
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* request.
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*/
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static u8 dd_rq_ioclass(struct request *rq)
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{
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return IOPRIO_PRIO_CLASS(req_get_ioprio(rq));
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}
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/*
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* get the request before `rq' in sector-sorted order
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*/
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static inline struct request *
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deadline_earlier_request(struct request *rq)
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{
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struct rb_node *node = rb_prev(&rq->rb_node);
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if (node)
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return rb_entry_rq(node);
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return NULL;
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}
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/*
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* get the request after `rq' in sector-sorted order
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*/
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static inline struct request *
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deadline_latter_request(struct request *rq)
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{
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struct rb_node *node = rb_next(&rq->rb_node);
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if (node)
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return rb_entry_rq(node);
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return NULL;
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}
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static void
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deadline_add_rq_rb(struct dd_per_prio *per_prio, struct request *rq)
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{
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struct rb_root *root = deadline_rb_root(per_prio, rq);
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elv_rb_add(root, rq);
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}
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static inline void
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deadline_del_rq_rb(struct dd_per_prio *per_prio, struct request *rq)
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{
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const enum dd_data_dir data_dir = rq_data_dir(rq);
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if (per_prio->next_rq[data_dir] == rq)
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per_prio->next_rq[data_dir] = deadline_latter_request(rq);
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elv_rb_del(deadline_rb_root(per_prio, rq), rq);
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}
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/*
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* remove rq from rbtree and fifo.
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*/
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static void deadline_remove_request(struct request_queue *q,
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struct dd_per_prio *per_prio,
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struct request *rq)
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{
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list_del_init(&rq->queuelist);
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/*
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* We might not be on the rbtree, if we are doing an insert merge
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*/
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if (!RB_EMPTY_NODE(&rq->rb_node))
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deadline_del_rq_rb(per_prio, rq);
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elv_rqhash_del(q, rq);
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if (q->last_merge == rq)
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q->last_merge = NULL;
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}
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static void dd_request_merged(struct request_queue *q, struct request *req,
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enum elv_merge type)
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{
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struct deadline_data *dd = q->elevator->elevator_data;
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const u8 ioprio_class = dd_rq_ioclass(req);
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const enum dd_prio prio = ioprio_class_to_prio[ioprio_class];
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struct dd_per_prio *per_prio = &dd->per_prio[prio];
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/*
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* if the merge was a front merge, we need to reposition request
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*/
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if (type == ELEVATOR_FRONT_MERGE) {
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elv_rb_del(deadline_rb_root(per_prio, req), req);
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deadline_add_rq_rb(per_prio, req);
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}
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}
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/*
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* Callback function that is invoked after @next has been merged into @req.
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*/
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static void dd_merged_requests(struct request_queue *q, struct request *req,
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struct request *next)
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{
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struct deadline_data *dd = q->elevator->elevator_data;
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const u8 ioprio_class = dd_rq_ioclass(next);
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const enum dd_prio prio = ioprio_class_to_prio[ioprio_class];
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lockdep_assert_held(&dd->lock);
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dd->per_prio[prio].stats.merged++;
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/*
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* if next expires before rq, assign its expire time to rq
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* and move into next position (next will be deleted) in fifo
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*/
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if (!list_empty(&req->queuelist) && !list_empty(&next->queuelist)) {
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if (time_before((unsigned long)next->fifo_time,
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(unsigned long)req->fifo_time)) {
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list_move(&req->queuelist, &next->queuelist);
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req->fifo_time = next->fifo_time;
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}
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}
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/*
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* kill knowledge of next, this one is a goner
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*/
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deadline_remove_request(q, &dd->per_prio[prio], next);
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}
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/*
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* move an entry to dispatch queue
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*/
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static void
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deadline_move_request(struct deadline_data *dd, struct dd_per_prio *per_prio,
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struct request *rq)
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{
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const enum dd_data_dir data_dir = rq_data_dir(rq);
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per_prio->next_rq[data_dir] = deadline_latter_request(rq);
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/*
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* take it off the sort and fifo list
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*/
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deadline_remove_request(rq->q, per_prio, rq);
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}
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/* Number of requests queued for a given priority level. */
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static u32 dd_queued(struct deadline_data *dd, enum dd_prio prio)
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{
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const struct io_stats_per_prio *stats = &dd->per_prio[prio].stats;
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lockdep_assert_held(&dd->lock);
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return stats->inserted - atomic_read(&stats->completed);
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}
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/*
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* deadline_check_fifo returns 0 if there are no expired requests on the fifo,
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* 1 otherwise. Requires !list_empty(&dd->fifo_list[data_dir])
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*/
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static inline int deadline_check_fifo(struct dd_per_prio *per_prio,
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enum dd_data_dir data_dir)
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{
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struct request *rq = rq_entry_fifo(per_prio->fifo_list[data_dir].next);
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/*
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* rq is expired!
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*/
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if (time_after_eq(jiffies, (unsigned long)rq->fifo_time))
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return 1;
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return 0;
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}
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/*
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* Check if rq has a sequential request preceding it.
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*/
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static bool deadline_is_seq_write(struct deadline_data *dd, struct request *rq)
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{
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struct request *prev = deadline_earlier_request(rq);
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if (!prev)
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return false;
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return blk_rq_pos(prev) + blk_rq_sectors(prev) == blk_rq_pos(rq);
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}
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/*
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* Skip all write requests that are sequential from @rq, even if we cross
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* a zone boundary.
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*/
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static struct request *deadline_skip_seq_writes(struct deadline_data *dd,
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struct request *rq)
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{
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sector_t pos = blk_rq_pos(rq);
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sector_t skipped_sectors = 0;
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while (rq) {
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if (blk_rq_pos(rq) != pos + skipped_sectors)
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break;
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skipped_sectors += blk_rq_sectors(rq);
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rq = deadline_latter_request(rq);
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}
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return rq;
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}
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/*
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* For the specified data direction, return the next request to
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* dispatch using arrival ordered lists.
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*/
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static struct request *
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deadline_fifo_request(struct deadline_data *dd, struct dd_per_prio *per_prio,
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enum dd_data_dir data_dir)
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{
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struct request *rq;
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unsigned long flags;
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if (list_empty(&per_prio->fifo_list[data_dir]))
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return NULL;
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rq = rq_entry_fifo(per_prio->fifo_list[data_dir].next);
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if (data_dir == DD_READ || !blk_queue_is_zoned(rq->q))
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return rq;
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/*
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* Look for a write request that can be dispatched, that is one with
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* an unlocked target zone. For some HDDs, breaking a sequential
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* write stream can lead to lower throughput, so make sure to preserve
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* sequential write streams, even if that stream crosses into the next
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* zones and these zones are unlocked.
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*/
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spin_lock_irqsave(&dd->zone_lock, flags);
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list_for_each_entry(rq, &per_prio->fifo_list[DD_WRITE], queuelist) {
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if (blk_req_can_dispatch_to_zone(rq) &&
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(blk_queue_nonrot(rq->q) ||
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!deadline_is_seq_write(dd, rq)))
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goto out;
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}
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rq = NULL;
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out:
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spin_unlock_irqrestore(&dd->zone_lock, flags);
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return rq;
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}
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/*
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* For the specified data direction, return the next request to
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* dispatch using sector position sorted lists.
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*/
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static struct request *
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deadline_next_request(struct deadline_data *dd, struct dd_per_prio *per_prio,
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enum dd_data_dir data_dir)
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{
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struct request *rq;
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unsigned long flags;
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rq = per_prio->next_rq[data_dir];
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if (!rq)
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return NULL;
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if (data_dir == DD_READ || !blk_queue_is_zoned(rq->q))
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return rq;
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/*
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* Look for a write request that can be dispatched, that is one with
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* an unlocked target zone. For some HDDs, breaking a sequential
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* write stream can lead to lower throughput, so make sure to preserve
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* sequential write streams, even if that stream crosses into the next
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* zones and these zones are unlocked.
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*/
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spin_lock_irqsave(&dd->zone_lock, flags);
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while (rq) {
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if (blk_req_can_dispatch_to_zone(rq))
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break;
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if (blk_queue_nonrot(rq->q))
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rq = deadline_latter_request(rq);
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else
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rq = deadline_skip_seq_writes(dd, rq);
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}
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spin_unlock_irqrestore(&dd->zone_lock, flags);
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return rq;
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}
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/*
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* Returns true if and only if @rq started after @latest_start where
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* @latest_start is in jiffies.
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*/
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static bool started_after(struct deadline_data *dd, struct request *rq,
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unsigned long latest_start)
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{
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unsigned long start_time = (unsigned long)rq->fifo_time;
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start_time -= dd->fifo_expire[rq_data_dir(rq)];
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return time_after(start_time, latest_start);
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}
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/*
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* deadline_dispatch_requests selects the best request according to
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* read/write expire, fifo_batch, etc and with a start time <= @latest_start.
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*/
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static struct request *__dd_dispatch_request(struct deadline_data *dd,
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struct dd_per_prio *per_prio,
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unsigned long latest_start)
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{
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struct request *rq, *next_rq;
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enum dd_data_dir data_dir;
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enum dd_prio prio;
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u8 ioprio_class;
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lockdep_assert_held(&dd->lock);
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if (!list_empty(&per_prio->dispatch)) {
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rq = list_first_entry(&per_prio->dispatch, struct request,
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queuelist);
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if (started_after(dd, rq, latest_start))
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return NULL;
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list_del_init(&rq->queuelist);
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goto done;
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}
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|
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/*
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* batches are currently reads XOR writes
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*/
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rq = deadline_next_request(dd, per_prio, dd->last_dir);
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if (rq && dd->batching < dd->fifo_batch)
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/* we have a next request are still entitled to batch */
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goto dispatch_request;
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/*
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* at this point we are not running a batch. select the appropriate
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* data direction (read / write)
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*/
|
|
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if (!list_empty(&per_prio->fifo_list[DD_READ])) {
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BUG_ON(RB_EMPTY_ROOT(&per_prio->sort_list[DD_READ]));
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if (deadline_fifo_request(dd, per_prio, DD_WRITE) &&
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(dd->starved++ >= dd->writes_starved))
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goto dispatch_writes;
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data_dir = DD_READ;
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goto dispatch_find_request;
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}
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|
|
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/*
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* there are either no reads or writes have been starved
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*/
|
|
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if (!list_empty(&per_prio->fifo_list[DD_WRITE])) {
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dispatch_writes:
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BUG_ON(RB_EMPTY_ROOT(&per_prio->sort_list[DD_WRITE]));
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|
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dd->starved = 0;
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|
|
|
data_dir = DD_WRITE;
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|
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goto dispatch_find_request;
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|
}
|
|
|
|
return NULL;
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|
|
|
dispatch_find_request:
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|
/*
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|
* we are not running a batch, find best request for selected data_dir
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*/
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next_rq = deadline_next_request(dd, per_prio, data_dir);
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|
if (deadline_check_fifo(per_prio, data_dir) || !next_rq) {
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|
/*
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|
* A deadline has expired, the last request was in the other
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* direction, or we have run out of higher-sectored requests.
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* Start again from the request with the earliest expiry time.
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*/
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rq = deadline_fifo_request(dd, per_prio, data_dir);
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|
} else {
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/*
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* The last req was the same dir and we have a next request in
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|
* sort order. No expired requests so continue on from here.
|
|
*/
|
|
rq = next_rq;
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|
}
|
|
|
|
/*
|
|
* For a zoned block device, if we only have writes queued and none of
|
|
* them can be dispatched, rq will be NULL.
|
|
*/
|
|
if (!rq)
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|
return NULL;
|
|
|
|
dd->last_dir = data_dir;
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|
dd->batching = 0;
|
|
|
|
dispatch_request:
|
|
if (started_after(dd, rq, latest_start))
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|
return NULL;
|
|
|
|
/*
|
|
* rq is the selected appropriate request.
|
|
*/
|
|
dd->batching++;
|
|
deadline_move_request(dd, per_prio, rq);
|
|
done:
|
|
ioprio_class = dd_rq_ioclass(rq);
|
|
prio = ioprio_class_to_prio[ioprio_class];
|
|
dd->per_prio[prio].stats.dispatched++;
|
|
/*
|
|
* If the request needs its target zone locked, do it.
|
|
*/
|
|
blk_req_zone_write_lock(rq);
|
|
rq->rq_flags |= RQF_STARTED;
|
|
return rq;
|
|
}
|
|
|
|
/*
|
|
* Check whether there are any requests with priority other than DD_RT_PRIO
|
|
* that were inserted more than prio_aging_expire jiffies ago.
|
|
*/
|
|
static struct request *dd_dispatch_prio_aged_requests(struct deadline_data *dd,
|
|
unsigned long now)
|
|
{
|
|
struct request *rq;
|
|
enum dd_prio prio;
|
|
int prio_cnt;
|
|
|
|
lockdep_assert_held(&dd->lock);
|
|
|
|
prio_cnt = !!dd_queued(dd, DD_RT_PRIO) + !!dd_queued(dd, DD_BE_PRIO) +
|
|
!!dd_queued(dd, DD_IDLE_PRIO);
|
|
if (prio_cnt < 2)
|
|
return NULL;
|
|
|
|
for (prio = DD_BE_PRIO; prio <= DD_PRIO_MAX; prio++) {
|
|
rq = __dd_dispatch_request(dd, &dd->per_prio[prio],
|
|
now - dd->prio_aging_expire);
|
|
if (rq)
|
|
return rq;
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* Called from blk_mq_run_hw_queue() -> __blk_mq_sched_dispatch_requests().
|
|
*
|
|
* One confusing aspect here is that we get called for a specific
|
|
* hardware queue, but we may return a request that is for a
|
|
* different hardware queue. This is because mq-deadline has shared
|
|
* state for all hardware queues, in terms of sorting, FIFOs, etc.
|
|
*/
|
|
static struct request *dd_dispatch_request(struct blk_mq_hw_ctx *hctx)
|
|
{
|
|
struct deadline_data *dd = hctx->queue->elevator->elevator_data;
|
|
const unsigned long now = jiffies;
|
|
struct request *rq;
|
|
enum dd_prio prio;
|
|
|
|
spin_lock(&dd->lock);
|
|
rq = dd_dispatch_prio_aged_requests(dd, now);
|
|
if (rq)
|
|
goto unlock;
|
|
|
|
/*
|
|
* Next, dispatch requests in priority order. Ignore lower priority
|
|
* requests if any higher priority requests are pending.
|
|
*/
|
|
for (prio = 0; prio <= DD_PRIO_MAX; prio++) {
|
|
rq = __dd_dispatch_request(dd, &dd->per_prio[prio], now);
|
|
if (rq || dd_queued(dd, prio))
|
|
break;
|
|
}
|
|
|
|
unlock:
|
|
spin_unlock(&dd->lock);
|
|
|
|
return rq;
|
|
}
|
|
|
|
/*
|
|
* Called by __blk_mq_alloc_request(). The shallow_depth value set by this
|
|
* function is used by __blk_mq_get_tag().
|
|
*/
|
|
static void dd_limit_depth(blk_opf_t opf, struct blk_mq_alloc_data *data)
|
|
{
|
|
struct deadline_data *dd = data->q->elevator->elevator_data;
|
|
|
|
/* Do not throttle synchronous reads. */
|
|
if (op_is_sync(opf) && !op_is_write(opf))
|
|
return;
|
|
|
|
/*
|
|
* Throttle asynchronous requests and writes such that these requests
|
|
* do not block the allocation of synchronous requests.
|
|
*/
|
|
data->shallow_depth = dd->async_depth;
|
|
}
|
|
|
|
/* Called by blk_mq_update_nr_requests(). */
|
|
static void dd_depth_updated(struct blk_mq_hw_ctx *hctx)
|
|
{
|
|
struct request_queue *q = hctx->queue;
|
|
struct deadline_data *dd = q->elevator->elevator_data;
|
|
struct blk_mq_tags *tags = hctx->sched_tags;
|
|
|
|
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];
|
|
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 request_queue *q = hctx->queue;
|
|
struct deadline_data *dd = q->elevator->elevator_data;
|
|
const enum dd_data_dir data_dir = rq_data_dir(rq);
|
|
u16 ioprio = req_get_ioprio(rq);
|
|
u8 ioprio_class = IOPRIO_PRIO_CLASS(ioprio);
|
|
struct dd_per_prio *per_prio;
|
|
enum dd_prio prio;
|
|
LIST_HEAD(free);
|
|
|
|
lockdep_assert_held(&dd->lock);
|
|
|
|
/*
|
|
* This may be a requeue of a write request that has locked its
|
|
* target zone. If it is the case, this releases the zone lock.
|
|
*/
|
|
blk_req_zone_write_unlock(rq);
|
|
|
|
prio = ioprio_class_to_prio[ioprio_class];
|
|
per_prio = &dd->per_prio[prio];
|
|
if (!rq->elv.priv[0]) {
|
|
per_prio->stats.inserted++;
|
|
rq->elv.priv[0] = (void *)(uintptr_t)1;
|
|
}
|
|
|
|
if (blk_mq_sched_try_insert_merge(q, rq, &free)) {
|
|
blk_mq_free_requests(&free);
|
|
return;
|
|
}
|
|
|
|
trace_block_rq_insert(rq);
|
|
|
|
if (flags & BLK_MQ_INSERT_AT_HEAD) {
|
|
list_add(&rq->queuelist, &per_prio->dispatch);
|
|
rq->fifo_time = jiffies;
|
|
} else {
|
|
deadline_add_rq_rb(per_prio, rq);
|
|
|
|
if (rq_mergeable(rq)) {
|
|
elv_rqhash_add(q, rq);
|
|
if (!q->last_merge)
|
|
q->last_merge = rq;
|
|
}
|
|
|
|
/*
|
|
* set expire time and add to fifo list
|
|
*/
|
|
rq->fifo_time = jiffies + dd->fifo_expire[data_dir];
|
|
list_add_tail(&rq->queuelist, &per_prio->fifo_list[data_dir]);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Called from blk_mq_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;
|
|
|
|
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);
|
|
}
|
|
spin_unlock(&dd->lock);
|
|
}
|
|
|
|
/* Callback from inside blk_mq_rq_ctx_init(). */
|
|
static void dd_prepare_request(struct request *rq)
|
|
{
|
|
rq->elv.priv[0] = NULL;
|
|
}
|
|
|
|
static bool dd_has_write_work(struct blk_mq_hw_ctx *hctx)
|
|
{
|
|
struct deadline_data *dd = hctx->queue->elevator->elevator_data;
|
|
enum dd_prio p;
|
|
|
|
for (p = 0; p <= DD_PRIO_MAX; p++)
|
|
if (!list_empty_careful(&dd->per_prio[p].fifo_list[DD_WRITE]))
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
/*
|
|
* Callback from inside blk_mq_free_request().
|
|
*
|
|
* For zoned block devices, write unlock the target zone of
|
|
* completed write requests. Do this while holding the zone lock
|
|
* spinlock so that the zone is never unlocked while deadline_fifo_request()
|
|
* or deadline_next_request() are executing. This function is called for
|
|
* all requests, whether or not these requests complete successfully.
|
|
*
|
|
* For a zoned block device, __dd_dispatch_request() may have stopped
|
|
* dispatching requests if all the queued requests are write requests directed
|
|
* at zones that are already locked due to on-going write requests. To ensure
|
|
* write request dispatch progress in this case, mark the queue as needing a
|
|
* restart to ensure that the queue is run again after completion of the
|
|
* request and zones being unlocked.
|
|
*/
|
|
static void dd_finish_request(struct request *rq)
|
|
{
|
|
struct request_queue *q = rq->q;
|
|
struct deadline_data *dd = q->elevator->elevator_data;
|
|
const u8 ioprio_class = dd_rq_ioclass(rq);
|
|
const enum dd_prio prio = ioprio_class_to_prio[ioprio_class];
|
|
struct dd_per_prio *per_prio = &dd->per_prio[prio];
|
|
|
|
/*
|
|
* The block layer core may call dd_finish_request() without having
|
|
* called dd_insert_requests(). Skip requests that bypassed I/O
|
|
* scheduling. See also blk_mq_request_bypass_insert().
|
|
*/
|
|
if (!rq->elv.priv[0])
|
|
return;
|
|
|
|
atomic_inc(&per_prio->stats.completed);
|
|
|
|
if (blk_queue_is_zoned(q)) {
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(&dd->zone_lock, flags);
|
|
blk_req_zone_write_unlock(rq);
|
|
spin_unlock_irqrestore(&dd->zone_lock, flags);
|
|
|
|
if (dd_has_write_work(rq->mq_hctx))
|
|
blk_mq_sched_mark_restart_hctx(rq->mq_hctx);
|
|
}
|
|
}
|
|
|
|
static bool dd_has_work_for_prio(struct dd_per_prio *per_prio)
|
|
{
|
|
return !list_empty_careful(&per_prio->dispatch) ||
|
|
!list_empty_careful(&per_prio->fifo_list[DD_READ]) ||
|
|
!list_empty_careful(&per_prio->fifo_list[DD_WRITE]);
|
|
}
|
|
|
|
static bool dd_has_work(struct blk_mq_hw_ctx *hctx)
|
|
{
|
|
struct deadline_data *dd = hctx->queue->elevator->elevator_data;
|
|
enum dd_prio prio;
|
|
|
|
for (prio = 0; prio <= DD_PRIO_MAX; prio++)
|
|
if (dd_has_work_for_prio(&dd->per_prio[prio]))
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
/*
|
|
* sysfs parts below
|
|
*/
|
|
#define SHOW_INT(__FUNC, __VAR) \
|
|
static ssize_t __FUNC(struct elevator_queue *e, char *page) \
|
|
{ \
|
|
struct deadline_data *dd = e->elevator_data; \
|
|
\
|
|
return sysfs_emit(page, "%d\n", __VAR); \
|
|
}
|
|
#define SHOW_JIFFIES(__FUNC, __VAR) SHOW_INT(__FUNC, jiffies_to_msecs(__VAR))
|
|
SHOW_JIFFIES(deadline_read_expire_show, dd->fifo_expire[DD_READ]);
|
|
SHOW_JIFFIES(deadline_write_expire_show, dd->fifo_expire[DD_WRITE]);
|
|
SHOW_JIFFIES(deadline_prio_aging_expire_show, dd->prio_aging_expire);
|
|
SHOW_INT(deadline_writes_starved_show, dd->writes_starved);
|
|
SHOW_INT(deadline_front_merges_show, dd->front_merges);
|
|
SHOW_INT(deadline_async_depth_show, dd->async_depth);
|
|
SHOW_INT(deadline_fifo_batch_show, dd->fifo_batch);
|
|
#undef SHOW_INT
|
|
#undef SHOW_JIFFIES
|
|
|
|
#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
|
|
static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
|
|
{ \
|
|
struct deadline_data *dd = e->elevator_data; \
|
|
int __data, __ret; \
|
|
\
|
|
__ret = kstrtoint(page, 0, &__data); \
|
|
if (__ret < 0) \
|
|
return __ret; \
|
|
if (__data < (MIN)) \
|
|
__data = (MIN); \
|
|
else if (__data > (MAX)) \
|
|
__data = (MAX); \
|
|
*(__PTR) = __CONV(__data); \
|
|
return count; \
|
|
}
|
|
#define STORE_INT(__FUNC, __PTR, MIN, MAX) \
|
|
STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, )
|
|
#define STORE_JIFFIES(__FUNC, __PTR, MIN, MAX) \
|
|
STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, msecs_to_jiffies)
|
|
STORE_JIFFIES(deadline_read_expire_store, &dd->fifo_expire[DD_READ], 0, INT_MAX);
|
|
STORE_JIFFIES(deadline_write_expire_store, &dd->fifo_expire[DD_WRITE], 0, INT_MAX);
|
|
STORE_JIFFIES(deadline_prio_aging_expire_store, &dd->prio_aging_expire, 0, INT_MAX);
|
|
STORE_INT(deadline_writes_starved_store, &dd->writes_starved, INT_MIN, INT_MAX);
|
|
STORE_INT(deadline_front_merges_store, &dd->front_merges, 0, 1);
|
|
STORE_INT(deadline_async_depth_store, &dd->async_depth, 1, INT_MAX);
|
|
STORE_INT(deadline_fifo_batch_store, &dd->fifo_batch, 0, INT_MAX);
|
|
#undef STORE_FUNCTION
|
|
#undef STORE_INT
|
|
#undef STORE_JIFFIES
|
|
|
|
#define DD_ATTR(name) \
|
|
__ATTR(name, 0644, deadline_##name##_show, deadline_##name##_store)
|
|
|
|
static struct elv_fs_entry deadline_attrs[] = {
|
|
DD_ATTR(read_expire),
|
|
DD_ATTR(write_expire),
|
|
DD_ATTR(writes_starved),
|
|
DD_ATTR(front_merges),
|
|
DD_ATTR(async_depth),
|
|
DD_ATTR(fifo_batch),
|
|
DD_ATTR(prio_aging_expire),
|
|
__ATTR_NULL
|
|
};
|
|
|
|
#ifdef CONFIG_BLK_DEBUG_FS
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#define DEADLINE_DEBUGFS_DDIR_ATTRS(prio, data_dir, name) \
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static void *deadline_##name##_fifo_start(struct seq_file *m, \
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loff_t *pos) \
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__acquires(&dd->lock) \
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{ \
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struct request_queue *q = m->private; \
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struct deadline_data *dd = q->elevator->elevator_data; \
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struct dd_per_prio *per_prio = &dd->per_prio[prio]; \
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\
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spin_lock(&dd->lock); \
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return seq_list_start(&per_prio->fifo_list[data_dir], *pos); \
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} \
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\
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static void *deadline_##name##_fifo_next(struct seq_file *m, void *v, \
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loff_t *pos) \
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{ \
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struct request_queue *q = m->private; \
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struct deadline_data *dd = q->elevator->elevator_data; \
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struct dd_per_prio *per_prio = &dd->per_prio[prio]; \
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\
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return seq_list_next(v, &per_prio->fifo_list[data_dir], pos); \
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} \
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\
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static void deadline_##name##_fifo_stop(struct seq_file *m, void *v) \
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__releases(&dd->lock) \
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{ \
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struct request_queue *q = m->private; \
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struct deadline_data *dd = q->elevator->elevator_data; \
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\
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spin_unlock(&dd->lock); \
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} \
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\
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static const struct seq_operations deadline_##name##_fifo_seq_ops = { \
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.start = deadline_##name##_fifo_start, \
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.next = deadline_##name##_fifo_next, \
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.stop = deadline_##name##_fifo_stop, \
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.show = blk_mq_debugfs_rq_show, \
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}; \
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\
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static int deadline_##name##_next_rq_show(void *data, \
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struct seq_file *m) \
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{ \
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struct request_queue *q = data; \
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struct deadline_data *dd = q->elevator->elevator_data; \
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struct dd_per_prio *per_prio = &dd->per_prio[prio]; \
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struct request *rq = per_prio->next_rq[data_dir]; \
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\
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if (rq) \
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__blk_mq_debugfs_rq_show(m, rq); \
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return 0; \
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}
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DEADLINE_DEBUGFS_DDIR_ATTRS(DD_RT_PRIO, DD_READ, read0);
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DEADLINE_DEBUGFS_DDIR_ATTRS(DD_RT_PRIO, DD_WRITE, write0);
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DEADLINE_DEBUGFS_DDIR_ATTRS(DD_BE_PRIO, DD_READ, read1);
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DEADLINE_DEBUGFS_DDIR_ATTRS(DD_BE_PRIO, DD_WRITE, write1);
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DEADLINE_DEBUGFS_DDIR_ATTRS(DD_IDLE_PRIO, DD_READ, read2);
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DEADLINE_DEBUGFS_DDIR_ATTRS(DD_IDLE_PRIO, DD_WRITE, write2);
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#undef DEADLINE_DEBUGFS_DDIR_ATTRS
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static int deadline_batching_show(void *data, struct seq_file *m)
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{
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struct request_queue *q = data;
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struct deadline_data *dd = q->elevator->elevator_data;
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seq_printf(m, "%u\n", dd->batching);
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return 0;
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}
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static int deadline_starved_show(void *data, struct seq_file *m)
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{
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struct request_queue *q = data;
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struct deadline_data *dd = q->elevator->elevator_data;
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seq_printf(m, "%u\n", dd->starved);
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return 0;
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}
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static int dd_async_depth_show(void *data, struct seq_file *m)
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{
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struct request_queue *q = data;
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struct deadline_data *dd = q->elevator->elevator_data;
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seq_printf(m, "%u\n", dd->async_depth);
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return 0;
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}
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static int dd_queued_show(void *data, struct seq_file *m)
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{
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struct request_queue *q = data;
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struct deadline_data *dd = q->elevator->elevator_data;
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u32 rt, be, idle;
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spin_lock(&dd->lock);
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rt = dd_queued(dd, DD_RT_PRIO);
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be = dd_queued(dd, DD_BE_PRIO);
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idle = dd_queued(dd, DD_IDLE_PRIO);
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spin_unlock(&dd->lock);
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seq_printf(m, "%u %u %u\n", rt, be, idle);
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return 0;
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}
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/* Number of requests owned by the block driver for a given priority. */
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static u32 dd_owned_by_driver(struct deadline_data *dd, enum dd_prio prio)
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{
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const struct io_stats_per_prio *stats = &dd->per_prio[prio].stats;
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lockdep_assert_held(&dd->lock);
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return stats->dispatched + stats->merged -
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atomic_read(&stats->completed);
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}
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static int dd_owned_by_driver_show(void *data, struct seq_file *m)
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{
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struct request_queue *q = data;
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struct deadline_data *dd = q->elevator->elevator_data;
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u32 rt, be, idle;
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spin_lock(&dd->lock);
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rt = dd_owned_by_driver(dd, DD_RT_PRIO);
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be = dd_owned_by_driver(dd, DD_BE_PRIO);
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idle = dd_owned_by_driver(dd, DD_IDLE_PRIO);
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spin_unlock(&dd->lock);
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seq_printf(m, "%u %u %u\n", rt, be, idle);
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return 0;
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}
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#define DEADLINE_DISPATCH_ATTR(prio) \
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static void *deadline_dispatch##prio##_start(struct seq_file *m, \
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loff_t *pos) \
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__acquires(&dd->lock) \
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{ \
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struct request_queue *q = m->private; \
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struct deadline_data *dd = q->elevator->elevator_data; \
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struct dd_per_prio *per_prio = &dd->per_prio[prio]; \
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\
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spin_lock(&dd->lock); \
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return seq_list_start(&per_prio->dispatch, *pos); \
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} \
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\
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static void *deadline_dispatch##prio##_next(struct seq_file *m, \
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void *v, loff_t *pos) \
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{ \
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struct request_queue *q = m->private; \
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struct deadline_data *dd = q->elevator->elevator_data; \
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struct dd_per_prio *per_prio = &dd->per_prio[prio]; \
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\
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return seq_list_next(v, &per_prio->dispatch, pos); \
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} \
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\
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static void deadline_dispatch##prio##_stop(struct seq_file *m, void *v) \
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__releases(&dd->lock) \
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{ \
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struct request_queue *q = m->private; \
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struct deadline_data *dd = q->elevator->elevator_data; \
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\
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spin_unlock(&dd->lock); \
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} \
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\
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static const struct seq_operations deadline_dispatch##prio##_seq_ops = { \
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.start = deadline_dispatch##prio##_start, \
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.next = deadline_dispatch##prio##_next, \
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.stop = deadline_dispatch##prio##_stop, \
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.show = blk_mq_debugfs_rq_show, \
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}
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DEADLINE_DISPATCH_ATTR(0);
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DEADLINE_DISPATCH_ATTR(1);
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DEADLINE_DISPATCH_ATTR(2);
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#undef DEADLINE_DISPATCH_ATTR
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#define DEADLINE_QUEUE_DDIR_ATTRS(name) \
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{#name "_fifo_list", 0400, \
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.seq_ops = &deadline_##name##_fifo_seq_ops}
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#define DEADLINE_NEXT_RQ_ATTR(name) \
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{#name "_next_rq", 0400, deadline_##name##_next_rq_show}
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static const struct blk_mq_debugfs_attr deadline_queue_debugfs_attrs[] = {
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DEADLINE_QUEUE_DDIR_ATTRS(read0),
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DEADLINE_QUEUE_DDIR_ATTRS(write0),
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DEADLINE_QUEUE_DDIR_ATTRS(read1),
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DEADLINE_QUEUE_DDIR_ATTRS(write1),
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DEADLINE_QUEUE_DDIR_ATTRS(read2),
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DEADLINE_QUEUE_DDIR_ATTRS(write2),
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DEADLINE_NEXT_RQ_ATTR(read0),
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DEADLINE_NEXT_RQ_ATTR(write0),
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DEADLINE_NEXT_RQ_ATTR(read1),
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DEADLINE_NEXT_RQ_ATTR(write1),
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DEADLINE_NEXT_RQ_ATTR(read2),
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DEADLINE_NEXT_RQ_ATTR(write2),
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{"batching", 0400, deadline_batching_show},
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{"starved", 0400, deadline_starved_show},
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{"async_depth", 0400, dd_async_depth_show},
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{"dispatch0", 0400, .seq_ops = &deadline_dispatch0_seq_ops},
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{"dispatch1", 0400, .seq_ops = &deadline_dispatch1_seq_ops},
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{"dispatch2", 0400, .seq_ops = &deadline_dispatch2_seq_ops},
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{"owned_by_driver", 0400, dd_owned_by_driver_show},
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{"queued", 0400, dd_queued_show},
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{},
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};
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#undef DEADLINE_QUEUE_DDIR_ATTRS
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#endif
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static struct elevator_type mq_deadline = {
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.ops = {
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.depth_updated = dd_depth_updated,
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.limit_depth = dd_limit_depth,
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.insert_requests = dd_insert_requests,
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.dispatch_request = dd_dispatch_request,
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.prepare_request = dd_prepare_request,
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.finish_request = dd_finish_request,
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.next_request = elv_rb_latter_request,
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.former_request = elv_rb_former_request,
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.bio_merge = dd_bio_merge,
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.request_merge = dd_request_merge,
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.requests_merged = dd_merged_requests,
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.request_merged = dd_request_merged,
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.has_work = dd_has_work,
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.init_sched = dd_init_sched,
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.exit_sched = dd_exit_sched,
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.init_hctx = dd_init_hctx,
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},
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#ifdef CONFIG_BLK_DEBUG_FS
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.queue_debugfs_attrs = deadline_queue_debugfs_attrs,
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#endif
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.elevator_attrs = deadline_attrs,
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.elevator_name = "mq-deadline",
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.elevator_alias = "deadline",
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.elevator_features = ELEVATOR_F_ZBD_SEQ_WRITE,
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.elevator_owner = THIS_MODULE,
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};
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MODULE_ALIAS("mq-deadline-iosched");
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static int __init deadline_init(void)
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{
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return elv_register(&mq_deadline);
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}
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static void __exit deadline_exit(void)
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{
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elv_unregister(&mq_deadline);
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}
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module_init(deadline_init);
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module_exit(deadline_exit);
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MODULE_AUTHOR("Jens Axboe, Damien Le Moal and Bart Van Assche");
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MODULE_LICENSE("GPL");
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MODULE_DESCRIPTION("MQ deadline IO scheduler");
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