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1175 lines
32 KiB
1175 lines
32 KiB
// 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 <[email protected]> |
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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/blk-mq.h> |
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#include <linux/elevator.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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|
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#include <trace/events/block.h> |
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|
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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-tag.h" |
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#include "blk-mq-sched.h" |
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#include "mq-deadline-cgroup.h" |
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|
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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 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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|
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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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|
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enum { DD_DIR_COUNT = 2 }; |
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|
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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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|
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enum { DD_PRIO_COUNT = 3 }; |
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|
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/* I/O statistics for all I/O priorities (enum dd_prio). */ |
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struct io_stats { |
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struct io_stats_per_prio stats[DD_PRIO_COUNT]; |
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}; |
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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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}; |
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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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|
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/* Request queue that owns this data structure. */ |
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struct request_queue *queue; |
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|
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struct dd_per_prio per_prio[DD_PRIO_COUNT]; |
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|
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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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struct io_stats __percpu *stats; |
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|
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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 aging_expire; |
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|
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spinlock_t lock; |
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spinlock_t zone_lock; |
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}; |
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|
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/* Count one event of type 'event_type' and with I/O priority 'prio' */ |
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#define dd_count(dd, event_type, prio) do { \ |
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struct io_stats *io_stats = get_cpu_ptr((dd)->stats); \ |
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\ |
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BUILD_BUG_ON(!__same_type((dd), struct deadline_data *)); \ |
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BUILD_BUG_ON(!__same_type((prio), enum dd_prio)); \ |
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local_inc(&io_stats->stats[(prio)].event_type); \ |
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put_cpu_ptr(io_stats); \ |
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} while (0) |
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|
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/* |
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* Returns the total number of dd_count(dd, event_type, prio) calls across all |
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* CPUs. No locking or barriers since it is fine if the returned sum is slightly |
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* outdated. |
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*/ |
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#define dd_sum(dd, event_type, prio) ({ \ |
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unsigned int cpu; \ |
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u32 sum = 0; \ |
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\ |
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BUILD_BUG_ON(!__same_type((dd), struct deadline_data *)); \ |
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BUILD_BUG_ON(!__same_type((prio), enum dd_prio)); \ |
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for_each_present_cpu(cpu) \ |
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sum += local_read(&per_cpu_ptr((dd)->stats, cpu)-> \ |
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stats[(prio)].event_type); \ |
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sum; \ |
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}) |
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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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|
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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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/* |
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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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/* |
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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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|
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if (node) |
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return rb_entry_rq(node); |
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|
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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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|
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elv_rb_add(root, rq); |
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} |
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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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|
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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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/* |
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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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/* |
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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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|
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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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|
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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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/* |
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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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/* |
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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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struct dd_blkcg *blkcg = next->elv.priv[0]; |
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|
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dd_count(dd, merged, prio); |
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ddcg_count(blkcg, merged, ioprio_class); |
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|
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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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/* |
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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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/* |
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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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|
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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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return dd_sum(dd, inserted, prio) - dd_sum(dd, completed, prio); |
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} |
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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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/* |
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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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/* |
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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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/* |
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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. |
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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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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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/* |
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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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|
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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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|
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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. |
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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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rq = deadline_latter_request(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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/* |
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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. |
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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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u64 latest_start_ns) |
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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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struct dd_blkcg *blkcg; |
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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 (rq->start_time_ns > latest_start_ns) |
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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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* 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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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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* 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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dd->starved = 0; |
|
|
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data_dir = DD_WRITE; |
|
|
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goto dispatch_find_request; |
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} |
|
|
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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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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. |
|
* 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. |
|
*/ |
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rq = next_rq; |
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} |
|
|
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/* |
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* For a zoned block device, if we only have writes queued and none of |
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* them can be dispatched, rq will be NULL. |
|
*/ |
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if (!rq) |
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return NULL; |
|
|
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dd->last_dir = data_dir; |
|
dd->batching = 0; |
|
|
|
dispatch_request: |
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if (rq->start_time_ns > latest_start_ns) |
|
return NULL; |
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/* |
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* rq is the selected appropriate request. |
|
*/ |
|
dd->batching++; |
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deadline_move_request(dd, per_prio, rq); |
|
done: |
|
ioprio_class = dd_rq_ioclass(rq); |
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prio = ioprio_class_to_prio[ioprio_class]; |
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dd_count(dd, dispatched, prio); |
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blkcg = rq->elv.priv[0]; |
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ddcg_count(blkcg, dispatched, ioprio_class); |
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/* |
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* If the request needs its target zone locked, do it. |
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*/ |
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blk_req_zone_write_lock(rq); |
|
rq->rq_flags |= RQF_STARTED; |
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return rq; |
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} |
|
|
|
/* |
|
* Called from blk_mq_run_hw_queue() -> __blk_mq_sched_dispatch_requests(). |
|
* |
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* One confusing aspect here is that we get called for a specific |
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* hardware queue, but we may return a request that is for a |
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* 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) |
|
{ |
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struct deadline_data *dd = hctx->queue->elevator->elevator_data; |
|
const u64 now_ns = ktime_get_ns(); |
|
struct request *rq = NULL; |
|
enum dd_prio prio; |
|
|
|
spin_lock(&dd->lock); |
|
/* |
|
* Start with dispatching requests whose deadline expired more than |
|
* aging_expire jiffies ago. |
|
*/ |
|
for (prio = DD_BE_PRIO; prio <= DD_PRIO_MAX; prio++) { |
|
rq = __dd_dispatch_request(dd, &dd->per_prio[prio], now_ns - |
|
jiffies_to_nsecs(dd->aging_expire)); |
|
if (rq) |
|
goto unlock; |
|
} |
|
/* |
|
* Next, dispatch requests in priority order. Ignore lower priority |
|
* requests if any higher priority requests are pending. |
|
*/ |
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for (prio = 0; prio <= DD_PRIO_MAX; prio++) { |
|
rq = __dd_dispatch_request(dd, &dd->per_prio[prio], now_ns); |
|
if (rq || dd_queued(dd, prio)) |
|
break; |
|
} |
|
|
|
unlock: |
|
spin_unlock(&dd->lock); |
|
|
|
return rq; |
|
} |
|
|
|
/* |
|
* Called by __blk_mq_alloc_request(). The shallow_depth value set by this |
|
* function is used by __blk_mq_get_tag(). |
|
*/ |
|
static void dd_limit_depth(unsigned int op, struct blk_mq_alloc_data *data) |
|
{ |
|
struct deadline_data *dd = data->q->elevator->elevator_data; |
|
|
|
/* Do not throttle synchronous reads. */ |
|
if (op_is_sync(op) && !op_is_write(op)) |
|
return; |
|
|
|
/* |
|
* Throttle asynchronous requests and writes such that these requests |
|
* do not block the allocation of synchronous requests. |
|
*/ |
|
data->shallow_depth = dd->async_depth; |
|
} |
|
|
|
/* Called by blk_mq_update_nr_requests(). */ |
|
static void dd_depth_updated(struct blk_mq_hw_ctx *hctx) |
|
{ |
|
struct request_queue *q = hctx->queue; |
|
struct deadline_data *dd = q->elevator->elevator_data; |
|
struct blk_mq_tags *tags = hctx->sched_tags; |
|
|
|
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; |
|
dd->aging_expire = aging_expire; |
|
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; |
|
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); |
|
|
|
/* |
|
* 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); |
|
rq->elv.priv[0] = blkcg; |
|
|
|
if (blk_mq_sched_try_insert_merge(q, rq, &free)) { |
|
blk_mq_free_requests(&free); |
|
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_JIFFIES(deadline_aging_expire_show, dd->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->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_JIFFIES(deadline_aging_expire_store, &dd->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->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), |
|
DD_ATTR(aging_expire), |
|
__ATTR_NULL |
|
}; |
|
|
|
#ifdef CONFIG_BLK_DEBUG_FS |
|
#define DEADLINE_DEBUGFS_DDIR_ATTRS(prio, data_dir, name) \ |
|
static void *deadline_##name##_fifo_start(struct seq_file *m, \ |
|
loff_t *pos) \ |
|
__acquires(&dd->lock) \ |
|
{ \ |
|
struct request_queue *q = m->private; \ |
|
struct deadline_data *dd = q->elevator->elevator_data; \ |
|
struct dd_per_prio *per_prio = &dd->per_prio[prio]; \ |
|
\ |
|
spin_lock(&dd->lock); \ |
|
return seq_list_start(&per_prio->fifo_list[data_dir], *pos); \ |
|
} \ |
|
\ |
|
static void *deadline_##name##_fifo_next(struct seq_file *m, void *v, \ |
|
loff_t *pos) \ |
|
{ \ |
|
struct request_queue *q = m->private; \ |
|
struct deadline_data *dd = q->elevator->elevator_data; \ |
|
struct dd_per_prio *per_prio = &dd->per_prio[prio]; \ |
|
\ |
|
return seq_list_next(v, &per_prio->fifo_list[data_dir], pos); \ |
|
} \ |
|
\ |
|
static void deadline_##name##_fifo_stop(struct seq_file *m, void *v) \ |
|
__releases(&dd->lock) \ |
|
{ \ |
|
struct request_queue *q = m->private; \ |
|
struct deadline_data *dd = q->elevator->elevator_data; \ |
|
\ |
|
spin_unlock(&dd->lock); \ |
|
} \ |
|
\ |
|
static const struct seq_operations deadline_##name##_fifo_seq_ops = { \ |
|
.start = deadline_##name##_fifo_start, \ |
|
.next = deadline_##name##_fifo_next, \ |
|
.stop = deadline_##name##_fifo_stop, \ |
|
.show = blk_mq_debugfs_rq_show, \ |
|
}; \ |
|
\ |
|
static int deadline_##name##_next_rq_show(void *data, \ |
|
struct seq_file *m) \ |
|
{ \ |
|
struct request_queue *q = data; \ |
|
struct deadline_data *dd = q->elevator->elevator_data; \ |
|
struct dd_per_prio *per_prio = &dd->per_prio[prio]; \ |
|
struct request *rq = per_prio->next_rq[data_dir]; \ |
|
\ |
|
if (rq) \ |
|
__blk_mq_debugfs_rq_show(m, rq); \ |
|
return 0; \ |
|
} |
|
|
|
DEADLINE_DEBUGFS_DDIR_ATTRS(DD_RT_PRIO, DD_READ, read0); |
|
DEADLINE_DEBUGFS_DDIR_ATTRS(DD_RT_PRIO, DD_WRITE, write0); |
|
DEADLINE_DEBUGFS_DDIR_ATTRS(DD_BE_PRIO, DD_READ, read1); |
|
DEADLINE_DEBUGFS_DDIR_ATTRS(DD_BE_PRIO, DD_WRITE, write1); |
|
DEADLINE_DEBUGFS_DDIR_ATTRS(DD_IDLE_PRIO, DD_READ, read2); |
|
DEADLINE_DEBUGFS_DDIR_ATTRS(DD_IDLE_PRIO, DD_WRITE, write2); |
|
#undef DEADLINE_DEBUGFS_DDIR_ATTRS |
|
|
|
static int deadline_batching_show(void *data, struct seq_file *m) |
|
{ |
|
struct request_queue *q = data; |
|
struct deadline_data *dd = q->elevator->elevator_data; |
|
|
|
seq_printf(m, "%u\n", dd->batching); |
|
return 0; |
|
} |
|
|
|
static int deadline_starved_show(void *data, struct seq_file *m) |
|
{ |
|
struct request_queue *q = data; |
|
struct deadline_data *dd = q->elevator->elevator_data; |
|
|
|
seq_printf(m, "%u\n", dd->starved); |
|
return 0; |
|
} |
|
|
|
static int dd_async_depth_show(void *data, struct seq_file *m) |
|
{ |
|
struct request_queue *q = data; |
|
struct deadline_data *dd = q->elevator->elevator_data; |
|
|
|
seq_printf(m, "%u\n", dd->async_depth); |
|
return 0; |
|
} |
|
|
|
static int dd_queued_show(void *data, struct seq_file *m) |
|
{ |
|
struct request_queue *q = data; |
|
struct deadline_data *dd = q->elevator->elevator_data; |
|
|
|
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");
|
|
|