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author | Jens Axboe <axboe@kernel.dk> | 2018-10-12 10:14:46 -0600 |
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committer | Jens Axboe <axboe@kernel.dk> | 2018-11-07 13:42:32 -0700 |
commit | f382fb0bcef4c37dc049e9f6963e3baf204d815c (patch) | |
tree | dbfbe5689176a03ea1590497f965b40b2f8fd532 /block/deadline-iosched.c | |
parent | 404b8f5a03d840f74669fd55e26f8e3564cc2dd8 (diff) | |
download | linux-f382fb0bcef4c37dc049e9f6963e3baf204d815c.tar.bz2 |
block: remove legacy IO schedulers
Retain the deadline documentation, as that carries over to mq-deadline
as well.
Tested-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/deadline-iosched.c')
-rw-r--r-- | block/deadline-iosched.c | 560 |
1 files changed, 0 insertions, 560 deletions
diff --git a/block/deadline-iosched.c b/block/deadline-iosched.c deleted file mode 100644 index ef2f1f09e9b3..000000000000 --- a/block/deadline-iosched.c +++ /dev/null @@ -1,560 +0,0 @@ -/* - * Deadline i/o scheduler. - * - * Copyright (C) 2002 Jens Axboe <axboe@kernel.dk> - */ -#include <linux/kernel.h> -#include <linux/fs.h> -#include <linux/blkdev.h> -#include <linux/elevator.h> -#include <linux/bio.h> -#include <linux/module.h> -#include <linux/slab.h> -#include <linux/init.h> -#include <linux/compiler.h> -#include <linux/rbtree.h> - -/* - * See Documentation/block/deadline-iosched.txt - */ -static const int read_expire = HZ / 2; /* max time before a read is submitted. */ -static const int write_expire = 5 * HZ; /* ditto for writes, these limits are SOFT! */ -static const int writes_starved = 2; /* max times reads can starve a write */ -static const int fifo_batch = 16; /* # of sequential requests treated as one - by the above parameters. For throughput. */ - -struct deadline_data { - /* - * run time data - */ - - /* - * requests (deadline_rq s) are present on both sort_list and fifo_list - */ - struct rb_root sort_list[2]; - struct list_head fifo_list[2]; - - /* - * next in sort order. read, write or both are NULL - */ - struct request *next_rq[2]; - unsigned int batching; /* number of sequential requests made */ - unsigned int starved; /* times reads have starved writes */ - - /* - * settings that change how the i/o scheduler behaves - */ - int fifo_expire[2]; - int fifo_batch; - int writes_starved; - int front_merges; -}; - -static inline struct rb_root * -deadline_rb_root(struct deadline_data *dd, struct request *rq) -{ - return &dd->sort_list[rq_data_dir(rq)]; -} - -/* - * get the request after `rq' in sector-sorted order - */ -static inline struct request * -deadline_latter_request(struct request *rq) -{ - struct rb_node *node = rb_next(&rq->rb_node); - - if (node) - return rb_entry_rq(node); - - return NULL; -} - -static void -deadline_add_rq_rb(struct deadline_data *dd, struct request *rq) -{ - struct rb_root *root = deadline_rb_root(dd, rq); - - elv_rb_add(root, rq); -} - -static inline void -deadline_del_rq_rb(struct deadline_data *dd, struct request *rq) -{ - const int data_dir = rq_data_dir(rq); - - if (dd->next_rq[data_dir] == rq) - dd->next_rq[data_dir] = deadline_latter_request(rq); - - elv_rb_del(deadline_rb_root(dd, rq), rq); -} - -/* - * add rq to rbtree and fifo - */ -static void -deadline_add_request(struct request_queue *q, struct request *rq) -{ - struct deadline_data *dd = q->elevator->elevator_data; - const int data_dir = rq_data_dir(rq); - - /* - * 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); - - deadline_add_rq_rb(dd, rq); - - /* - * set expire time and add to fifo list - */ - rq->fifo_time = jiffies + dd->fifo_expire[data_dir]; - list_add_tail(&rq->queuelist, &dd->fifo_list[data_dir]); -} - -/* - * remove rq from rbtree and fifo. - */ -static void deadline_remove_request(struct request_queue *q, struct request *rq) -{ - struct deadline_data *dd = q->elevator->elevator_data; - - rq_fifo_clear(rq); - deadline_del_rq_rb(dd, rq); -} - -static enum elv_merge -deadline_merge(struct request_queue *q, struct request **req, struct bio *bio) -{ - struct deadline_data *dd = q->elevator->elevator_data; - struct request *__rq; - - /* - * check for front merge - */ - if (dd->front_merges) { - sector_t sector = bio_end_sector(bio); - - __rq = elv_rb_find(&dd->sort_list[bio_data_dir(bio)], sector); - if (__rq) { - BUG_ON(sector != blk_rq_pos(__rq)); - - if (elv_bio_merge_ok(__rq, bio)) { - *req = __rq; - return ELEVATOR_FRONT_MERGE; - } - } - } - - return ELEVATOR_NO_MERGE; -} - -static void deadline_merged_request(struct request_queue *q, - struct request *req, enum elv_merge type) -{ - struct deadline_data *dd = q->elevator->elevator_data; - - /* - * if the merge was a front merge, we need to reposition request - */ - if (type == ELEVATOR_FRONT_MERGE) { - elv_rb_del(deadline_rb_root(dd, req), req); - deadline_add_rq_rb(dd, req); - } -} - -static void -deadline_merged_requests(struct request_queue *q, struct request *req, - struct request *next) -{ - /* - * if next expires before rq, assign its expire time to rq - * and move into next position (next will be deleted) in fifo - */ - if (!list_empty(&req->queuelist) && !list_empty(&next->queuelist)) { - if (time_before((unsigned long)next->fifo_time, - (unsigned long)req->fifo_time)) { - list_move(&req->queuelist, &next->queuelist); - req->fifo_time = next->fifo_time; - } - } - - /* - * kill knowledge of next, this one is a goner - */ - deadline_remove_request(q, next); -} - -/* - * move request from sort list to dispatch queue. - */ -static inline void -deadline_move_to_dispatch(struct deadline_data *dd, struct request *rq) -{ - struct request_queue *q = rq->q; - - /* - * For a zoned block device, write requests must write lock their - * target zone. - */ - blk_req_zone_write_lock(rq); - - deadline_remove_request(q, rq); - elv_dispatch_add_tail(q, rq); -} - -/* - * move an entry to dispatch queue - */ -static void -deadline_move_request(struct deadline_data *dd, struct request *rq) -{ - const int data_dir = rq_data_dir(rq); - - dd->next_rq[READ] = NULL; - dd->next_rq[WRITE] = NULL; - dd->next_rq[data_dir] = deadline_latter_request(rq); - - /* - * take it off the sort and fifo list, move - * to dispatch queue - */ - deadline_move_to_dispatch(dd, rq); -} - -/* - * deadline_check_fifo returns 0 if there are no expired requests on the fifo, - * 1 otherwise. Requires !list_empty(&dd->fifo_list[data_dir]) - */ -static inline int deadline_check_fifo(struct deadline_data *dd, int ddir) -{ - struct request *rq = rq_entry_fifo(dd->fifo_list[ddir].next); - - /* - * rq is expired! - */ - if (time_after_eq(jiffies, (unsigned long)rq->fifo_time)) - return 1; - - return 0; -} - -/* - * For the specified data direction, return the next request to dispatch using - * arrival ordered lists. - */ -static struct request * -deadline_fifo_request(struct deadline_data *dd, int data_dir) -{ - struct request *rq; - - if (WARN_ON_ONCE(data_dir != READ && data_dir != WRITE)) - return NULL; - - if (list_empty(&dd->fifo_list[data_dir])) - return NULL; - - rq = rq_entry_fifo(dd->fifo_list[data_dir].next); - if (data_dir == READ || !blk_queue_is_zoned(rq->q)) - return rq; - - /* - * Look for a write request that can be dispatched, that is one with - * an unlocked target zone. - */ - list_for_each_entry(rq, &dd->fifo_list[WRITE], queuelist) { - if (blk_req_can_dispatch_to_zone(rq)) - return rq; - } - - return NULL; -} - -/* - * For the specified data direction, return the next request to dispatch using - * sector position sorted lists. - */ -static struct request * -deadline_next_request(struct deadline_data *dd, int data_dir) -{ - struct request *rq; - - if (WARN_ON_ONCE(data_dir != READ && data_dir != WRITE)) - return NULL; - - rq = dd->next_rq[data_dir]; - if (!rq) - return NULL; - - if (data_dir == READ || !blk_queue_is_zoned(rq->q)) - return rq; - - /* - * Look for a write request that can be dispatched, that is one with - * an unlocked target zone. - */ - while (rq) { - if (blk_req_can_dispatch_to_zone(rq)) - return rq; - rq = deadline_latter_request(rq); - } - - return NULL; -} - -/* - * deadline_dispatch_requests selects the best request according to - * read/write expire, fifo_batch, etc - */ -static int deadline_dispatch_requests(struct request_queue *q, int force) -{ - struct deadline_data *dd = q->elevator->elevator_data; - const int reads = !list_empty(&dd->fifo_list[READ]); - const int writes = !list_empty(&dd->fifo_list[WRITE]); - struct request *rq, *next_rq; - int data_dir; - - /* - * batches are currently reads XOR writes - */ - rq = deadline_next_request(dd, WRITE); - if (!rq) - rq = deadline_next_request(dd, READ); - - if (rq && dd->batching < dd->fifo_batch) - /* we have a next request are still entitled to batch */ - goto dispatch_request; - - /* - * at this point we are not running a batch. select the appropriate - * data direction (read / write) - */ - - if (reads) { - BUG_ON(RB_EMPTY_ROOT(&dd->sort_list[READ])); - - if (deadline_fifo_request(dd, WRITE) && - (dd->starved++ >= dd->writes_starved)) - goto dispatch_writes; - - data_dir = READ; - - goto dispatch_find_request; - } - - /* - * there are either no reads or writes have been starved - */ - - if (writes) { -dispatch_writes: - BUG_ON(RB_EMPTY_ROOT(&dd->sort_list[WRITE])); - - dd->starved = 0; - - data_dir = WRITE; - - goto dispatch_find_request; - } - - return 0; - -dispatch_find_request: - /* - * we are not running a batch, find best request for selected data_dir - */ - next_rq = deadline_next_request(dd, data_dir); - if (deadline_check_fifo(dd, data_dir) || !next_rq) { - /* - * A deadline has expired, the last request was in the other - * direction, or we have run out of higher-sectored requests. - * Start again from the request with the earliest expiry time. - */ - rq = deadline_fifo_request(dd, data_dir); - } else { - /* - * The last req was the same dir and we have a next request in - * sort order. No expired requests so continue on from here. - */ - rq = next_rq; - } - - /* - * For a zoned block device, if we only have writes queued and none of - * them can be dispatched, rq will be NULL. - */ - if (!rq) - return 0; - - dd->batching = 0; - -dispatch_request: - /* - * rq is the selected appropriate request. - */ - dd->batching++; - deadline_move_request(dd, rq); - - return 1; -} - -/* - * For zoned block devices, write unlock the target zone of completed - * write requests. - */ -static void -deadline_completed_request(struct request_queue *q, struct request *rq) -{ - blk_req_zone_write_unlock(rq); -} - -static void deadline_exit_queue(struct elevator_queue *e) -{ - struct deadline_data *dd = e->elevator_data; - - BUG_ON(!list_empty(&dd->fifo_list[READ])); - BUG_ON(!list_empty(&dd->fifo_list[WRITE])); - - kfree(dd); -} - -/* - * initialize elevator private data (deadline_data). - */ -static int deadline_init_queue(struct request_queue *q, struct elevator_type *e) -{ - struct deadline_data *dd; - struct elevator_queue *eq; - - eq = elevator_alloc(q, e); - if (!eq) - return -ENOMEM; - - dd = kzalloc_node(sizeof(*dd), GFP_KERNEL, q->node); - if (!dd) { - kobject_put(&eq->kobj); - return -ENOMEM; - } - eq->elevator_data = dd; - - INIT_LIST_HEAD(&dd->fifo_list[READ]); - INIT_LIST_HEAD(&dd->fifo_list[WRITE]); - dd->sort_list[READ] = RB_ROOT; - dd->sort_list[WRITE] = RB_ROOT; - dd->fifo_expire[READ] = read_expire; - dd->fifo_expire[WRITE] = write_expire; - dd->writes_starved = writes_starved; - dd->front_merges = 1; - dd->fifo_batch = fifo_batch; - - spin_lock_irq(q->queue_lock); - q->elevator = eq; - spin_unlock_irq(q->queue_lock); - return 0; -} - -/* - * sysfs parts below - */ - -static ssize_t -deadline_var_show(int var, char *page) -{ - return sprintf(page, "%d\n", var); -} - -static void -deadline_var_store(int *var, const char *page) -{ - char *p = (char *) page; - - *var = simple_strtol(p, &p, 10); -} - -#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \ -static ssize_t __FUNC(struct elevator_queue *e, char *page) \ -{ \ - struct deadline_data *dd = e->elevator_data; \ - int __data = __VAR; \ - if (__CONV) \ - __data = jiffies_to_msecs(__data); \ - return deadline_var_show(__data, (page)); \ -} -SHOW_FUNCTION(deadline_read_expire_show, dd->fifo_expire[READ], 1); -SHOW_FUNCTION(deadline_write_expire_show, dd->fifo_expire[WRITE], 1); -SHOW_FUNCTION(deadline_writes_starved_show, dd->writes_starved, 0); -SHOW_FUNCTION(deadline_front_merges_show, dd->front_merges, 0); -SHOW_FUNCTION(deadline_fifo_batch_show, dd->fifo_batch, 0); -#undef SHOW_FUNCTION - -#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; \ - deadline_var_store(&__data, (page)); \ - if (__data < (MIN)) \ - __data = (MIN); \ - else if (__data > (MAX)) \ - __data = (MAX); \ - if (__CONV) \ - *(__PTR) = msecs_to_jiffies(__data); \ - else \ - *(__PTR) = __data; \ - return count; \ -} -STORE_FUNCTION(deadline_read_expire_store, &dd->fifo_expire[READ], 0, INT_MAX, 1); -STORE_FUNCTION(deadline_write_expire_store, &dd->fifo_expire[WRITE], 0, INT_MAX, 1); -STORE_FUNCTION(deadline_writes_starved_store, &dd->writes_starved, INT_MIN, INT_MAX, 0); -STORE_FUNCTION(deadline_front_merges_store, &dd->front_merges, 0, 1, 0); -STORE_FUNCTION(deadline_fifo_batch_store, &dd->fifo_batch, 0, INT_MAX, 0); -#undef STORE_FUNCTION - -#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(fifo_batch), - __ATTR_NULL -}; - -static struct elevator_type iosched_deadline = { - .ops.sq = { - .elevator_merge_fn = deadline_merge, - .elevator_merged_fn = deadline_merged_request, - .elevator_merge_req_fn = deadline_merged_requests, - .elevator_dispatch_fn = deadline_dispatch_requests, - .elevator_completed_req_fn = deadline_completed_request, - .elevator_add_req_fn = deadline_add_request, - .elevator_former_req_fn = elv_rb_former_request, - .elevator_latter_req_fn = elv_rb_latter_request, - .elevator_init_fn = deadline_init_queue, - .elevator_exit_fn = deadline_exit_queue, - }, - - .elevator_attrs = deadline_attrs, - .elevator_name = "deadline", - .elevator_owner = THIS_MODULE, -}; - -static int __init deadline_init(void) -{ - return elv_register(&iosched_deadline); -} - -static void __exit deadline_exit(void) -{ - elv_unregister(&iosched_deadline); -} - -module_init(deadline_init); -module_exit(deadline_exit); - -MODULE_AUTHOR("Jens Axboe"); -MODULE_LICENSE("GPL"); -MODULE_DESCRIPTION("deadline IO scheduler"); |