2005-04-17 06:20:36 +08:00
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/*
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* linux/drivers/block/deadline-iosched.c
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*
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* Deadline i/o scheduler.
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*
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* Copyright (C) 2002 Jens Axboe <axboe@suse.de>
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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/elevator.h>
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#include <linux/bio.h>
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#include <linux/config.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/hash.h>
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#include <linux/rbtree.h>
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/*
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* See Documentation/block/deadline-iosched.txt
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*/
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static int read_expire = HZ / 2; /* max time before a read is submitted. */
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static int write_expire = 5 * HZ; /* ditto for writes, these limits are SOFT! */
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static int writes_starved = 2; /* max times reads can starve a write */
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static int fifo_batch = 16; /* # of sequential requests treated as one
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by the above parameters. For throughput. */
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static const int deadline_hash_shift = 5;
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#define DL_HASH_BLOCK(sec) ((sec) >> 3)
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#define DL_HASH_FN(sec) (hash_long(DL_HASH_BLOCK((sec)), deadline_hash_shift))
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#define DL_HASH_ENTRIES (1 << deadline_hash_shift)
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#define rq_hash_key(rq) ((rq)->sector + (rq)->nr_sectors)
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#define list_entry_hash(ptr) list_entry((ptr), struct deadline_rq, hash)
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#define ON_HASH(drq) (drq)->on_hash
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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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* requests (deadline_rq s) are present on both sort_list and fifo_list
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*/
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struct rb_root sort_list[2];
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struct list_head fifo_list[2];
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/*
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* next in sort order. read, write or both are NULL
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*/
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struct deadline_rq *next_drq[2];
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struct list_head *dispatch; /* driver dispatch queue */
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struct list_head *hash; /* request hash */
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unsigned int batching; /* number of sequential requests made */
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sector_t last_sector; /* head position */
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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[2];
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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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mempool_t *drq_pool;
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};
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/*
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* pre-request data.
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*/
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struct deadline_rq {
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/*
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* rbtree index, key is the starting offset
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*/
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struct rb_node rb_node;
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sector_t rb_key;
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struct request *request;
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/*
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* request hash, key is the ending offset (for back merge lookup)
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*/
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struct list_head hash;
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char on_hash;
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/*
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* expire fifo
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*/
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struct list_head fifo;
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unsigned long expires;
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};
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static void deadline_move_request(struct deadline_data *dd, struct deadline_rq *drq);
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static kmem_cache_t *drq_pool;
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#define RQ_DATA(rq) ((struct deadline_rq *) (rq)->elevator_private)
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/*
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* the back merge hash support functions
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*/
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static inline void __deadline_del_drq_hash(struct deadline_rq *drq)
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{
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drq->on_hash = 0;
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list_del_init(&drq->hash);
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}
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static inline void deadline_del_drq_hash(struct deadline_rq *drq)
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{
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if (ON_HASH(drq))
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__deadline_del_drq_hash(drq);
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}
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static void
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deadline_remove_merge_hints(request_queue_t *q, struct deadline_rq *drq)
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{
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deadline_del_drq_hash(drq);
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if (q->last_merge == drq->request)
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q->last_merge = NULL;
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}
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static inline void
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deadline_add_drq_hash(struct deadline_data *dd, struct deadline_rq *drq)
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{
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struct request *rq = drq->request;
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BUG_ON(ON_HASH(drq));
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drq->on_hash = 1;
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list_add(&drq->hash, &dd->hash[DL_HASH_FN(rq_hash_key(rq))]);
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}
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/*
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* move hot entry to front of chain
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*/
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static inline void
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deadline_hot_drq_hash(struct deadline_data *dd, struct deadline_rq *drq)
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{
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struct request *rq = drq->request;
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struct list_head *head = &dd->hash[DL_HASH_FN(rq_hash_key(rq))];
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if (ON_HASH(drq) && drq->hash.prev != head) {
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list_del(&drq->hash);
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list_add(&drq->hash, head);
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}
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}
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static struct request *
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deadline_find_drq_hash(struct deadline_data *dd, sector_t offset)
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{
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struct list_head *hash_list = &dd->hash[DL_HASH_FN(offset)];
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struct list_head *entry, *next = hash_list->next;
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while ((entry = next) != hash_list) {
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struct deadline_rq *drq = list_entry_hash(entry);
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struct request *__rq = drq->request;
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next = entry->next;
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BUG_ON(!ON_HASH(drq));
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if (!rq_mergeable(__rq)) {
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__deadline_del_drq_hash(drq);
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continue;
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}
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if (rq_hash_key(__rq) == offset)
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return __rq;
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}
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return NULL;
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}
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/*
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* rb tree support functions
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*/
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#define RB_NONE (2)
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#define RB_EMPTY(root) ((root)->rb_node == NULL)
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#define ON_RB(node) ((node)->rb_color != RB_NONE)
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#define RB_CLEAR(node) ((node)->rb_color = RB_NONE)
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#define rb_entry_drq(node) rb_entry((node), struct deadline_rq, rb_node)
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#define DRQ_RB_ROOT(dd, drq) (&(dd)->sort_list[rq_data_dir((drq)->request)])
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#define rq_rb_key(rq) (rq)->sector
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static struct deadline_rq *
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__deadline_add_drq_rb(struct deadline_data *dd, struct deadline_rq *drq)
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{
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struct rb_node **p = &DRQ_RB_ROOT(dd, drq)->rb_node;
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struct rb_node *parent = NULL;
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struct deadline_rq *__drq;
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while (*p) {
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parent = *p;
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__drq = rb_entry_drq(parent);
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if (drq->rb_key < __drq->rb_key)
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p = &(*p)->rb_left;
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else if (drq->rb_key > __drq->rb_key)
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p = &(*p)->rb_right;
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else
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return __drq;
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}
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rb_link_node(&drq->rb_node, parent, p);
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return NULL;
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}
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static void
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deadline_add_drq_rb(struct deadline_data *dd, struct deadline_rq *drq)
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{
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struct deadline_rq *__alias;
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drq->rb_key = rq_rb_key(drq->request);
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retry:
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__alias = __deadline_add_drq_rb(dd, drq);
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if (!__alias) {
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rb_insert_color(&drq->rb_node, DRQ_RB_ROOT(dd, drq));
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return;
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}
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deadline_move_request(dd, __alias);
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goto retry;
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}
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static inline void
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deadline_del_drq_rb(struct deadline_data *dd, struct deadline_rq *drq)
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{
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const int data_dir = rq_data_dir(drq->request);
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if (dd->next_drq[data_dir] == drq) {
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struct rb_node *rbnext = rb_next(&drq->rb_node);
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dd->next_drq[data_dir] = NULL;
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if (rbnext)
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dd->next_drq[data_dir] = rb_entry_drq(rbnext);
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}
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if (ON_RB(&drq->rb_node)) {
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rb_erase(&drq->rb_node, DRQ_RB_ROOT(dd, drq));
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RB_CLEAR(&drq->rb_node);
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}
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}
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static struct request *
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deadline_find_drq_rb(struct deadline_data *dd, sector_t sector, int data_dir)
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{
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struct rb_node *n = dd->sort_list[data_dir].rb_node;
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struct deadline_rq *drq;
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while (n) {
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drq = rb_entry_drq(n);
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if (sector < drq->rb_key)
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n = n->rb_left;
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else if (sector > drq->rb_key)
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n = n->rb_right;
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else
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return drq->request;
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}
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return NULL;
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}
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/*
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* deadline_find_first_drq finds the first (lowest sector numbered) request
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* for the specified data_dir. Used to sweep back to the start of the disk
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* (1-way elevator) after we process the last (highest sector) request.
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*/
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static struct deadline_rq *
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deadline_find_first_drq(struct deadline_data *dd, int data_dir)
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{
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struct rb_node *n = dd->sort_list[data_dir].rb_node;
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for (;;) {
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if (n->rb_left == NULL)
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return rb_entry_drq(n);
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n = n->rb_left;
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}
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}
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/*
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* add drq to rbtree and fifo
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*/
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static inline void
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deadline_add_request(struct request_queue *q, struct request *rq)
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{
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struct deadline_data *dd = q->elevator->elevator_data;
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struct deadline_rq *drq = RQ_DATA(rq);
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const int data_dir = rq_data_dir(drq->request);
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deadline_add_drq_rb(dd, drq);
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/*
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* set expire time (only used for reads) and add to fifo list
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*/
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drq->expires = jiffies + dd->fifo_expire[data_dir];
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list_add_tail(&drq->fifo, &dd->fifo_list[data_dir]);
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if (rq_mergeable(rq)) {
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deadline_add_drq_hash(dd, drq);
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if (!q->last_merge)
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q->last_merge = rq;
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}
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}
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/*
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* remove rq from rbtree, fifo, and hash
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*/
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static void deadline_remove_request(request_queue_t *q, struct request *rq)
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{
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struct deadline_rq *drq = RQ_DATA(rq);
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if (drq) {
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struct deadline_data *dd = q->elevator->elevator_data;
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list_del_init(&drq->fifo);
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deadline_remove_merge_hints(q, drq);
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deadline_del_drq_rb(dd, drq);
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}
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}
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static int
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deadline_merge(request_queue_t *q, struct request **req, struct bio *bio)
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{
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struct deadline_data *dd = q->elevator->elevator_data;
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struct request *__rq;
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int ret;
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/*
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* try last_merge to avoid going to hash
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*/
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ret = elv_try_last_merge(q, bio);
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if (ret != ELEVATOR_NO_MERGE) {
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__rq = q->last_merge;
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goto out_insert;
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}
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/*
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* see if the merge hash can satisfy a back merge
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*/
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__rq = deadline_find_drq_hash(dd, bio->bi_sector);
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if (__rq) {
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BUG_ON(__rq->sector + __rq->nr_sectors != bio->bi_sector);
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if (elv_rq_merge_ok(__rq, bio)) {
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ret = ELEVATOR_BACK_MERGE;
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goto out;
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}
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}
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/*
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* check for front merge
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*/
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if (dd->front_merges) {
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sector_t rb_key = bio->bi_sector + bio_sectors(bio);
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__rq = deadline_find_drq_rb(dd, rb_key, bio_data_dir(bio));
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if (__rq) {
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BUG_ON(rb_key != rq_rb_key(__rq));
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if (elv_rq_merge_ok(__rq, bio)) {
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ret = ELEVATOR_FRONT_MERGE;
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goto out;
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}
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}
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}
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return ELEVATOR_NO_MERGE;
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out:
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q->last_merge = __rq;
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out_insert:
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if (ret)
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deadline_hot_drq_hash(dd, RQ_DATA(__rq));
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*req = __rq;
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return ret;
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}
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|
|
static void deadline_merged_request(request_queue_t *q, struct request *req)
|
|
|
|
{
|
|
|
|
struct deadline_data *dd = q->elevator->elevator_data;
|
|
|
|
struct deadline_rq *drq = RQ_DATA(req);
|
|
|
|
|
|
|
|
/*
|
|
|
|
* hash always needs to be repositioned, key is end sector
|
|
|
|
*/
|
|
|
|
deadline_del_drq_hash(drq);
|
|
|
|
deadline_add_drq_hash(dd, drq);
|
|
|
|
|
|
|
|
/*
|
|
|
|
* if the merge was a front merge, we need to reposition request
|
|
|
|
*/
|
|
|
|
if (rq_rb_key(req) != drq->rb_key) {
|
|
|
|
deadline_del_drq_rb(dd, drq);
|
|
|
|
deadline_add_drq_rb(dd, drq);
|
|
|
|
}
|
|
|
|
|
|
|
|
q->last_merge = req;
|
|
|
|
}
|
|
|
|
|
|
|
|
static void
|
|
|
|
deadline_merged_requests(request_queue_t *q, struct request *req,
|
|
|
|
struct request *next)
|
|
|
|
{
|
|
|
|
struct deadline_data *dd = q->elevator->elevator_data;
|
|
|
|
struct deadline_rq *drq = RQ_DATA(req);
|
|
|
|
struct deadline_rq *dnext = RQ_DATA(next);
|
|
|
|
|
|
|
|
BUG_ON(!drq);
|
|
|
|
BUG_ON(!dnext);
|
|
|
|
|
|
|
|
/*
|
|
|
|
* reposition drq (this is the merged request) in hash, and in rbtree
|
|
|
|
* in case of a front merge
|
|
|
|
*/
|
|
|
|
deadline_del_drq_hash(drq);
|
|
|
|
deadline_add_drq_hash(dd, drq);
|
|
|
|
|
|
|
|
if (rq_rb_key(req) != drq->rb_key) {
|
|
|
|
deadline_del_drq_rb(dd, drq);
|
|
|
|
deadline_add_drq_rb(dd, drq);
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* if dnext expires before drq, assign its expire time to drq
|
|
|
|
* and move into dnext position (dnext will be deleted) in fifo
|
|
|
|
*/
|
|
|
|
if (!list_empty(&drq->fifo) && !list_empty(&dnext->fifo)) {
|
|
|
|
if (time_before(dnext->expires, drq->expires)) {
|
|
|
|
list_move(&drq->fifo, &dnext->fifo);
|
|
|
|
drq->expires = dnext->expires;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* 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 deadline_rq *drq)
|
|
|
|
{
|
|
|
|
request_queue_t *q = drq->request->q;
|
|
|
|
|
|
|
|
deadline_remove_request(q, drq->request);
|
|
|
|
list_add_tail(&drq->request->queuelist, dd->dispatch);
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* move an entry to dispatch queue
|
|
|
|
*/
|
|
|
|
static void
|
|
|
|
deadline_move_request(struct deadline_data *dd, struct deadline_rq *drq)
|
|
|
|
{
|
|
|
|
const int data_dir = rq_data_dir(drq->request);
|
|
|
|
struct rb_node *rbnext = rb_next(&drq->rb_node);
|
|
|
|
|
|
|
|
dd->next_drq[READ] = NULL;
|
|
|
|
dd->next_drq[WRITE] = NULL;
|
|
|
|
|
|
|
|
if (rbnext)
|
|
|
|
dd->next_drq[data_dir] = rb_entry_drq(rbnext);
|
|
|
|
|
|
|
|
dd->last_sector = drq->request->sector + drq->request->nr_sectors;
|
|
|
|
|
|
|
|
/*
|
|
|
|
* take it off the sort and fifo list, move
|
|
|
|
* to dispatch queue
|
|
|
|
*/
|
|
|
|
deadline_move_to_dispatch(dd, drq);
|
|
|
|
}
|
|
|
|
|
|
|
|
#define list_entry_fifo(ptr) list_entry((ptr), struct deadline_rq, fifo)
|
|
|
|
|
|
|
|
/*
|
|
|
|
* deadline_check_fifo returns 0 if there are no expired reads 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 deadline_rq *drq = list_entry_fifo(dd->fifo_list[ddir].next);
|
|
|
|
|
|
|
|
/*
|
|
|
|
* drq is expired!
|
|
|
|
*/
|
|
|
|
if (time_after(jiffies, drq->expires))
|
|
|
|
return 1;
|
|
|
|
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* deadline_dispatch_requests selects the best request according to
|
|
|
|
* read/write expire, fifo_batch, etc
|
|
|
|
*/
|
|
|
|
static int deadline_dispatch_requests(struct deadline_data *dd)
|
|
|
|
{
|
|
|
|
const int reads = !list_empty(&dd->fifo_list[READ]);
|
|
|
|
const int writes = !list_empty(&dd->fifo_list[WRITE]);
|
|
|
|
struct deadline_rq *drq;
|
|
|
|
int data_dir, other_dir;
|
|
|
|
|
|
|
|
/*
|
|
|
|
* batches are currently reads XOR writes
|
|
|
|
*/
|
|
|
|
drq = NULL;
|
|
|
|
|
|
|
|
if (dd->next_drq[READ])
|
|
|
|
drq = dd->next_drq[READ];
|
|
|
|
|
|
|
|
if (dd->next_drq[WRITE])
|
|
|
|
drq = dd->next_drq[WRITE];
|
|
|
|
|
|
|
|
if (drq) {
|
|
|
|
/* we have a "next request" */
|
|
|
|
|
|
|
|
if (dd->last_sector != drq->request->sector)
|
|
|
|
/* end the batch on a non sequential request */
|
|
|
|
dd->batching += dd->fifo_batch;
|
|
|
|
|
|
|
|
if (dd->batching < dd->fifo_batch)
|
|
|
|
/* we 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(&dd->sort_list[READ]));
|
|
|
|
|
|
|
|
if (writes && (dd->starved++ >= dd->writes_starved))
|
|
|
|
goto dispatch_writes;
|
|
|
|
|
|
|
|
data_dir = READ;
|
|
|
|
other_dir = WRITE;
|
|
|
|
|
|
|
|
goto dispatch_find_request;
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* there are either no reads or writes have been starved
|
|
|
|
*/
|
|
|
|
|
|
|
|
if (writes) {
|
|
|
|
dispatch_writes:
|
|
|
|
BUG_ON(RB_EMPTY(&dd->sort_list[WRITE]));
|
|
|
|
|
|
|
|
dd->starved = 0;
|
|
|
|
|
|
|
|
data_dir = WRITE;
|
|
|
|
other_dir = READ;
|
|
|
|
|
|
|
|
goto dispatch_find_request;
|
|
|
|
}
|
|
|
|
|
|
|
|
return 0;
|
|
|
|
|
|
|
|
dispatch_find_request:
|
|
|
|
/*
|
|
|
|
* we are not running a batch, find best request for selected data_dir
|
|
|
|
*/
|
|
|
|
if (deadline_check_fifo(dd, data_dir)) {
|
|
|
|
/* An expired request exists - satisfy it */
|
|
|
|
dd->batching = 0;
|
|
|
|
drq = list_entry_fifo(dd->fifo_list[data_dir].next);
|
|
|
|
|
|
|
|
} else if (dd->next_drq[data_dir]) {
|
|
|
|
/*
|
|
|
|
* The last req was the same dir and we have a next request in
|
|
|
|
* sort order. No expired requests so continue on from here.
|
|
|
|
*/
|
|
|
|
drq = dd->next_drq[data_dir];
|
|
|
|
} else {
|
|
|
|
/*
|
|
|
|
* The last req was the other direction or we have run out of
|
|
|
|
* higher-sectored requests. Go back to the lowest sectored
|
|
|
|
* request (1 way elevator) and start a new batch.
|
|
|
|
*/
|
|
|
|
dd->batching = 0;
|
|
|
|
drq = deadline_find_first_drq(dd, data_dir);
|
|
|
|
}
|
|
|
|
|
|
|
|
dispatch_request:
|
|
|
|
/*
|
|
|
|
* drq is the selected appropriate request.
|
|
|
|
*/
|
|
|
|
dd->batching++;
|
|
|
|
deadline_move_request(dd, drq);
|
|
|
|
|
|
|
|
return 1;
|
|
|
|
}
|
|
|
|
|
|
|
|
static struct request *deadline_next_request(request_queue_t *q)
|
|
|
|
{
|
|
|
|
struct deadline_data *dd = q->elevator->elevator_data;
|
|
|
|
struct request *rq;
|
|
|
|
|
|
|
|
/*
|
|
|
|
* if there are still requests on the dispatch queue, grab the first one
|
|
|
|
*/
|
|
|
|
if (!list_empty(dd->dispatch)) {
|
|
|
|
dispatch:
|
|
|
|
rq = list_entry_rq(dd->dispatch->next);
|
|
|
|
return rq;
|
|
|
|
}
|
|
|
|
|
|
|
|
if (deadline_dispatch_requests(dd))
|
|
|
|
goto dispatch;
|
|
|
|
|
|
|
|
return NULL;
|
|
|
|
}
|
|
|
|
|
|
|
|
static void
|
|
|
|
deadline_insert_request(request_queue_t *q, struct request *rq, int where)
|
|
|
|
{
|
|
|
|
struct deadline_data *dd = q->elevator->elevator_data;
|
|
|
|
|
|
|
|
/* barriers must flush the reorder queue */
|
|
|
|
if (unlikely(rq->flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER)
|
|
|
|
&& where == ELEVATOR_INSERT_SORT))
|
|
|
|
where = ELEVATOR_INSERT_BACK;
|
|
|
|
|
|
|
|
switch (where) {
|
|
|
|
case ELEVATOR_INSERT_BACK:
|
|
|
|
while (deadline_dispatch_requests(dd))
|
|
|
|
;
|
|
|
|
list_add_tail(&rq->queuelist, dd->dispatch);
|
|
|
|
break;
|
|
|
|
case ELEVATOR_INSERT_FRONT:
|
|
|
|
list_add(&rq->queuelist, dd->dispatch);
|
|
|
|
break;
|
|
|
|
case ELEVATOR_INSERT_SORT:
|
|
|
|
BUG_ON(!blk_fs_request(rq));
|
|
|
|
deadline_add_request(q, rq);
|
|
|
|
break;
|
|
|
|
default:
|
|
|
|
printk("%s: bad insert point %d\n", __FUNCTION__,where);
|
|
|
|
return;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
static int deadline_queue_empty(request_queue_t *q)
|
|
|
|
{
|
|
|
|
struct deadline_data *dd = q->elevator->elevator_data;
|
|
|
|
|
|
|
|
if (!list_empty(&dd->fifo_list[WRITE])
|
|
|
|
|| !list_empty(&dd->fifo_list[READ])
|
|
|
|
|| !list_empty(dd->dispatch))
|
|
|
|
return 0;
|
|
|
|
|
|
|
|
return 1;
|
|
|
|
}
|
|
|
|
|
|
|
|
static struct request *
|
|
|
|
deadline_former_request(request_queue_t *q, struct request *rq)
|
|
|
|
{
|
|
|
|
struct deadline_rq *drq = RQ_DATA(rq);
|
|
|
|
struct rb_node *rbprev = rb_prev(&drq->rb_node);
|
|
|
|
|
|
|
|
if (rbprev)
|
|
|
|
return rb_entry_drq(rbprev)->request;
|
|
|
|
|
|
|
|
return NULL;
|
|
|
|
}
|
|
|
|
|
|
|
|
static struct request *
|
|
|
|
deadline_latter_request(request_queue_t *q, struct request *rq)
|
|
|
|
{
|
|
|
|
struct deadline_rq *drq = RQ_DATA(rq);
|
|
|
|
struct rb_node *rbnext = rb_next(&drq->rb_node);
|
|
|
|
|
|
|
|
if (rbnext)
|
|
|
|
return rb_entry_drq(rbnext)->request;
|
|
|
|
|
|
|
|
return NULL;
|
|
|
|
}
|
|
|
|
|
|
|
|
static void deadline_exit_queue(elevator_t *e)
|
|
|
|
{
|
|
|
|
struct deadline_data *dd = e->elevator_data;
|
|
|
|
|
|
|
|
BUG_ON(!list_empty(&dd->fifo_list[READ]));
|
|
|
|
BUG_ON(!list_empty(&dd->fifo_list[WRITE]));
|
|
|
|
|
|
|
|
mempool_destroy(dd->drq_pool);
|
|
|
|
kfree(dd->hash);
|
|
|
|
kfree(dd);
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* initialize elevator private data (deadline_data), and alloc a drq for
|
|
|
|
* each request on the free lists
|
|
|
|
*/
|
|
|
|
static int deadline_init_queue(request_queue_t *q, elevator_t *e)
|
|
|
|
{
|
|
|
|
struct deadline_data *dd;
|
|
|
|
int i;
|
|
|
|
|
|
|
|
if (!drq_pool)
|
|
|
|
return -ENOMEM;
|
|
|
|
|
|
|
|
dd = kmalloc(sizeof(*dd), GFP_KERNEL);
|
|
|
|
if (!dd)
|
|
|
|
return -ENOMEM;
|
|
|
|
memset(dd, 0, sizeof(*dd));
|
|
|
|
|
|
|
|
dd->hash = kmalloc(sizeof(struct list_head)*DL_HASH_ENTRIES,GFP_KERNEL);
|
|
|
|
if (!dd->hash) {
|
|
|
|
kfree(dd);
|
|
|
|
return -ENOMEM;
|
|
|
|
}
|
|
|
|
|
|
|
|
dd->drq_pool = mempool_create(BLKDEV_MIN_RQ, mempool_alloc_slab, mempool_free_slab, drq_pool);
|
|
|
|
if (!dd->drq_pool) {
|
|
|
|
kfree(dd->hash);
|
|
|
|
kfree(dd);
|
|
|
|
return -ENOMEM;
|
|
|
|
}
|
|
|
|
|
|
|
|
for (i = 0; i < DL_HASH_ENTRIES; i++)
|
|
|
|
INIT_LIST_HEAD(&dd->hash[i]);
|
|
|
|
|
|
|
|
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->dispatch = &q->queue_head;
|
|
|
|
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;
|
|
|
|
e->elevator_data = dd;
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
static void deadline_put_request(request_queue_t *q, struct request *rq)
|
|
|
|
{
|
|
|
|
struct deadline_data *dd = q->elevator->elevator_data;
|
|
|
|
struct deadline_rq *drq = RQ_DATA(rq);
|
|
|
|
|
|
|
|
if (drq) {
|
|
|
|
mempool_free(drq, dd->drq_pool);
|
|
|
|
rq->elevator_private = NULL;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
static int
|
|
|
|
deadline_set_request(request_queue_t *q, struct request *rq, int gfp_mask)
|
|
|
|
{
|
|
|
|
struct deadline_data *dd = q->elevator->elevator_data;
|
|
|
|
struct deadline_rq *drq;
|
|
|
|
|
|
|
|
drq = mempool_alloc(dd->drq_pool, gfp_mask);
|
|
|
|
if (drq) {
|
|
|
|
memset(drq, 0, sizeof(*drq));
|
|
|
|
RB_CLEAR(&drq->rb_node);
|
|
|
|
drq->request = rq;
|
|
|
|
|
|
|
|
INIT_LIST_HEAD(&drq->hash);
|
|
|
|
drq->on_hash = 0;
|
|
|
|
|
|
|
|
INIT_LIST_HEAD(&drq->fifo);
|
|
|
|
|
|
|
|
rq->elevator_private = drq;
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
return 1;
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* sysfs parts below
|
|
|
|
*/
|
|
|
|
struct deadline_fs_entry {
|
|
|
|
struct attribute attr;
|
|
|
|
ssize_t (*show)(struct deadline_data *, char *);
|
|
|
|
ssize_t (*store)(struct deadline_data *, const char *, size_t);
|
|
|
|
};
|
|
|
|
|
|
|
|
static ssize_t
|
|
|
|
deadline_var_show(int var, char *page)
|
|
|
|
{
|
|
|
|
return sprintf(page, "%d\n", var);
|
|
|
|
}
|
|
|
|
|
|
|
|
static ssize_t
|
|
|
|
deadline_var_store(int *var, const char *page, size_t count)
|
|
|
|
{
|
|
|
|
char *p = (char *) page;
|
|
|
|
|
|
|
|
*var = simple_strtol(p, &p, 10);
|
|
|
|
return count;
|
|
|
|
}
|
|
|
|
|
|
|
|
#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
|
|
|
|
static ssize_t __FUNC(struct deadline_data *dd, char *page) \
|
|
|
|
{ \
|
|
|
|
int __data = __VAR; \
|
|
|
|
if (__CONV) \
|
|
|
|
__data = jiffies_to_msecs(__data); \
|
|
|
|
return deadline_var_show(__data, (page)); \
|
|
|
|
}
|
|
|
|
SHOW_FUNCTION(deadline_readexpire_show, dd->fifo_expire[READ], 1);
|
|
|
|
SHOW_FUNCTION(deadline_writeexpire_show, dd->fifo_expire[WRITE], 1);
|
|
|
|
SHOW_FUNCTION(deadline_writesstarved_show, dd->writes_starved, 0);
|
|
|
|
SHOW_FUNCTION(deadline_frontmerges_show, dd->front_merges, 0);
|
|
|
|
SHOW_FUNCTION(deadline_fifobatch_show, dd->fifo_batch, 0);
|
|
|
|
#undef SHOW_FUNCTION
|
|
|
|
|
|
|
|
#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
|
|
|
|
static ssize_t __FUNC(struct deadline_data *dd, const char *page, size_t count) \
|
|
|
|
{ \
|
|
|
|
int __data; \
|
|
|
|
int ret = deadline_var_store(&__data, (page), count); \
|
|
|
|
if (__data < (MIN)) \
|
|
|
|
__data = (MIN); \
|
|
|
|
else if (__data > (MAX)) \
|
|
|
|
__data = (MAX); \
|
|
|
|
if (__CONV) \
|
|
|
|
*(__PTR) = msecs_to_jiffies(__data); \
|
|
|
|
else \
|
|
|
|
*(__PTR) = __data; \
|
|
|
|
return ret; \
|
|
|
|
}
|
|
|
|
STORE_FUNCTION(deadline_readexpire_store, &dd->fifo_expire[READ], 0, INT_MAX, 1);
|
|
|
|
STORE_FUNCTION(deadline_writeexpire_store, &dd->fifo_expire[WRITE], 0, INT_MAX, 1);
|
|
|
|
STORE_FUNCTION(deadline_writesstarved_store, &dd->writes_starved, INT_MIN, INT_MAX, 0);
|
|
|
|
STORE_FUNCTION(deadline_frontmerges_store, &dd->front_merges, 0, 1, 0);
|
|
|
|
STORE_FUNCTION(deadline_fifobatch_store, &dd->fifo_batch, 0, INT_MAX, 0);
|
|
|
|
#undef STORE_FUNCTION
|
|
|
|
|
|
|
|
static struct deadline_fs_entry deadline_readexpire_entry = {
|
|
|
|
.attr = {.name = "read_expire", .mode = S_IRUGO | S_IWUSR },
|
|
|
|
.show = deadline_readexpire_show,
|
|
|
|
.store = deadline_readexpire_store,
|
|
|
|
};
|
|
|
|
static struct deadline_fs_entry deadline_writeexpire_entry = {
|
|
|
|
.attr = {.name = "write_expire", .mode = S_IRUGO | S_IWUSR },
|
|
|
|
.show = deadline_writeexpire_show,
|
|
|
|
.store = deadline_writeexpire_store,
|
|
|
|
};
|
|
|
|
static struct deadline_fs_entry deadline_writesstarved_entry = {
|
|
|
|
.attr = {.name = "writes_starved", .mode = S_IRUGO | S_IWUSR },
|
|
|
|
.show = deadline_writesstarved_show,
|
|
|
|
.store = deadline_writesstarved_store,
|
|
|
|
};
|
|
|
|
static struct deadline_fs_entry deadline_frontmerges_entry = {
|
|
|
|
.attr = {.name = "front_merges", .mode = S_IRUGO | S_IWUSR },
|
|
|
|
.show = deadline_frontmerges_show,
|
|
|
|
.store = deadline_frontmerges_store,
|
|
|
|
};
|
|
|
|
static struct deadline_fs_entry deadline_fifobatch_entry = {
|
|
|
|
.attr = {.name = "fifo_batch", .mode = S_IRUGO | S_IWUSR },
|
|
|
|
.show = deadline_fifobatch_show,
|
|
|
|
.store = deadline_fifobatch_store,
|
|
|
|
};
|
|
|
|
|
|
|
|
static struct attribute *default_attrs[] = {
|
|
|
|
&deadline_readexpire_entry.attr,
|
|
|
|
&deadline_writeexpire_entry.attr,
|
|
|
|
&deadline_writesstarved_entry.attr,
|
|
|
|
&deadline_frontmerges_entry.attr,
|
|
|
|
&deadline_fifobatch_entry.attr,
|
|
|
|
NULL,
|
|
|
|
};
|
|
|
|
|
|
|
|
#define to_deadline(atr) container_of((atr), struct deadline_fs_entry, attr)
|
|
|
|
|
|
|
|
static ssize_t
|
|
|
|
deadline_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
|
|
|
|
{
|
|
|
|
elevator_t *e = container_of(kobj, elevator_t, kobj);
|
|
|
|
struct deadline_fs_entry *entry = to_deadline(attr);
|
|
|
|
|
|
|
|
if (!entry->show)
|
2005-04-29 14:26:06 +08:00
|
|
|
return -EIO;
|
2005-04-17 06:20:36 +08:00
|
|
|
|
|
|
|
return entry->show(e->elevator_data, page);
|
|
|
|
}
|
|
|
|
|
|
|
|
static ssize_t
|
|
|
|
deadline_attr_store(struct kobject *kobj, struct attribute *attr,
|
|
|
|
const char *page, size_t length)
|
|
|
|
{
|
|
|
|
elevator_t *e = container_of(kobj, elevator_t, kobj);
|
|
|
|
struct deadline_fs_entry *entry = to_deadline(attr);
|
|
|
|
|
|
|
|
if (!entry->store)
|
2005-04-29 14:26:06 +08:00
|
|
|
return -EIO;
|
2005-04-17 06:20:36 +08:00
|
|
|
|
|
|
|
return entry->store(e->elevator_data, page, length);
|
|
|
|
}
|
|
|
|
|
|
|
|
static struct sysfs_ops deadline_sysfs_ops = {
|
|
|
|
.show = deadline_attr_show,
|
|
|
|
.store = deadline_attr_store,
|
|
|
|
};
|
|
|
|
|
|
|
|
static struct kobj_type deadline_ktype = {
|
|
|
|
.sysfs_ops = &deadline_sysfs_ops,
|
|
|
|
.default_attrs = default_attrs,
|
|
|
|
};
|
|
|
|
|
|
|
|
static struct elevator_type iosched_deadline = {
|
|
|
|
.ops = {
|
|
|
|
.elevator_merge_fn = deadline_merge,
|
|
|
|
.elevator_merged_fn = deadline_merged_request,
|
|
|
|
.elevator_merge_req_fn = deadline_merged_requests,
|
|
|
|
.elevator_next_req_fn = deadline_next_request,
|
|
|
|
.elevator_add_req_fn = deadline_insert_request,
|
|
|
|
.elevator_remove_req_fn = deadline_remove_request,
|
|
|
|
.elevator_queue_empty_fn = deadline_queue_empty,
|
|
|
|
.elevator_former_req_fn = deadline_former_request,
|
|
|
|
.elevator_latter_req_fn = deadline_latter_request,
|
|
|
|
.elevator_set_req_fn = deadline_set_request,
|
|
|
|
.elevator_put_req_fn = deadline_put_request,
|
|
|
|
.elevator_init_fn = deadline_init_queue,
|
|
|
|
.elevator_exit_fn = deadline_exit_queue,
|
|
|
|
},
|
|
|
|
|
|
|
|
.elevator_ktype = &deadline_ktype,
|
|
|
|
.elevator_name = "deadline",
|
|
|
|
.elevator_owner = THIS_MODULE,
|
|
|
|
};
|
|
|
|
|
|
|
|
static int __init deadline_init(void)
|
|
|
|
{
|
|
|
|
int ret;
|
|
|
|
|
|
|
|
drq_pool = kmem_cache_create("deadline_drq", sizeof(struct deadline_rq),
|
|
|
|
0, 0, NULL, NULL);
|
|
|
|
|
|
|
|
if (!drq_pool)
|
|
|
|
return -ENOMEM;
|
|
|
|
|
|
|
|
ret = elv_register(&iosched_deadline);
|
|
|
|
if (ret)
|
|
|
|
kmem_cache_destroy(drq_pool);
|
|
|
|
|
|
|
|
return ret;
|
|
|
|
}
|
|
|
|
|
|
|
|
static void __exit deadline_exit(void)
|
|
|
|
{
|
|
|
|
kmem_cache_destroy(drq_pool);
|
|
|
|
elv_unregister(&iosched_deadline);
|
|
|
|
}
|
|
|
|
|
|
|
|
module_init(deadline_init);
|
|
|
|
module_exit(deadline_exit);
|
|
|
|
|
|
|
|
MODULE_AUTHOR("Jens Axboe");
|
|
|
|
MODULE_LICENSE("GPL");
|
|
|
|
MODULE_DESCRIPTION("deadline IO scheduler");
|