/*
* Deadline i/o scheduler.
*
- * Copyright (C) 2002 Jens Axboe <axboe@suse.de>
+ * Copyright (C) 2002 Jens Axboe <axboe@kernel.dk>
*/
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/compiler.h>
-#include <linux/hash.h>
#include <linux/rbtree.h>
/*
static const int fifo_batch = 16; /* # of sequential requests treated as one
by the above parameters. For throughput. */
-static const int deadline_hash_shift = 5;
-#define DL_HASH_BLOCK(sec) ((sec) >> 3)
-#define DL_HASH_FN(sec) (hash_long(DL_HASH_BLOCK((sec)), deadline_hash_shift))
-#define DL_HASH_ENTRIES (1 << deadline_hash_shift)
-#define rq_hash_key(rq) ((rq)->sector + (rq)->nr_sectors)
-#define ON_HASH(drq) (!hlist_unhashed(&(drq)->hash))
-
struct deadline_data {
/*
* run time data
/*
* next in sort order. read, write or both are NULL
*/
- struct deadline_rq *next_drq[2];
- struct hlist_head *hash; /* request hash */
+ struct request *next_rq[2];
unsigned int batching; /* number of sequential requests made */
sector_t last_sector; /* head position */
unsigned int starved; /* times reads have starved writes */
int fifo_batch;
int writes_starved;
int front_merges;
-
- mempool_t *drq_pool;
};
-/*
- * pre-request data.
- */
-struct deadline_rq {
- /*
- * rbtree index, key is the starting offset
- */
- struct rb_node rb_node;
- sector_t rb_key;
-
- struct request *request;
-
- /*
- * request hash, key is the ending offset (for back merge lookup)
- */
- struct hlist_node hash;
-
- /*
- * expire fifo
- */
- struct list_head fifo;
- unsigned long expires;
-};
-
-static void deadline_move_request(struct deadline_data *dd, struct deadline_rq *drq);
-
-static kmem_cache_t *drq_pool;
-
-#define RQ_DATA(rq) ((struct deadline_rq *) (rq)->elevator_private)
+static void deadline_move_request(struct deadline_data *, struct request *);
-/*
- * the back merge hash support functions
- */
-static inline void __deadline_del_drq_hash(struct deadline_rq *drq)
-{
- hlist_del_init(&drq->hash);
-}
-
-static inline void deadline_del_drq_hash(struct deadline_rq *drq)
-{
- if (ON_HASH(drq))
- __deadline_del_drq_hash(drq);
-}
-
-static inline void
-deadline_add_drq_hash(struct deadline_data *dd, struct deadline_rq *drq)
-{
- struct request *rq = drq->request;
-
- BUG_ON(ON_HASH(drq));
-
- hlist_add_head(&drq->hash, &dd->hash[DL_HASH_FN(rq_hash_key(rq))]);
-}
-
-/*
- * move hot entry to front of chain
- */
-static inline void
-deadline_hot_drq_hash(struct deadline_data *dd, struct deadline_rq *drq)
-{
- struct request *rq = drq->request;
- struct hlist_head *head = &dd->hash[DL_HASH_FN(rq_hash_key(rq))];
-
- if (ON_HASH(drq) && &drq->hash != head->first) {
- hlist_del(&drq->hash);
- hlist_add_head(&drq->hash, head);
- }
-}
-
-static struct request *
-deadline_find_drq_hash(struct deadline_data *dd, sector_t offset)
-{
- struct hlist_head *hash_list = &dd->hash[DL_HASH_FN(offset)];
- struct hlist_node *entry, *next;
- struct deadline_rq *drq;
-
- hlist_for_each_entry_safe(drq, entry, next, hash_list, hash) {
- struct request *__rq = drq->request;
-
- BUG_ON(!ON_HASH(drq));
-
- if (!rq_mergeable(__rq)) {
- __deadline_del_drq_hash(drq);
- continue;
- }
-
- if (rq_hash_key(__rq) == offset)
- return __rq;
- }
-
- return NULL;
-}
-
-/*
- * rb tree support functions
- */
-#define rb_entry_drq(node) rb_entry((node), struct deadline_rq, rb_node)
-#define DRQ_RB_ROOT(dd, drq) (&(dd)->sort_list[rq_data_dir((drq)->request)])
-#define rq_rb_key(rq) (rq)->sector
-
-static struct deadline_rq *
-__deadline_add_drq_rb(struct deadline_data *dd, struct deadline_rq *drq)
-{
- struct rb_node **p = &DRQ_RB_ROOT(dd, drq)->rb_node;
- struct rb_node *parent = NULL;
- struct deadline_rq *__drq;
-
- while (*p) {
- parent = *p;
- __drq = rb_entry_drq(parent);
-
- if (drq->rb_key < __drq->rb_key)
- p = &(*p)->rb_left;
- else if (drq->rb_key > __drq->rb_key)
- p = &(*p)->rb_right;
- else
- return __drq;
- }
-
- rb_link_node(&drq->rb_node, parent, p);
- return NULL;
-}
+#define RQ_RB_ROOT(dd, rq) (&(dd)->sort_list[rq_data_dir((rq))])
static void
-deadline_add_drq_rb(struct deadline_data *dd, struct deadline_rq *drq)
+deadline_add_rq_rb(struct deadline_data *dd, struct request *rq)
{
- struct deadline_rq *__alias;
-
- drq->rb_key = rq_rb_key(drq->request);
+ struct rb_root *root = RQ_RB_ROOT(dd, rq);
+ struct request *__alias;
retry:
- __alias = __deadline_add_drq_rb(dd, drq);
- if (!__alias) {
- rb_insert_color(&drq->rb_node, DRQ_RB_ROOT(dd, drq));
- return;
+ __alias = elv_rb_add(root, rq);
+ if (unlikely(__alias)) {
+ deadline_move_request(dd, __alias);
+ goto retry;
}
-
- deadline_move_request(dd, __alias);
- goto retry;
}
static inline void
-deadline_del_drq_rb(struct deadline_data *dd, struct deadline_rq *drq)
+deadline_del_rq_rb(struct deadline_data *dd, struct request *rq)
{
- const int data_dir = rq_data_dir(drq->request);
+ const int data_dir = rq_data_dir(rq);
- if (dd->next_drq[data_dir] == drq) {
- struct rb_node *rbnext = rb_next(&drq->rb_node);
+ if (dd->next_rq[data_dir] == rq) {
+ struct rb_node *rbnext = rb_next(&rq->rb_node);
- dd->next_drq[data_dir] = NULL;
+ dd->next_rq[data_dir] = NULL;
if (rbnext)
- dd->next_drq[data_dir] = rb_entry_drq(rbnext);
- }
-
- BUG_ON(!RB_EMPTY_NODE(&drq->rb_node));
- rb_erase(&drq->rb_node, DRQ_RB_ROOT(dd, drq));
- RB_CLEAR_NODE(&drq->rb_node);
-}
-
-static struct request *
-deadline_find_drq_rb(struct deadline_data *dd, sector_t sector, int data_dir)
-{
- struct rb_node *n = dd->sort_list[data_dir].rb_node;
- struct deadline_rq *drq;
-
- while (n) {
- drq = rb_entry_drq(n);
-
- if (sector < drq->rb_key)
- n = n->rb_left;
- else if (sector > drq->rb_key)
- n = n->rb_right;
- else
- return drq->request;
+ dd->next_rq[data_dir] = rb_entry_rq(rbnext);
}
- return NULL;
+ elv_rb_del(RQ_RB_ROOT(dd, rq), rq);
}
/*
- * deadline_find_first_drq finds the first (lowest sector numbered) request
- * for the specified data_dir. Used to sweep back to the start of the disk
- * (1-way elevator) after we process the last (highest sector) request.
- */
-static struct deadline_rq *
-deadline_find_first_drq(struct deadline_data *dd, int data_dir)
-{
- struct rb_node *n = dd->sort_list[data_dir].rb_node;
-
- for (;;) {
- if (n->rb_left == NULL)
- return rb_entry_drq(n);
-
- n = n->rb_left;
- }
-}
-
-/*
- * add drq to rbtree and fifo
+ * 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;
- struct deadline_rq *drq = RQ_DATA(rq);
+ const int data_dir = rq_data_dir(rq);
- const int data_dir = rq_data_dir(drq->request);
+ deadline_add_rq_rb(dd, rq);
- deadline_add_drq_rb(dd, drq);
/*
* set expire time (only used for reads) and add to fifo list
*/
- drq->expires = jiffies + dd->fifo_expire[data_dir];
- list_add_tail(&drq->fifo, &dd->fifo_list[data_dir]);
-
- if (rq_mergeable(rq))
- deadline_add_drq_hash(dd, drq);
+ rq_set_fifo_time(rq, jiffies + dd->fifo_expire[data_dir]);
+ list_add_tail(&rq->queuelist, &dd->fifo_list[data_dir]);
}
/*
- * remove rq from rbtree, fifo, and hash
+ * remove rq from rbtree and fifo.
*/
static void deadline_remove_request(request_queue_t *q, struct request *rq)
{
- struct deadline_rq *drq = RQ_DATA(rq);
struct deadline_data *dd = q->elevator->elevator_data;
- list_del_init(&drq->fifo);
- deadline_del_drq_rb(dd, drq);
- deadline_del_drq_hash(drq);
+ rq_fifo_clear(rq);
+ deadline_del_rq_rb(dd, rq);
}
static int
struct request *__rq;
int ret;
- /*
- * see if the merge hash can satisfy a back merge
- */
- __rq = deadline_find_drq_hash(dd, bio->bi_sector);
- if (__rq) {
- BUG_ON(__rq->sector + __rq->nr_sectors != bio->bi_sector);
-
- if (elv_rq_merge_ok(__rq, bio)) {
- ret = ELEVATOR_BACK_MERGE;
- goto out;
- }
- }
-
/*
* check for front merge
*/
if (dd->front_merges) {
- sector_t rb_key = bio->bi_sector + bio_sectors(bio);
+ sector_t sector = bio->bi_sector + bio_sectors(bio);
- __rq = deadline_find_drq_rb(dd, rb_key, bio_data_dir(bio));
+ __rq = elv_rb_find(&dd->sort_list[bio_data_dir(bio)], sector);
if (__rq) {
- BUG_ON(rb_key != rq_rb_key(__rq));
+ BUG_ON(sector != __rq->sector);
if (elv_rq_merge_ok(__rq, bio)) {
ret = ELEVATOR_FRONT_MERGE;
return ELEVATOR_NO_MERGE;
out:
- if (ret)
- deadline_hot_drq_hash(dd, RQ_DATA(__rq));
*req = __rq;
return ret;
}
-static void deadline_merged_request(request_queue_t *q, struct request *req)
+static void deadline_merged_request(request_queue_t *q, struct request *req,
+ int type)
{
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);
+ if (type == ELEVATOR_FRONT_MERGE) {
+ elv_rb_del(RQ_RB_ROOT(dd, req), req);
+ deadline_add_rq_rb(dd, req);
}
}
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
+ * if next expires before rq, assign its expire time to rq
+ * and move into next position (next will be deleted) in fifo
*/
- 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;
+ if (!list_empty(&req->queuelist) && !list_empty(&next->queuelist)) {
+ if (time_before(rq_fifo_time(next), rq_fifo_time(req))) {
+ list_move(&req->queuelist, &next->queuelist);
+ rq_set_fifo_time(req, rq_fifo_time(next));
}
}
* move request from sort list to dispatch queue.
*/
static inline void
-deadline_move_to_dispatch(struct deadline_data *dd, struct deadline_rq *drq)
+deadline_move_to_dispatch(struct deadline_data *dd, struct request *rq)
{
- request_queue_t *q = drq->request->q;
+ request_queue_t *q = rq->q;
- deadline_remove_request(q, drq->request);
- elv_dispatch_add_tail(q, drq->request);
+ 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 deadline_rq *drq)
+deadline_move_request(struct deadline_data *dd, struct request *rq)
{
- const int data_dir = rq_data_dir(drq->request);
- struct rb_node *rbnext = rb_next(&drq->rb_node);
+ const int data_dir = rq_data_dir(rq);
+ struct rb_node *rbnext = rb_next(&rq->rb_node);
- dd->next_drq[READ] = NULL;
- dd->next_drq[WRITE] = NULL;
+ dd->next_rq[READ] = NULL;
+ dd->next_rq[WRITE] = NULL;
if (rbnext)
- dd->next_drq[data_dir] = rb_entry_drq(rbnext);
+ dd->next_rq[data_dir] = rb_entry_rq(rbnext);
- dd->last_sector = drq->request->sector + drq->request->nr_sectors;
+ dd->last_sector = rq->sector + rq->nr_sectors;
/*
* take it off the sort and fifo list, move
* to dispatch queue
*/
- deadline_move_to_dispatch(dd, drq);
+ deadline_move_to_dispatch(dd, rq);
}
-#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);
+ struct request *rq = rq_entry_fifo(dd->fifo_list[ddir].next);
/*
- * drq is expired!
+ * rq is expired!
*/
- if (time_after(jiffies, drq->expires))
+ if (time_after(jiffies, rq_fifo_time(rq)))
return 1;
return 0;
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 deadline_rq *drq;
+ struct request *rq;
int data_dir;
/*
* batches are currently reads XOR writes
*/
- if (dd->next_drq[WRITE])
- drq = dd->next_drq[WRITE];
+ if (dd->next_rq[WRITE])
+ rq = dd->next_rq[WRITE];
else
- drq = dd->next_drq[READ];
+ rq = dd->next_rq[READ];
- if (drq) {
+ if (rq) {
/* we have a "next request" */
- if (dd->last_sector != drq->request->sector)
+ if (dd->last_sector != rq->sector)
/* end the batch on a non sequential request */
dd->batching += dd->fifo_batch;
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);
+ rq = rq_entry_fifo(dd->fifo_list[data_dir].next);
- } else if (dd->next_drq[data_dir]) {
+ } else if (dd->next_rq[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];
+ rq = dd->next_rq[data_dir];
} else {
+ struct rb_node *node;
/*
* 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);
+ node = rb_first(&dd->sort_list[data_dir]);
+ if (node)
+ rq = rb_entry_rq(node);
}
dispatch_request:
/*
- * drq is the selected appropriate request.
+ * rq is the selected appropriate request.
*/
dd->batching++;
- deadline_move_request(dd, drq);
+ deadline_move_request(dd, rq);
return 1;
}
&& list_empty(&dd->fifo_list[READ]);
}
-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
+ * initialize elevator private data (deadline_data).
*/
-static void *deadline_init_queue(request_queue_t *q, elevator_t *e)
+static void *deadline_init_queue(request_queue_t *q)
{
struct deadline_data *dd;
- int i;
-
- if (!drq_pool)
- return NULL;
dd = kmalloc_node(sizeof(*dd), GFP_KERNEL, q->node);
if (!dd)
return NULL;
memset(dd, 0, sizeof(*dd));
- dd->hash = kmalloc_node(sizeof(struct hlist_head)*DL_HASH_ENTRIES,
- GFP_KERNEL, q->node);
- if (!dd->hash) {
- kfree(dd);
- return NULL;
- }
-
- dd->drq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab,
- mempool_free_slab, drq_pool, q->node);
- if (!dd->drq_pool) {
- kfree(dd->hash);
- kfree(dd);
- return NULL;
- }
-
- for (i = 0; i < DL_HASH_ENTRIES; i++)
- INIT_HLIST_HEAD(&dd->hash[i]);
-
INIT_LIST_HEAD(&dd->fifo_list[READ]);
INIT_LIST_HEAD(&dd->fifo_list[WRITE]);
dd->sort_list[READ] = RB_ROOT;
return dd;
}
-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);
-
- mempool_free(drq, dd->drq_pool);
- rq->elevator_private = NULL;
-}
-
-static int
-deadline_set_request(request_queue_t *q, struct request *rq, struct bio *bio,
- gfp_t 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_NODE(&drq->rb_node);
- drq->request = rq;
-
- INIT_HLIST_NODE(&drq->hash);
-
- INIT_LIST_HEAD(&drq->fifo);
-
- rq->elevator_private = drq;
- return 0;
- }
-
- return 1;
-}
-
/*
* sysfs parts below
*/
.elevator_dispatch_fn = deadline_dispatch_requests,
.elevator_add_req_fn = deadline_add_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_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,
},
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;
+ return elv_register(&iosched_deadline);
}
static void __exit deadline_exit(void)
{
- kmem_cache_destroy(drq_pool);
elv_unregister(&iosched_deadline);
}
git.samba.org / sfrench / cifs-2.6.git / blobdiff