linux/drivers/block/deadline-iosched.c
Jens Axboe 22e2c507c3 [PATCH] Update cfq io scheduler to time sliced design
This updates the CFQ io scheduler to the new time sliced design (cfq
v3).  It provides full process fairness, while giving excellent
aggregate system throughput even for many competing processes.  It
supports io priorities, either inherited from the cpu nice value or set
directly with the ioprio_get/set syscalls.  The latter closely mimic
set/getpriority.

This import is based on my latest from -mm.

Signed-off-by: Jens Axboe <axboe@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-27 14:33:29 -07:00

970 lines
23 KiB
C

/*
* linux/drivers/block/deadline-iosched.c
*
* Deadline i/o scheduler.
*
* Copyright (C) 2002 Jens Axboe <axboe@suse.de>
*/
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/blkdev.h>
#include <linux/elevator.h>
#include <linux/bio.h>
#include <linux/config.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/compiler.h>
#include <linux/hash.h>
#include <linux/rbtree.h>
/*
* See Documentation/block/deadline-iosched.txt
*/
static int read_expire = HZ / 2; /* max time before a read is submitted. */
static int write_expire = 5 * HZ; /* ditto for writes, these limits are SOFT! */
static int writes_starved = 2; /* max times reads can starve a write */
static 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 list_entry_hash(ptr) list_entry((ptr), struct deadline_rq, hash)
#define ON_HASH(drq) (drq)->on_hash
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 deadline_rq *next_drq[2];
struct list_head *dispatch; /* driver dispatch queue */
struct list_head *hash; /* request hash */
unsigned int batching; /* number of sequential requests made */
sector_t last_sector; /* head position */
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;
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 list_head hash;
char on_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)
/*
* the back merge hash support functions
*/
static inline void __deadline_del_drq_hash(struct deadline_rq *drq)
{
drq->on_hash = 0;
list_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 void
deadline_remove_merge_hints(request_queue_t *q, struct deadline_rq *drq)
{
deadline_del_drq_hash(drq);
if (q->last_merge == drq->request)
q->last_merge = NULL;
}
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));
drq->on_hash = 1;
list_add(&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 list_head *head = &dd->hash[DL_HASH_FN(rq_hash_key(rq))];
if (ON_HASH(drq) && drq->hash.prev != head) {
list_del(&drq->hash);
list_add(&drq->hash, head);
}
}
static struct request *
deadline_find_drq_hash(struct deadline_data *dd, sector_t offset)
{
struct list_head *hash_list = &dd->hash[DL_HASH_FN(offset)];
struct list_head *entry, *next = hash_list->next;
while ((entry = next) != hash_list) {
struct deadline_rq *drq = list_entry_hash(entry);
struct request *__rq = drq->request;
next = entry->next;
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_NONE (2)
#define RB_EMPTY(root) ((root)->rb_node == NULL)
#define ON_RB(node) ((node)->rb_color != RB_NONE)
#define RB_CLEAR(node) ((node)->rb_color = RB_NONE)
#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;
}
static void
deadline_add_drq_rb(struct deadline_data *dd, struct deadline_rq *drq)
{
struct deadline_rq *__alias;
drq->rb_key = rq_rb_key(drq->request);
retry:
__alias = __deadline_add_drq_rb(dd, drq);
if (!__alias) {
rb_insert_color(&drq->rb_node, DRQ_RB_ROOT(dd, drq));
return;
}
deadline_move_request(dd, __alias);
goto retry;
}
static inline void
deadline_del_drq_rb(struct deadline_data *dd, struct deadline_rq *drq)
{
const int data_dir = rq_data_dir(drq->request);
if (dd->next_drq[data_dir] == drq) {
struct rb_node *rbnext = rb_next(&drq->rb_node);
dd->next_drq[data_dir] = NULL;
if (rbnext)
dd->next_drq[data_dir] = rb_entry_drq(rbnext);
}
if (ON_RB(&drq->rb_node)) {
rb_erase(&drq->rb_node, DRQ_RB_ROOT(dd, drq));
RB_CLEAR(&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;
}
return NULL;
}
/*
* 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
*/
static inline 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(drq->request);
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);
if (!q->last_merge)
q->last_merge = rq;
}
}
/*
* remove rq from rbtree, fifo, and hash
*/
static void deadline_remove_request(request_queue_t *q, struct request *rq)
{
struct deadline_rq *drq = RQ_DATA(rq);
if (drq) {
struct deadline_data *dd = q->elevator->elevator_data;
list_del_init(&drq->fifo);
deadline_remove_merge_hints(q, drq);
deadline_del_drq_rb(dd, drq);
}
}
static int
deadline_merge(request_queue_t *q, struct request **req, struct bio *bio)
{
struct deadline_data *dd = q->elevator->elevator_data;
struct request *__rq;
int ret;
/*
* try last_merge to avoid going to hash
*/
ret = elv_try_last_merge(q, bio);
if (ret != ELEVATOR_NO_MERGE) {
__rq = q->last_merge;
goto out_insert;
}
/*
* 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);
__rq = deadline_find_drq_rb(dd, rb_key, bio_data_dir(bio));
if (__rq) {
BUG_ON(rb_key != rq_rb_key(__rq));
if (elv_rq_merge_ok(__rq, bio)) {
ret = ELEVATOR_FRONT_MERGE;
goto out;
}
}
}
return ELEVATOR_NO_MERGE;
out:
q->last_merge = __rq;
out_insert:
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)
{
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_node(sizeof(*dd), GFP_KERNEL, q->node);
if (!dd)
return -ENOMEM;
memset(dd, 0, sizeof(*dd));
dd->hash = kmalloc_node(sizeof(struct list_head)*DL_HASH_ENTRIES,
GFP_KERNEL, q->node);
if (!dd->hash) {
kfree(dd);
return -ENOMEM;
}
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 -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, struct bio *bio,
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)
return -EIO;
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)
return -EIO;
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");