This patch removes the Deadline I/O scheduler. Performance-wise, it
should be superceeded by the Elevator I/O scheduler in the following
patch. I would be very ineterested in hearing about any workloads or
benchmarks where Deadline is a substantial improvement over Elevator,
in throughput, fairness, latency, anything.
Signed-off-by: Nate Diller <[email protected]>
---
Documentation/block/deadline-iosched.txt | 78 ---
block/Kconfig.iosched | 14
block/Makefile | 1
block/deadline-iosched.c | 801 -------------------------------
4 files changed, 894 deletions(-)
---
diff -urpN -X dontdiff linux-2.6.18-rc1-mm2/block/deadline-iosched.c
linux-dput/block/deadline-iosched.c
--- linux-2.6.18-rc1-mm2/block/deadline-iosched.c 2006-07-18
14:52:29.000000000 -0700
+++ linux-dput/block/deadline-iosched.c 1969-12-31 16:00:00.000000000 -0800
@@ -1,801 +0,0 @@
-/*
- * Deadline i/o scheduler.
- *
- * Copyright (C) 2002 Jens Axboe <[email protected]>
- */
-#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/hash.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. */
-
-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
- */
-
- /*
- * 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 hlist_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 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)
-
-/*
- * 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;
-}
-
-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);
- }
-
- 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;
- }
-
- 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 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);
-}
-
-/*
- * 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);
- struct deadline_data *dd = q->elevator->elevator_data;
-
- list_del_init(&drq->fifo);
- deadline_del_drq_rb(dd, drq);
- deadline_del_drq_hash(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;
-
- /*
- * 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:
- 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);
- }
-}
-
-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);
- elv_dispatch_add_tail(q, drq->request);
-}
-
-/*
- * 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(request_queue_t *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 deadline_rq *drq;
- int data_dir;
-
- /*
- * batches are currently reads XOR writes
- */
- if (dd->next_drq[WRITE])
- drq = dd->next_drq[WRITE];
- else
- drq = dd->next_drq[READ];
-
- 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_ROOT(&dd->sort_list[READ]));
-
- if (writes && (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
- */
- 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 int deadline_queue_empty(request_queue_t *q)
-{
- struct deadline_data *dd = q->elevator->elevator_data;
-
- return list_empty(&dd->fifo_list[WRITE])
- && 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
- */
-static void *deadline_init_queue(request_queue_t *q, elevator_t *e)
-{
- 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;
- 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;
- 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
- */
-
-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(elevator_t *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(elevator_t *e, const char *page, size_t count) \
-{ \
- struct deadline_data *dd = e->elevator_data; \
- 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_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, S_IRUGO|S_IWUSR, 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 = {
- .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_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_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)
-{
- 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");
diff -urpN -X dontdiff linux-2.6.18-rc1-mm2/block/Kconfig.iosched
linux-dput/block/Kconfig.iosched
--- linux-2.6.18-rc1-mm2/block/Kconfig.iosched 2006-07-18
14:52:29.000000000 -0700
+++ linux-dput/block/Kconfig.iosched 2006-08-03 14:55:51.000000000 -0700
@@ -20,16 +20,6 @@ config IOSCHED_AS
complex when compared to the deadline I/O scheduler, it can also be
slower in some cases especially some database loads.
-config IOSCHED_DEADLINE
- tristate "Deadline I/O scheduler"
- default y
- ---help---
- The deadline I/O scheduler is simple and compact, and is often as
- good as the anticipatory I/O scheduler, and in some database
- workloads, better. In the case of a single process performing I/O to
- a disk at any one time, its behaviour is almost identical to the
- anticipatory I/O scheduler and so is a good choice.
-
config IOSCHED_CFQ
tristate "CFQ I/O scheduler"
default y
@@ -48,9 +38,6 @@ choice
config DEFAULT_AS
bool "Anticipatory" if IOSCHED_AS=y
- config DEFAULT_DEADLINE
- bool "Deadline" if IOSCHED_DEADLINE=y
-
config DEFAULT_CFQ
bool "CFQ" if IOSCHED_CFQ=y
@@ -62,7 +49,6 @@ endchoice
config DEFAULT_IOSCHED
string
default "anticipatory" if DEFAULT_AS
- default "deadline" if DEFAULT_DEADLINE
default "cfq" if DEFAULT_CFQ
default "noop" if DEFAULT_NOOP
diff -urpN -X dontdiff linux-2.6.18-rc1-mm2/block/Makefile
linux-dput/block/Makefile
--- linux-2.6.18-rc1-mm2/block/Makefile 2006-06-17 18:49:35.000000000 -0700
+++ linux-dput/block/Makefile 2006-08-03 15:09:24.000000000 -0700
@@ -6,7 +6,6 @@ obj-y := elevator.o ll_rw_blk.o ioctl.o
obj-$(CONFIG_IOSCHED_NOOP) += noop-iosched.o
obj-$(CONFIG_IOSCHED_AS) += as-iosched.o
-obj-$(CONFIG_IOSCHED_DEADLINE) += deadline-iosched.o
obj-$(CONFIG_IOSCHED_CFQ) += cfq-iosched.o
obj-$(CONFIG_BLK_DEV_IO_TRACE) += blktrace.o
diff -urpN -X dontdiff
linux-2.6.18-rc1-mm2/Documentation/block/deadline-iosched.txt
linux-dput/Documentation/block/deadline-iosched.txt
--- linux-2.6.18-rc1-mm2/Documentation/block/deadline-iosched.txt 2006-06-17
18:49:35.000000000 -0700
+++ linux-dput/Documentation/block/deadline-iosched.txt 1969-12-31
16:00:00.000000000 -0800
@@ -1,78 +0,0 @@
-Deadline IO scheduler tunables
-==============================
-
-This little file attempts to document how the deadline io scheduler works.
-In particular, it will clarify the meaning of the exposed tunables that may be
-of interest to power users.
-
-Each io queue has a set of io scheduler tunables associated with it. These
-tunables control how the io scheduler works. You can find these entries
-in:
-
-/sys/block/<device>/queue/iosched
-
-assuming that you have sysfs mounted on /sys. If you don't have sysfs mounted,
-you can do so by typing:
-
-# mount none /sys -t sysfs
-
-
-********************************************************************************
-
-
-read_expire (in ms)
------------
-
-The goal of the deadline io scheduler is to attempt to guarentee a start
-service time for a request. As we focus mainly on read latencies, this is
-tunable. When a read request first enters the io scheduler, it is assigned
-a deadline that is the current time + the read_expire value in units of
-miliseconds.
-
-
-write_expire (in ms)
------------
-
-Similar to read_expire mentioned above, but for writes.
-
-
-fifo_batch
-----------
-
-When a read request expires its deadline, we must move some requests from
-the sorted io scheduler list to the block device dispatch queue. fifo_batch
-controls how many requests we move, based on the cost of each request. A
-request is either qualified as a seek or a stream. The io scheduler knows
-the last request that was serviced by the drive (or will be serviced right
-before this one). See seek_cost and stream_unit.
-
-
-write_starved (number of dispatches)
--------------
-
-When we have to move requests from the io scheduler queue to the block
-device dispatch queue, we always give a preference to reads. However, we
-don't want to starve writes indefinitely either. So writes_starved controls
-how many times we give preference to reads over writes. When that has been
-done writes_starved number of times, we dispatch some writes based on the
-same criteria as reads.
-
-
-front_merges (bool)
-------------
-
-Sometimes it happens that a request enters the io scheduler that is contigious
-with a request that is already on the queue. Either it fits in the back of that
-request, or it fits at the front. That is called either a back merge candidate
-or a front merge candidate. Due to the way files are typically laid out,
-back merges are much more common than front merges. For some work loads, you
-may even know that it is a waste of time to spend any time attempting to
-front merge requests. Setting front_merges to 0 disables this functionality.
-Front merges may still occur due to the cached last_merge hint, but since
-that comes at basically 0 cost we leave that on. We simply disable the
-rbtree front sector lookup when the io scheduler merge function is called.
-
-
-Nov 11 2002, Jens Axboe <[email protected]>
-
-
-
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