[PATCH] 2.6.0-test4 CFQ io scheduler

Jens Axboe
2003-08-29T08:16:56Z

On Fri, Aug 29 2003, Jens Axboe wrote:
> On Thu, Aug 28 2003, Felipe Alfaro Solana wrote:
> > On Thu, 2003-08-28 at 21:47, Jens Axboe wrote:
> >
> > > It shouldn't be too hard to adapt the latest version from before -mm
> > > dropped it and adapting to the current kernels. If you want to give that
> > > a go, I'd be happy to help you out.
> >
> > Why don't you post a patch against 2.6.0-test4 or 2.6.0-test4-mm1 on
> > LKML? I would like to start using CFQ again :-)
>
> Heh, did you not read the email? :)
>
> I'll see if I get squeeze it in today, stay tuned.

Alright, here's a version for 2.6.0-test4. It builds, it survived a 128
client dbench on SMP. And that's all the testing I did, so be careful.

You need to boot with elevator=cfq to activate it.

# This is a BitKeeper generated patch for the following project:
# Project Name: Linux kernel tree
# This patch format is intended for GNU patch command version 2.5 or higher.
# This patch includes the following deltas:
# ChangeSet 1.1291 -> 1.1292
# include/linux/elevator.h 1.27 -> 1.28
# drivers/block/Kconfig.iosched 1.2 -> 1.3
# drivers/block/ll_rw_blk.c 1.206 -> 1.207
# drivers/block/Makefile 1.21 -> 1.22
#
# The following is the BitKeeper ChangeSet Log
# --------------------------------------------
# 03/08/29 axboe@smithers.home.kernel.dk 1.1292
# CFQ I/O scheduler
# --------------------------------------------
#
diff -Nru a/drivers/block/Kconfig.iosched b/drivers/block/Kconfig.iosched
--- a/drivers/block/Kconfig.iosched Fri Aug 29 10:14:28 2003
+++ b/drivers/block/Kconfig.iosched Fri Aug 29 10:14:28 2003
@@ -27,3 +27,10 @@
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
+ bool "CFQ I/O scheduler" if EMBEDDED
+ default y
+ ---help---
+ The CFQ I/O scheduler tries to distribute bandwidth equally
+ among all processes in the system. It should provide a fair
+ working environment, suitable for desktop systems.
diff -Nru a/drivers/block/Makefile b/drivers/block/Makefile
--- a/drivers/block/Makefile Fri Aug 29 10:14:28 2003
+++ b/drivers/block/Makefile Fri Aug 29 10:14:28 2003
@@ -18,6 +18,7 @@
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-$(CONFIG_MAC_FLOPPY) += swim3.o
obj-$(CONFIG_BLK_DEV_FD) += floppy.o
obj-$(CONFIG_BLK_DEV_FD98) += floppy98.o
diff -Nru a/drivers/block/ll_rw_blk.c b/drivers/block/ll_rw_blk.c
--- a/drivers/block/ll_rw_blk.c Fri Aug 29 10:14:28 2003
+++ b/drivers/block/ll_rw_blk.c Fri Aug 29 10:14:28 2003
@@ -1231,6 +1231,8 @@
&iosched_as;
#elif defined(CONFIG_IOSCHED_DEADLINE)
&iosched_deadline;
+#elif defined(CONFIG_IOSCHED_CFQ)
+ &iosched_cfq;
#elif defined(CONFIG_IOSCHED_NOOP)
&elevator_noop;
#else
@@ -1248,6 +1250,10 @@
#ifdef CONFIG_IOSCHED_AS
if (!strcmp(str, "as"))
chosen_elevator = &iosched_as;
+#endif
+#ifdef CONFIG_IOSCHED_CFQ
+ if (!strcmp(str, "cfq"))
+ chosen_elevator = &iosched_cfq;
#endif
#ifdef CONFIG_IOSCHED_NOOP
if (!strcmp(str, "noop"))
diff -Nru a/include/linux/elevator.h b/include/linux/elevator.h
--- a/include/linux/elevator.h Fri Aug 29 10:14:28 2003
+++ b/include/linux/elevator.h Fri Aug 29 10:14:28 2003
@@ -98,6 +98,11 @@
*/
extern elevator_t iosched_as;

+/*
+ * completely fair queueing I/O scheduler
+ */
+extern elevator_t iosched_cfq;
+
extern int elevator_init(request_queue_t *, elevator_t *);
extern void elevator_exit(request_queue_t *);
extern inline int elv_rq_merge_ok(struct request *, struct bio *);
diff -Nru a/drivers/block/cfq-iosched.c b/drivers/block/cfq-iosched.c
--- /dev/null Wed Dec 31 16:00:00 1969
+++ b/drivers/block/cfq-iosched.c Fri Aug 29 10:14:15 2003
@@ -0,0 +1,690 @@
+/*
+ * linux/drivers/block/cfq-iosched.c
+ *
+ * CFQ, or complete fairness queueing, disk scheduler.
+ *
+ * Based on ideas from a previously unfinished io
+ * scheduler (round robin per-process disk scheduling) and Andrea Arcangeli.
+ *
+ * Copyright (C) 2003 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>
+#include <linux/mempool.h>
+
+/*
+ * tunables
+ */
+static int cfq_quantum = 4;
+static int cfq_queued = 8;
+
+#define CFQ_QHASH_SHIFT 6
+#define CFQ_QHASH_ENTRIES (1 << CFQ_QHASH_SHIFT)
+#define list_entry_qhash(entry) list_entry((entry), struct cfq_queue, cfq_hash)
+
+#define CFQ_MHASH_SHIFT 8
+#define CFQ_MHASH_BLOCK(sec) ((sec) >> 3)
+#define CFQ_MHASH_ENTRIES (1 << CFQ_MHASH_SHIFT)
+#define CFQ_MHASH_FN(sec) (hash_long(CFQ_MHASH_BLOCK((sec)),CFQ_MHASH_SHIFT))
+#define ON_MHASH(crq) !list_empty(&(crq)->hash)
+#define rq_hash_key(rq) ((rq)->sector + (rq)->nr_sectors)
+#define list_entry_hash(ptr) list_entry((ptr), struct cfq_rq, hash)
+
+#define list_entry_cfqq(ptr) list_entry((ptr), struct cfq_queue, cfq_list)
+
+#define RQ_DATA(rq) ((struct cfq_rq *) (rq)->elevator_private)
+
+static kmem_cache_t *crq_pool;
+static kmem_cache_t *cfq_pool;
+static mempool_t *cfq_mpool;
+
+struct cfq_queue {
+ struct list_head cfq_hash;
+ struct list_head cfq_list;
+ struct rb_root sort_list;
+ int pid;
+ int queued[2];
+#if 0
+ /*
+ * with a simple addition like this, we can do io priorities. almost.
+ * does need a split request free list, too.
+ */
+ int io_prio
+#endif
+};
+
+struct cfq_data {
+ struct list_head rr_list;
+ struct list_head *dispatch;
+ struct list_head *cfq_hash;
+
+ struct list_head *crq_hash;
+
+ int busy_queues;
+
+ mempool_t *crq_pool;
+};
+
+struct cfq_rq {
+ struct rb_node rb_node;
+ sector_t rb_key;
+
+ struct request *request;
+
+ struct cfq_queue *cfq_queue;
+
+ struct list_head hash;
+};
+
+static void cfq_put_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq);
+static struct cfq_queue *cfq_find_cfq_hash(struct cfq_data *cfqd, int pid);
+static void cfq_dispatch_sort(struct list_head *head, struct cfq_rq *crq);
+
+/*
+ * lots of deadline iosched dupes, can be abstracted later...
+ */
+static inline void __cfq_del_crq_hash(struct cfq_rq *crq)
+{
+ list_del_init(&crq->hash);
+}
+
+static inline void cfq_del_crq_hash(struct cfq_rq *crq)
+{
+ if (ON_MHASH(crq))
+ __cfq_del_crq_hash(crq);
+}
+
+static void cfq_remove_merge_hints(request_queue_t *q, struct cfq_rq *crq)
+{
+ cfq_del_crq_hash(crq);
+
+ if (q->last_merge == &crq->request->queuelist)
+ q->last_merge = NULL;
+}
+
+static inline void cfq_add_crq_hash(struct cfq_data *cfqd, struct cfq_rq *crq)
+{
+ struct request *rq = crq->request;
+
+ BUG_ON(ON_MHASH(crq));
+
+ list_add(&crq->hash, &cfqd->crq_hash[CFQ_MHASH_FN(rq_hash_key(rq))]);
+}
+
+static struct request *cfq_find_rq_hash(struct cfq_data *cfqd, sector_t offset)
+{
+ struct list_head *hash_list = &cfqd->crq_hash[CFQ_MHASH_FN(offset)];
+ struct list_head *entry, *next = hash_list->next;
+
+ while ((entry = next) != hash_list) {
+ struct cfq_rq *crq = list_entry_hash(entry);
+ struct request *__rq = crq->request;
+
+ next = entry->next;
+
+ BUG_ON(!ON_MHASH(crq));
+
+ if (!rq_mergeable(__rq)) {
+ __cfq_del_crq_hash(crq);
+ continue;
+ }
+
+ if (rq_hash_key(__rq) == offset)
+ return __rq;
+ }
+
+ return NULL;
+}
+
+/*
+ * rb tree support functions
+ */
+#define RB_EMPTY(root) ((root)->rb_node == NULL)
+#define RB_CLEAR(root) ((root)->rb_node = NULL)
+#define ON_RB(crq) ((crq)->cfq_queue != NULL)
+#define rb_entry_crq(node) rb_entry((node), struct cfq_rq, rb_node)
+#define rq_rb_key(rq) (rq)->sector
+
+static inline void cfq_del_crq_rb(struct cfq_queue *cfqq, struct cfq_rq *crq)
+{
+ if (ON_RB(crq)) {
+ cfqq->queued[rq_data_dir(crq->request)]--;
+ rb_erase(&crq->rb_node, &cfqq->sort_list);
+ crq->cfq_queue = NULL;
+ }
+}
+
+static struct cfq_rq *
+__cfq_add_crq_rb(struct cfq_queue *cfqq, struct cfq_rq *crq)
+{
+ struct rb_node **p = &cfqq->sort_list.rb_node;
+ struct rb_node *parent = NULL;
+ struct cfq_rq *__crq;
+
+ while (*p) {
+ parent = *p;
+ __crq = rb_entry_crq(parent);
+
+ if (crq->rb_key < __crq->rb_key)
+ p = &(*p)->rb_left;
+ else if (crq->rb_key > __crq->rb_key)
+ p = &(*p)->rb_right;
+ else
+ return __crq;
+ }
+
+ rb_link_node(&crq->rb_node, parent, p);
+ return 0;
+}
+
+static void
+cfq_add_crq_rb(struct cfq_data *cfqd, struct cfq_queue *cfqq,struct cfq_rq *crq)
+{
+ struct request *rq = crq->request;
+ struct cfq_rq *__alias;
+
+ crq->rb_key = rq_rb_key(rq);
+
+retry:
+ __alias = __cfq_add_crq_rb(cfqq, crq);
+ if (!__alias) {
+ rb_insert_color(&crq->rb_node, &cfqq->sort_list);
+ crq->cfq_queue = cfqq;
+ cfqq->queued[rq_data_dir(rq)]++;
+ return;
+ }
+
+ cfq_del_crq_rb(cfqq, __alias);
+ cfq_dispatch_sort(cfqd->dispatch, __alias);
+ goto retry;
+}
+
+static struct request *
+cfq_find_rq_rb(struct cfq_data *cfqd, sector_t sector)
+{
+ struct cfq_queue *cfqq = cfq_find_cfq_hash(cfqd, current->pid);
+ struct rb_node *n;
+
+ if (!cfqq)
+ goto out;
+
+ n = cfqq->sort_list.rb_node;
+ while (n) {
+ struct cfq_rq *crq = rb_entry_crq(n);
+
+ if (sector < crq->rb_key)
+ n = n->rb_left;
+ else if (sector > crq->rb_key)
+ n = n->rb_right;
+ else
+ return crq->request;
+ }
+
+out:
+ return NULL;
+}
+
+static void cfq_remove_request(request_queue_t *q, struct request *rq)
+{
+ struct cfq_data *cfqd = q->elevator.elevator_data;
+ struct cfq_rq *crq = RQ_DATA(rq);
+
+ if (crq) {
+ struct cfq_queue *cfqq = crq->cfq_queue;
+
+ cfq_remove_merge_hints(q, crq);
+ list_del_init(&rq->queuelist);
+
+ if (cfqq) {
+ cfq_del_crq_rb(cfqq, crq);
+
+ if (RB_EMPTY(&cfqq->sort_list))
+ cfq_put_queue(cfqd, cfqq);
+ }
+ }
+}
+
+static int
+cfq_merge(request_queue_t *q, struct list_head **insert, struct bio *bio)
+{
+ struct cfq_data *cfqd = q->elevator.elevator_data;
+ struct request *__rq;
+ int ret;
+
+ ret = elv_try_last_merge(q, bio);
+ if (ret != ELEVATOR_NO_MERGE) {
+ __rq = list_entry_rq(q->last_merge);
+ goto out_insert;
+ }
+
+ __rq = cfq_find_rq_hash(cfqd, 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;
+ }
+ }
+
+ __rq = cfq_find_rq_rb(cfqd, bio->bi_sector + bio_sectors(bio));
+ if (__rq) {
+ if (elv_rq_merge_ok(__rq, bio)) {
+ ret = ELEVATOR_FRONT_MERGE;
+ goto out;
+ }
+ }
+
+ return ELEVATOR_NO_MERGE;
+out:
+ q->last_merge = &__rq->queuelist;
+out_insert:
+ *insert = &__rq->queuelist;
+ return ret;
+}
+
+static void cfq_merged_request(request_queue_t *q, struct request *req)
+{
+ struct cfq_data *cfqd = q->elevator.elevator_data;
+ struct cfq_rq *crq = RQ_DATA(req);
+
+ cfq_del_crq_hash(crq);
+ cfq_add_crq_hash(cfqd, crq);
+
+ if (ON_RB(crq) && rq_rb_key(req) != crq->rb_key) {
+ struct cfq_queue *cfqq = crq->cfq_queue;
+
+ cfq_del_crq_rb(cfqq, crq);
+ cfq_add_crq_rb(cfqd, cfqq, crq);
+ }
+
+ q->last_merge = &req->queuelist;
+}
+
+static void
+cfq_merged_requests(request_queue_t *q, struct request *req,
+ struct request *next)
+{
+ cfq_merged_request(q, req);
+ cfq_remove_request(q, next);
+}
+
+static void cfq_dispatch_sort(struct list_head *head, struct cfq_rq *crq)
+{
+ struct list_head *entry = head;
+ struct request *__rq;
+
+ if (!list_empty(head)) {
+ __rq = list_entry_rq(head->next);
+
+ if (crq->request->sector < __rq->sector) {
+ entry = head->prev;
+ goto link;
+ }
+ }
+
+ while ((entry = entry->prev) != head) {
+ __rq = list_entry_rq(entry);
+
+ if (crq->request->sector <= __rq->sector)
+ break;
+ }
+
+link:
+ list_add_tail(&crq->request->queuelist, entry);
+}
+
+static inline void
+__cfq_dispatch_requests(struct cfq_data *cfqd, struct cfq_queue *cfqq)
+{
+ struct cfq_rq *crq;
+
+ crq = rb_entry_crq(rb_first(&cfqq->sort_list));
+
+ cfq_del_crq_rb(cfqq, crq);
+ cfq_dispatch_sort(cfqd->dispatch, crq);
+}
+
+static int cfq_dispatch_requests(struct cfq_data *cfqd)
+{
+ struct cfq_queue *cfqq;
+ struct list_head *entry, *tmp;
+ int ret, queued, good_queues;
+
+ if (list_empty(&cfqd->rr_list))
+ return 0;
+
+ queued = ret = 0;
+restart:
+ good_queues = 0;
+ list_for_each_safe(entry, tmp, &cfqd->rr_list) {
+ cfqq = list_entry_cfqq(cfqd->rr_list.next);
+
+ BUG_ON(RB_EMPTY(&cfqq->sort_list));
+
+ __cfq_dispatch_requests(cfqd, cfqq);
+
+ if (RB_EMPTY(&cfqq->sort_list))
+ cfq_put_queue(cfqd, cfqq);
+ else
+ good_queues++;
+
+ queued++;
+ ret = 1;
+ }
+
+ if ((queued < cfq_quantum) && good_queues)
+ goto restart;
+
+ return ret;
+}
+
+static struct request *cfq_next_request(request_queue_t *q)
+{
+ struct cfq_data *cfqd = q->elevator.elevator_data;
+ struct request *rq;
+
+ if (!list_empty(cfqd->dispatch)) {
+ struct cfq_rq *crq;
+dispatch:
+ rq = list_entry_rq(cfqd->dispatch->next);
+
+ if (q->last_merge == &rq->queuelist)
+ q->last_merge = NULL;
+
+ crq = RQ_DATA(rq);
+ if (crq)
+ cfq_del_crq_hash(crq);
+
+ return rq;
+ }
+
+ if (cfq_dispatch_requests(cfqd))
+ goto dispatch;
+
+ return NULL;
+}
+
+static inline struct cfq_queue *
+__cfq_find_cfq_hash(struct cfq_data *cfqd, int pid, const int hashval)
+{
+ struct list_head *hash_list = &cfqd->cfq_hash[hashval];
+ struct list_head *entry;
+
+ list_for_each(entry, hash_list) {
+ struct cfq_queue *__cfqq = list_entry_qhash(entry);
+
+ if (__cfqq->pid == pid)
+ return __cfqq;
+ }
+
+ return NULL;
+}
+
+static struct cfq_queue *cfq_find_cfq_hash(struct cfq_data *cfqd, int pid)
+{
+ const int hashval = hash_long(current->pid, CFQ_QHASH_SHIFT);
+
+ return __cfq_find_cfq_hash(cfqd, pid, hashval);
+}
+
+static void cfq_put_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
+{
+ cfqd->busy_queues--;
+ list_del(&cfqq->cfq_list);
+ list_del(&cfqq->cfq_hash);
+ mempool_free(cfqq, cfq_mpool);
+}
+
+static struct cfq_queue *cfq_get_queue(struct cfq_data *cfqd, int pid)
+{
+ const int hashval = hash_long(current->pid, CFQ_QHASH_SHIFT);
+ struct cfq_queue *cfqq = __cfq_find_cfq_hash(cfqd, pid, hashval);
+
+ if (!cfqq) {
+ cfqq = mempool_alloc(cfq_mpool, GFP_NOIO);
+
+ INIT_LIST_HEAD(&cfqq->cfq_hash);
+ INIT_LIST_HEAD(&cfqq->cfq_list);
+ RB_CLEAR(&cfqq->sort_list);
+
+ cfqq->pid = pid;
+ cfqq->queued[0] = cfqq->queued[1] = 0;
+ list_add(&cfqq->cfq_hash, &cfqd->cfq_hash[hashval]);
+ }
+
+ return cfqq;
+}
+
+static void cfq_enqueue(struct cfq_data *cfqd, struct cfq_rq *crq)
+{
+ struct cfq_queue *cfqq;
+
+ cfqq = cfq_get_queue(cfqd, current->pid);
+
+ cfq_add_crq_rb(cfqd, cfqq, crq);
+
+ if (list_empty(&cfqq->cfq_list)) {
+ list_add(&cfqq->cfq_list, &cfqd->rr_list);
+ cfqd->busy_queues++;
+ }
+}
+
+static void
+cfq_insert_request(request_queue_t *q, struct request *rq,
+ struct list_head *insert_here)
+{
+ struct cfq_data *cfqd = q->elevator.elevator_data;
+ struct cfq_rq *crq = RQ_DATA(rq);
+
+ if (unlikely(!blk_fs_request(rq))) {
+ if (!insert_here)
+ insert_here = cfqd->dispatch->prev;
+
+ list_add(&rq->queuelist, insert_here);
+ return;
+ }
+
+ if (rq_mergeable(rq)) {
+ cfq_add_crq_hash(cfqd, crq);
+
+ if (!q->last_merge)
+ q->last_merge = &rq->queuelist;
+ }
+
+ cfq_enqueue(cfqd, crq);
+}
+
+static int cfq_queue_empty(request_queue_t *q)
+{
+ struct cfq_data *cfqd = q->elevator.elevator_data;
+
+ if (list_empty(cfqd->dispatch) && list_empty(&cfqd->rr_list))
+ return 1;
+
+ return 0;
+}
+
+static struct request *
+cfq_former_request(request_queue_t *q, struct request *rq)
+{
+ struct cfq_rq *crq = RQ_DATA(rq);
+ struct rb_node *rbprev = rb_prev(&crq->rb_node);
+
+ if (rbprev)
+ return rb_entry_crq(rbprev)->request;
+
+ return NULL;
+}
+
+static struct request *
+cfq_latter_request(request_queue_t *q, struct request *rq)
+{
+ struct cfq_rq *crq = RQ_DATA(rq);
+ struct rb_node *rbnext = rb_next(&crq->rb_node);
+
+ if (rbnext)
+ return rb_entry_crq(rbnext)->request;
+
+ return NULL;
+}
+
+static int cfq_may_queue(request_queue_t *q, int rw)
+{
+ struct cfq_data *cfqd = q->elevator.elevator_data;
+ struct cfq_queue *cfqq;
+ int limit, ret = 1;
+
+ if (!cfqd->busy_queues)
+ goto out;
+
+ cfqq = cfq_find_cfq_hash(cfqd, current->pid);
+ if (!cfqq)
+ goto out;
+
+ if (cfqq->queued[rw] < cfq_queued)
+ goto out;
+
+ limit = (q->nr_requests - cfq_queued) / cfqd->busy_queues;
+ if (cfqq->queued[rw] > limit)
+ ret = 0;
+
+out:
+ return ret;
+}
+
+static void cfq_put_request(request_queue_t *q, struct request *rq)
+{
+ struct cfq_data *cfqd = q->elevator.elevator_data;
+ struct cfq_rq *crq = RQ_DATA(rq);
+
+ if (crq) {
+ BUG_ON(q->last_merge == &rq->queuelist);
+ BUG_ON(ON_MHASH(crq));
+
+ mempool_free(crq, cfqd->crq_pool);
+ rq->elevator_private = NULL;
+ }
+}
+
+static int cfq_set_request(request_queue_t *q, struct request *rq, int gfp_mask)
+{
+ struct cfq_data *cfqd = q->elevator.elevator_data;
+ struct cfq_rq *crq = mempool_alloc(cfqd->crq_pool, gfp_mask);
+
+ if (crq) {
+ crq->request = rq;
+ crq->cfq_queue = NULL;
+ INIT_LIST_HEAD(&crq->hash);
+ rq->elevator_private = crq;
+ return 0;
+ }
+
+ return 1;
+}
+
+static void cfq_exit(request_queue_t *q, elevator_t *e)
+{
+ struct cfq_data *cfqd = e->elevator_data;
+
+ e->elevator_data = NULL;
+ mempool_destroy(cfqd->crq_pool);
+ kfree(cfqd->crq_hash);
+ kfree(cfqd->cfq_hash);
+ kfree(cfqd);
+}
+
+static int cfq_init(request_queue_t *q, elevator_t *e)
+{
+ struct cfq_data *cfqd;
+ int i;
+
+ cfqd = kmalloc(sizeof(*cfqd), GFP_KERNEL);
+ if (!cfqd)
+ return -ENOMEM;
+
+ memset(cfqd, 0, sizeof(*cfqd));
+ INIT_LIST_HEAD(&cfqd->rr_list);
+
+ cfqd->crq_hash = kmalloc(sizeof(struct list_head) * CFQ_MHASH_ENTRIES, GFP_KERNEL);
+ if (!cfqd->crq_hash)
+ goto out_crqhash;
+
+ cfqd->cfq_hash = kmalloc(sizeof(struct list_head) * CFQ_QHASH_ENTRIES, GFP_KERNEL);
+ if (!cfqd->cfq_hash)
+ goto out_cfqhash;
+
+ cfqd->crq_pool = mempool_create(BLKDEV_MIN_RQ, mempool_alloc_slab, mempool_free_slab, crq_pool);
+ if (!cfqd->crq_pool)
+ goto out_crqpool;
+
+ for (i = 0; i < CFQ_MHASH_ENTRIES; i++)
+ INIT_LIST_HEAD(&cfqd->crq_hash[i]);
+ for (i = 0; i < CFQ_QHASH_ENTRIES; i++)
+ INIT_LIST_HEAD(&cfqd->cfq_hash[i]);
+
+ cfqd->dispatch = &q->queue_head;
+ e->elevator_data = cfqd;
+ return 0;
+out_crqpool:
+ kfree(cfqd->cfq_hash);
+out_cfqhash:
+ kfree(cfqd->crq_hash);
+out_crqhash:
+ kfree(cfqd);
+ return -ENOMEM;
+}
+
+static int __init cfq_slab_setup(void)
+{
+ crq_pool = kmem_cache_create("crq_pool", sizeof(struct cfq_rq), 0, 0,
+ NULL, NULL);
+
+ if (!crq_pool)
+ panic("cfq_iosched: can't init crq pool\n");
+
+ cfq_pool = kmem_cache_create("cfq_pool", sizeof(struct cfq_queue), 0, 0,
+ NULL, NULL);
+
+ if (!cfq_pool)
+ panic("cfq_iosched: can't init cfq pool\n");
+
+ cfq_mpool = mempool_create(64, mempool_alloc_slab, mempool_free_slab, cfq_pool);
+
+ if (!cfq_mpool)
+ panic("cfq_iosched: can't init cfq mpool\n");
+
+ return 0;
+}
+
+subsys_initcall(cfq_slab_setup);
+
+elevator_t iosched_cfq = {
+ .elevator_name = "cfq",
+ .elevator_merge_fn = cfq_merge,
+ .elevator_merged_fn = cfq_merged_request,
+ .elevator_merge_req_fn = cfq_merged_requests,
+ .elevator_next_req_fn = cfq_next_request,
+ .elevator_add_req_fn = cfq_insert_request,
+ .elevator_remove_req_fn = cfq_remove_request,
+ .elevator_queue_empty_fn = cfq_queue_empty,
+ .elevator_former_req_fn = cfq_former_request,
+ .elevator_latter_req_fn = cfq_latter_request,
+ .elevator_set_req_fn = cfq_set_request,
+ .elevator_put_req_fn = cfq_put_request,
+ .elevator_may_queue_fn = cfq_may_queue,
+ .elevator_init_fn = cfq_init,
+ .elevator_exit_fn = cfq_exit,
+};
+
+EXPORT_SYMBOL(iosched_cfq);

--
Jens Axboe