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-rw-r--r--Documentation/block/biodoc.txt113
-rw-r--r--drivers/block/as-iosched.c325
-rw-r--r--drivers/block/cfq-iosched.c364
-rw-r--r--drivers/block/deadline-iosched.c123
-rw-r--r--drivers/block/elevator.c266
-rw-r--r--drivers/block/ll_rw_blk.c23
-rw-r--r--drivers/block/noop-iosched.c48
-rw-r--r--include/linux/blkdev.h26
-rw-r--r--include/linux/elevator.h18
9 files changed, 459 insertions, 847 deletions
diff --git a/Documentation/block/biodoc.txt b/Documentation/block/biodoc.txt
index 6dd274d..2d65c21 100644
--- a/Documentation/block/biodoc.txt
+++ b/Documentation/block/biodoc.txt
@@ -906,9 +906,20 @@ Aside:
4. The I/O scheduler
-I/O schedulers are now per queue. They should be runtime switchable and modular
-but aren't yet. Jens has most bits to do this, but the sysfs implementation is
-missing.
+I/O scheduler, a.k.a. elevator, is implemented in two layers. Generic dispatch
+queue and specific I/O schedulers. Unless stated otherwise, elevator is used
+to refer to both parts and I/O scheduler to specific I/O schedulers.
+
+Block layer implements generic dispatch queue in ll_rw_blk.c and elevator.c.
+The generic dispatch queue is responsible for properly ordering barrier
+requests, requeueing, handling non-fs requests and all other subtleties.
+
+Specific I/O schedulers are responsible for ordering normal filesystem
+requests. They can also choose to delay certain requests to improve
+throughput or whatever purpose. As the plural form indicates, there are
+multiple I/O schedulers. They can be built as modules but at least one should
+be built inside the kernel. Each queue can choose different one and can also
+change to another one dynamically.
A block layer call to the i/o scheduler follows the convention elv_xxx(). This
calls elevator_xxx_fn in the elevator switch (drivers/block/elevator.c). Oh,
@@ -921,44 +932,36 @@ keeping work.
The functions an elevator may implement are: (* are mandatory)
elevator_merge_fn called to query requests for merge with a bio
-elevator_merge_req_fn " " " with another request
+elevator_merge_req_fn called when two requests get merged. the one
+ which gets merged into the other one will be
+ never seen by I/O scheduler again. IOW, after
+ being merged, the request is gone.
elevator_merged_fn called when a request in the scheduler has been
involved in a merge. It is used in the deadline
scheduler for example, to reposition the request
if its sorting order has changed.
-*elevator_next_req_fn returns the next scheduled request, or NULL
- if there are none (or none are ready).
+elevator_dispatch_fn fills the dispatch queue with ready requests.
+ I/O schedulers are free to postpone requests by
+ not filling the dispatch queue unless @force
+ is non-zero. Once dispatched, I/O schedulers
+ are not allowed to manipulate the requests -
+ they belong to generic dispatch queue.
-*elevator_add_req_fn called to add a new request into the scheduler
+elevator_add_req_fn called to add a new request into the scheduler
elevator_queue_empty_fn returns true if the merge queue is empty.
Drivers shouldn't use this, but rather check
if elv_next_request is NULL (without losing the
request if one exists!)
-elevator_remove_req_fn This is called when a driver claims ownership of
- the target request - it now belongs to the
- driver. It must not be modified or merged.
- Drivers must not lose the request! A subsequent
- call of elevator_next_req_fn must return the
- _next_ request.
-
-elevator_requeue_req_fn called to add a request to the scheduler. This
- is used when the request has alrnadebeen
- returned by elv_next_request, but hasn't
- completed. If this is not implemented then
- elevator_add_req_fn is called instead.
-
elevator_former_req_fn
elevator_latter_req_fn These return the request before or after the
one specified in disk sort order. Used by the
block layer to find merge possibilities.
-elevator_completed_req_fn called when a request is completed. This might
- come about due to being merged with another or
- when the device completes the request.
+elevator_completed_req_fn called when a request is completed.
elevator_may_queue_fn returns true if the scheduler wants to allow the
current context to queue a new request even if
@@ -967,13 +970,33 @@ elevator_may_queue_fn returns true if the scheduler wants to allow the
elevator_set_req_fn
elevator_put_req_fn Must be used to allocate and free any elevator
- specific storate for a request.
+ specific storage for a request.
+
+elevator_activate_req_fn Called when device driver first sees a request.
+ I/O schedulers can use this callback to
+ determine when actual execution of a request
+ starts.
+elevator_deactivate_req_fn Called when device driver decides to delay
+ a request by requeueing it.
elevator_init_fn
elevator_exit_fn Allocate and free any elevator specific storage
for a queue.
-4.2 I/O scheduler implementation
+4.2 Request flows seen by I/O schedulers
+All requests seens by I/O schedulers strictly follow one of the following three
+flows.
+
+ set_req_fn ->
+
+ i. add_req_fn -> (merged_fn ->)* -> dispatch_fn -> activate_req_fn ->
+ (deactivate_req_fn -> activate_req_fn ->)* -> completed_req_fn
+ ii. add_req_fn -> (merged_fn ->)* -> merge_req_fn
+ iii. [none]
+
+ -> put_req_fn
+
+4.3 I/O scheduler implementation
The generic i/o scheduler algorithm attempts to sort/merge/batch requests for
optimal disk scan and request servicing performance (based on generic
principles and device capabilities), optimized for:
@@ -993,18 +1016,7 @@ request in sort order to prevent binary tree lookups.
This arrangement is not a generic block layer characteristic however, so
elevators may implement queues as they please.
-ii. Last merge hint
-The last merge hint is part of the generic queue layer. I/O schedulers must do
-some management on it. For the most part, the most important thing is to make
-sure q->last_merge is cleared (set to NULL) when the request on it is no longer
-a candidate for merging (for example if it has been sent to the driver).
-
-The last merge performed is cached as a hint for the subsequent request. If
-sequential data is being submitted, the hint is used to perform merges without
-any scanning. This is not sufficient when there are multiple processes doing
-I/O though, so a "merge hash" is used by some schedulers.
-
-iii. Merge hash
+ii. Merge hash
AS and deadline use a hash table indexed by the last sector of a request. This
enables merging code to quickly look up "back merge" candidates, even when
multiple I/O streams are being performed at once on one disk.
@@ -1013,29 +1025,8 @@ multiple I/O streams are being performed at once on one disk.
are far less common than "back merges" due to the nature of most I/O patterns.
Front merges are handled by the binary trees in AS and deadline schedulers.
-iv. Handling barrier cases
-A request with flags REQ_HARDBARRIER or REQ_SOFTBARRIER must not be ordered
-around. That is, they must be processed after all older requests, and before
-any newer ones. This includes merges!
-
-In AS and deadline schedulers, barriers have the effect of flushing the reorder
-queue. The performance cost of this will vary from nothing to a lot depending
-on i/o patterns and device characteristics. Obviously they won't improve
-performance, so their use should be kept to a minimum.
-
-v. Handling insertion position directives
-A request may be inserted with a position directive. The directives are one of
-ELEVATOR_INSERT_BACK, ELEVATOR_INSERT_FRONT, ELEVATOR_INSERT_SORT.
-
-ELEVATOR_INSERT_SORT is a general directive for non-barrier requests.
-ELEVATOR_INSERT_BACK is used to insert a barrier to the back of the queue.
-ELEVATOR_INSERT_FRONT is used to insert a barrier to the front of the queue, and
-overrides the ordering requested by any previous barriers. In practice this is
-harmless and required, because it is used for SCSI requeueing. This does not
-require flushing the reorder queue, so does not impose a performance penalty.
-
-vi. Plugging the queue to batch requests in anticipation of opportunities for
- merge/sort optimizations
+iii. Plugging the queue to batch requests in anticipation of opportunities for
+ merge/sort optimizations
This is just the same as in 2.4 so far, though per-device unplugging
support is anticipated for 2.5. Also with a priority-based i/o scheduler,
@@ -1069,7 +1060,7 @@ Aside:
blk_kick_queue() to unplug a specific queue (right away ?)
or optionally, all queues, is in the plan.
-4.3 I/O contexts
+4.4 I/O contexts
I/O contexts provide a dynamically allocated per process data area. They may
be used in I/O schedulers, and in the block layer (could be used for IO statis,
priorities for example). See *io_context in drivers/block/ll_rw_blk.c, and
diff --git a/drivers/block/as-iosched.c b/drivers/block/as-iosched.c
index 1f08e14..4081c36 100644
--- a/drivers/block/as-iosched.c
+++ b/drivers/block/as-iosched.c
@@ -98,7 +98,6 @@ struct as_data {
struct as_rq *next_arq[2]; /* next in sort order */
sector_t last_sector[2]; /* last REQ_SYNC & REQ_ASYNC sectors */
- struct list_head *dispatch; /* driver dispatch queue */
struct list_head *hash; /* request hash */
unsigned long exit_prob; /* probability a task will exit while
@@ -239,6 +238,25 @@ static struct io_context *as_get_io_context(void)
return ioc;
}
+static void as_put_io_context(struct as_rq *arq)
+{
+ struct as_io_context *aic;
+
+ if (unlikely(!arq->io_context))
+ return;
+
+ aic = arq->io_context->aic;
+
+ if (arq->is_sync == REQ_SYNC && aic) {
+ spin_lock(&aic->lock);
+ set_bit(AS_TASK_IORUNNING, &aic->state);
+ aic->last_end_request = jiffies;
+ spin_unlock(&aic->lock);
+ }
+
+ put_io_context(arq->io_context);
+}
+
/*
* the back merge hash support functions
*/
@@ -261,14 +279,6 @@ static inline void as_del_arq_hash(struct as_rq *arq)
__as_del_arq_hash(arq);
}
-static void as_remove_merge_hints(request_queue_t *q, struct as_rq *arq)
-{
- as_del_arq_hash(arq);
-
- if (q->last_merge == arq->request)
- q->last_merge = NULL;
-}
-
static void as_add_arq_hash(struct as_data *ad, struct as_rq *arq)
{
struct request *rq = arq->request;
@@ -312,7 +322,7 @@ static struct request *as_find_arq_hash(struct as_data *ad, sector_t offset)
BUG_ON(!arq->on_hash);
if (!rq_mergeable(__rq)) {
- as_remove_merge_hints(ad->q, arq);
+ as_del_arq_hash(arq);
continue;
}
@@ -950,23 +960,12 @@ static void as_completed_request(request_queue_t *q, struct request *rq)
WARN_ON(!list_empty(&rq->queuelist));
- if (arq->state == AS_RQ_PRESCHED) {
- WARN_ON(arq->io_context);
- goto out;
- }
-
- if (arq->state == AS_RQ_MERGED)
- goto out_ioc;
-
if (arq->state != AS_RQ_REMOVED) {
printk("arq->state %d\n", arq->state);
WARN_ON(1);
goto out;
}
- if (!blk_fs_request(rq))
- goto out;
-
if (ad->changed_batch && ad->nr_dispatched == 1) {
kblockd_schedule_work(&ad->antic_work);
ad->changed_batch = 0;
@@ -1001,21 +1000,7 @@ static void as_completed_request(request_queue_t *q, struct request *rq)
}
}
-out_ioc:
- if (!arq->io_context)
- goto out;
-
- if (arq->is_sync == REQ_SYNC) {
- struct as_io_context *aic = arq->io_context->aic;
- if (aic) {
- spin_lock(&aic->lock);
- set_bit(AS_TASK_IORUNNING, &aic->state);
- aic->last_end_request = jiffies;
- spin_unlock(&aic->lock);
- }
- }
-
- put_io_context(arq->io_context);
+ as_put_io_context(arq);
out:
arq->state = AS_RQ_POSTSCHED;
}
@@ -1047,73 +1032,11 @@ static void as_remove_queued_request(request_queue_t *q, struct request *rq)
ad->next_arq[data_dir] = as_find_next_arq(ad, arq);
list_del_init(&arq->fifo);
- as_remove_merge_hints(q, arq);
+ as_del_arq_hash(arq);
as_del_arq_rb(ad, arq);
}
/*
- * as_remove_dispatched_request is called to remove a request which has gone
- * to the dispatch list.
- */
-static void as_remove_dispatched_request(request_queue_t *q, struct request *rq)
-{
- struct as_rq *arq = RQ_DATA(rq);
- struct as_io_context *aic;
-
- if (!arq) {
- WARN_ON(1);
- return;
- }
-
- WARN_ON(arq->state != AS_RQ_DISPATCHED);
- WARN_ON(ON_RB(&arq->rb_node));
- if (arq->io_context && arq->io_context->aic) {
- aic = arq->io_context->aic;
- if (aic) {
- WARN_ON(!atomic_read(&aic->nr_dispatched));
- atomic_dec(&aic->nr_dispatched);
- }
- }
-}
-
-/*
- * as_remove_request is called when a driver has finished with a request.
- * This should be only called for dispatched requests, but for some reason
- * a POWER4 box running hwscan it does not.
- */
-static void as_remove_request(request_queue_t *q, struct request *rq)
-{
- struct as_rq *arq = RQ_DATA(rq);
-
- if (unlikely(arq->state == AS_RQ_NEW))
- goto out;
-
- if (ON_RB(&arq->rb_node)) {
- if (arq->state != AS_RQ_QUEUED) {
- printk("arq->state %d\n", arq->state);
- WARN_ON(1);
- goto out;
- }
- /*
- * We'll lose the aliased request(s) here. I don't think this
- * will ever happen, but if it does, hopefully someone will
- * report it.
- */
- WARN_ON(!list_empty(&rq->queuelist));
- as_remove_queued_request(q, rq);
- } else {
- if (arq->state != AS_RQ_DISPATCHED) {
- printk("arq->state %d\n", arq->state);
- WARN_ON(1);
- goto out;
- }
- as_remove_dispatched_request(q, rq);
- }
-out:
- arq->state = AS_RQ_REMOVED;
-}
-
-/*
* as_fifo_expired returns 0 if there are no expired reads on the fifo,
* 1 otherwise. It is ratelimited so that we only perform the check once per
* `fifo_expire' interval. Otherwise a large number of expired requests
@@ -1165,7 +1088,6 @@ static inline int as_batch_expired(struct as_data *ad)
static void as_move_to_dispatch(struct as_data *ad, struct as_rq *arq)
{
struct request *rq = arq->request;
- struct list_head *insert;
const int data_dir = arq->is_sync;
BUG_ON(!ON_RB(&arq->rb_node));
@@ -1198,13 +1120,13 @@ static void as_move_to_dispatch(struct as_data *ad, struct as_rq *arq)
/*
* take it off the sort and fifo list, add to dispatch queue
*/
- insert = ad->dispatch->prev;
-
while (!list_empty(&rq->queuelist)) {
struct request *__rq = list_entry_rq(rq->queuelist.next);
struct as_rq *__arq = RQ_DATA(__rq);
- list_move_tail(&__rq->queuelist, ad->dispatch);
+ list_del(&__rq->queuelist);
+
+ elv_dispatch_add_tail(ad->q, __rq);
if (__arq->io_context && __arq->io_context->aic)
atomic_inc(&__arq->io_context->aic->nr_dispatched);
@@ -1218,7 +1140,8 @@ static void as_move_to_dispatch(struct as_data *ad, struct as_rq *arq)
as_remove_queued_request(ad->q, rq);
WARN_ON(arq->state != AS_RQ_QUEUED);
- list_add(&rq->queuelist, insert);
+ elv_dispatch_sort(ad->q, rq);
+
arq->state = AS_RQ_DISPATCHED;
if (arq->io_context && arq->io_context->aic)
atomic_inc(&arq->io_context->aic->nr_dispatched);
@@ -1230,12 +1153,42 @@ static void as_move_to_dispatch(struct as_data *ad, struct as_rq *arq)
* read/write expire, batch expire, etc, and moves it to the dispatch
* queue. Returns 1 if a request was found, 0 otherwise.
*/
-static int as_dispatch_request(struct as_data *ad)
+static int as_dispatch_request(request_queue_t *q, int force)
{
+ struct as_data *ad = q->elevator->elevator_data;
struct as_rq *arq;
const int reads = !list_empty(&ad->fifo_list[REQ_SYNC]);
const int writes = !list_empty(&ad->fifo_list[REQ_ASYNC]);
+ if (unlikely(force)) {
+ /*
+ * Forced dispatch, accounting is useless. Reset
+ * accounting states and dump fifo_lists. Note that
+ * batch_data_dir is reset to REQ_SYNC to avoid
+ * screwing write batch accounting as write batch
+ * accounting occurs on W->R transition.
+ */
+ int dispatched = 0;
+
+ ad->batch_data_dir = REQ_SYNC;
+ ad->changed_batch = 0;
+ ad->new_batch = 0;
+
+ while (ad->next_arq[REQ_SYNC]) {
+ as_move_to_dispatch(ad, ad->next_arq[REQ_SYNC]);
+ dispatched++;
+ }
+ ad->last_check_fifo[REQ_SYNC] = jiffies;
+
+ while (ad->next_arq[REQ_ASYNC]) {
+ as_move_to_dispatch(ad, ad->next_arq[REQ_ASYNC]);
+ dispatched++;
+ }
+ ad->last_check_fifo[REQ_ASYNC] = jiffies;
+
+ return dispatched;
+ }
+
/* Signal that the write batch was uncontended, so we can't time it */
if (ad->batch_data_dir == REQ_ASYNC && !reads) {
if (ad->current_write_count == 0 || !writes)
@@ -1359,20 +1312,6 @@ fifo_expired:
return 1;
}
-static struct request *as_next_request(request_queue_t *q)
-{
- struct as_data *ad = q->elevator->elevator_data;
- struct request *rq = NULL;
-
- /*
- * if there are still requests on the dispatch queue, grab the first
- */
- if (!list_empty(ad->dispatch) || as_dispatch_request(ad))
- rq = list_entry_rq(ad->dispatch->next);
-
- return rq;
-}
-
/*
* Add arq to a list behind alias
*/
@@ -1404,17 +1343,25 @@ as_add_aliased_request(struct as_data *ad, struct as_rq *arq, struct as_rq *alia
/*
* Don't want to have to handle merges.
*/
- as_remove_merge_hints(ad->q, arq);
+ as_del_arq_hash(arq);
}
/*
* add arq to rbtree and fifo
*/
-static void as_add_request(struct as_data *ad, struct as_rq *arq)
+static void as_add_request(request_queue_t *q, struct request *rq)
{
+ struct as_data *ad = q->elevator->elevator_data;
+ struct as_rq *arq = RQ_DATA(rq);
struct as_rq *alias;
int data_dir;
+ if (arq->state != AS_RQ_PRESCHED) {
+ printk("arq->state: %d\n", arq->state);
+ WARN_ON(1);
+ }
+ arq->state = AS_RQ_NEW;
+
if (rq_data_dir(arq->request) == READ
|| current->flags&PF_SYNCWRITE)
arq->is_sync = 1;
@@ -1437,12 +1384,8 @@ static void as_add_request(struct as_data *ad, struct as_rq *arq)
arq->expires = jiffies + ad->fifo_expire[data_dir];
list_add_tail(&arq->fifo, &ad->fifo_list[data_dir]);
- if (rq_mergeable(arq->request)) {
+ if (rq_mergeable(arq->request))
as_add_arq_hash(ad, arq);
-
- if (!ad->q->last_merge)
- ad->q->last_merge = arq->request;
- }
as_update_arq(ad, arq); /* keep state machine up to date */
} else {
@@ -1463,96 +1406,24 @@ static void as_add_request(struct as_data *ad, struct as_rq *arq)
arq->state = AS_RQ_QUEUED;
}
-static void as_deactivate_request(request_queue_t *q, struct request *rq)
+static void as_activate_request(request_queue_t *q, struct request *rq)
{
- struct as_data *ad = q->elevator->elevator_data;
struct as_rq *arq = RQ_DATA(rq);
- if (arq) {
- if (arq->state == AS_RQ_REMOVED) {
- arq->state = AS_RQ_DISPATCHED;
- if (arq->io_context && arq->io_context->aic)
- atomic_inc(&arq->io_context->aic->nr_dispatched);
- }
- } else
- WARN_ON(blk_fs_request(rq)
- && (!(rq->flags & (REQ_HARDBARRIER|REQ_SOFTBARRIER))) );
-
- /* Stop anticipating - let this request get through */
- as_antic_stop(ad);
-}
-
-/*
- * requeue the request. The request has not been completed, nor is it a
- * new request, so don't touch accounting.
- */
-static void as_requeue_request(request_queue_t *q, struct request *rq)
-{
- as_deactivate_request(q, rq);
- list_add(&rq->queuelist, &q->queue_head);
-}
-
-/*
- * Account a request that is inserted directly onto the dispatch queue.
- * arq->io_context->aic->nr_dispatched should not need to be incremented
- * because only new requests should come through here: requeues go through
- * our explicit requeue handler.
- */
-static void as_account_queued_request(struct as_data *ad, struct request *rq)
-{
- if (blk_fs_request(rq)) {
- struct as_rq *arq = RQ_DATA(rq);
- arq->state = AS_RQ_DISPATCHED;
- ad->nr_dispatched++;
- }
+ WARN_ON(arq->state != AS_RQ_DISPATCHED);
+ arq->state = AS_RQ_REMOVED;
+ if (arq->io_context && arq->io_context->aic)
+ atomic_dec(&arq->io_context->aic->nr_dispatched);
}
-static void
-as_insert_request(request_queue_t *q, struct request *rq, int where)
+static void as_deactivate_request(request_queue_t *q, struct request *rq)
{
- struct as_data *ad = q->elevator->elevator_data;
struct as_rq *arq = RQ_DATA(rq);
- if (arq) {
- if (arq->state != AS_RQ_PRESCHED) {
- printk("arq->state: %d\n", arq->state);
- WARN_ON(1);
- }
- arq->state = AS_RQ_NEW;
- }
-
- /* barriers must flush the reorder queue */
- if (unlikely(rq->flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER)
- && where == ELEVATOR_INSERT_SORT)) {
- WARN_ON(1);
- where = ELEVATOR_INSERT_BACK;
- }
-
- switch (where) {
- case ELEVATOR_INSERT_BACK:
- while (ad->next_arq[REQ_SYNC])
- as_move_to_dispatch(ad, ad->next_arq[REQ_SYNC]);
-
- while (ad->next_arq[REQ_ASYNC])
- as_move_to_dispatch(ad, ad->next_arq[REQ_ASYNC]);
-
- list_add_tail(&rq->queuelist, ad->dispatch);
- as_account_queued_request(ad, rq);
- as_antic_stop(ad);
- break;
- case ELEVATOR_INSERT_FRONT:
- list_add(&rq->queuelist, ad->dispatch);
- as_account_queued_request(ad, rq);
- as_antic_stop(ad);
- break;
- case ELEVATOR_INSERT_SORT:
- BUG_ON(!blk_fs_request(rq));
- as_add_request(ad, arq);
- break;
- default:
- BUG();
- return;
- }
+ WARN_ON(arq->state != AS_RQ_REMOVED);
+ arq->state = AS_RQ_DISPATCHED;
+ if (arq->io_context && arq->io_context->aic)
+ atomic_inc(&arq->io_context->aic->nr_dispatched);
}
/*
@@ -1565,12 +1436,8 @@ static int as_queue_empty(request_queue_t *q)
{
struct as_data *ad = q->elevator->elevator_data;
- if (!list_empty(&ad->fifo_list[REQ_ASYNC])
- || !list_empty(&ad->fifo_list[REQ_SYNC])
- || !list_empty(ad->dispatch))
- return 0;
-
- return 1;
+ return list_empty(&ad->fifo_list[REQ_ASYNC])
+ && list_empty(&ad->fifo_list[REQ_SYNC]);
}
static struct request *
@@ -1608,15 +1475,6 @@ as_merge(request_queue_t *q, struct request **req, struct bio *bio)
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 = as_find_arq_hash(ad, bio->bi_sector);
@@ -1644,9 +1502,6 @@ as_merge(request_queue_t *q, struct request **req, struct bio *bio)
return ELEVATOR_NO_MERGE;
out:
- if (rq_mergeable(__rq))
- q->last_merge = __rq;
-out_insert:
if (ret) {
if (rq_mergeable(__rq))
as_hot_arq_hash(ad, RQ_DATA(__rq));
@@ -1693,9 +1548,6 @@ static void as_merged_request(request_queue_t *q, struct request *req)
* behind the disk head. We currently don't bother adjusting.
*/
}
-
- if (arq->on_hash)
- q->last_merge = req;
}
static void
@@ -1763,6 +1615,7 @@ as_merged_requests(request_queue_t *q, struct request *req,
* kill knowledge of next, this one is a goner
*/
as_remove_queued_request(q, next);
+ as_put_io_context(anext);
anext->state = AS_RQ_MERGED;
}
@@ -1782,7 +1635,7 @@ static void as_work_handler(void *data)
unsigned long flags;
spin_lock_irqsave(q->queue_lock, flags);
- if (as_next_request(q))
+ if (!as_queue_empty(q))
q->request_fn(q);
spin_unlock_irqrestore(q->queue_lock, flags);
}
@@ -1797,7 +1650,9 @@ static void as_put_request(request_queue_t *q, struct request *rq)
return;
}
- if (arq->state != AS_RQ_POSTSCHED && arq->state != AS_RQ_PRESCHED) {
+ if (unlikely(arq->state != AS_RQ_POSTSCHED &&
+ arq->state != AS_RQ_PRESCHED &&
+ arq->state != AS_RQ_MERGED)) {
printk("arq->state %d\n", arq->state);
WARN_ON(1);
}
@@ -1907,7 +1762,6 @@ static int as_init_queue(request_queue_t *q, elevator_t *e)
INIT_LIST_HEAD(&ad->fifo_list[REQ_ASYNC]);
ad->sort_list[REQ_SYNC] = RB_ROOT;
ad->sort_list[REQ_ASYNC] = RB_ROOT;
- ad->dispatch = &q->queue_head;
ad->fifo_expire[REQ_SYNC] = default_read_expire;
ad->fifo_expire[REQ_ASYNC] = default_write_expire;
ad->antic_expire = default_antic_expire;
@@ -2072,10 +1926,9 @@ static struct elevator_type iosched_as = {
.elevator_merge_fn = as_merge,
.elevator_merged_fn = as_merged_request,
.elevator_merge_req_fn = as_merged_requests,
- .elevator_next_req_fn = as_next_request,
- .elevator_add_req_fn = as_insert_request,
- .elevator_remove_req_fn = as_remove_request,
- .elevator_requeue_req_fn = as_requeue_request,
+ .elevator_dispatch_fn = as_dispatch_request,
+ .elevator_add_req_fn = as_add_request,
+ .elevator_activate_req_fn = as_activate_request,
.elevator_deactivate_req_fn = as_deactivate_request,
.elevator_queue_empty_fn = as_queue_empty,
.elevator_completed_req_fn = as_completed_request,
diff --git a/drivers/block/cfq-iosched.c b/drivers/block/cfq-iosched.c
index d3bfe8c..94690e4 100644
--- a/drivers/block/cfq-iosched.c
+++ b/drivers/block/cfq-iosched.c
@@ -84,7 +84,6 @@ static int cfq_max_depth = 2;
(node)->rb_left = NULL; \
} while (0)
#define RB_CLEAR_ROOT(root) ((root)->rb_node = NULL)
-#define ON_RB(node) ((node)->rb_color != RB_NONE)
#define rb_entry_crq(node) rb_entry((node), struct cfq_rq, rb_node)
#define rq_rb_key(rq) (rq)->sector
@@ -271,10 +270,7 @@ CFQ_CFQQ_FNS(expired);
#undef CFQ_CFQQ_FNS
enum cfq_rq_state_flags {
- CFQ_CRQ_FLAG_in_flight = 0,
- CFQ_CRQ_FLAG_in_driver,
- CFQ_CRQ_FLAG_is_sync,
- CFQ_CRQ_FLAG_requeued,
+ CFQ_CRQ_FLAG_is_sync = 0,
};
#define CFQ_CRQ_FNS(name) \
@@ -291,14 +287,11 @@ static inline int cfq_crq_##name(const struct cfq_rq *crq) \
return (crq->crq_flags & (1 << CFQ_CRQ_FLAG_##name)) != 0; \
}
-CFQ_CRQ_FNS(in_flight);
-CFQ_CRQ_FNS(in_driver);
CFQ_CRQ_FNS(is_sync);
-CFQ_CRQ_FNS(requeued);
#undef CFQ_CRQ_FNS
static struct cfq_queue *cfq_find_cfq_hash(struct cfq_data *, unsigned int, unsigned short);
-static void cfq_dispatch_sort(request_queue_t *, struct cfq_rq *);
+static void cfq_dispatch_insert(request_queue_t *, struct cfq_rq *);
static void cfq_put_cfqd(struct cfq_data *cfqd);
#define process_sync(tsk) ((tsk)->flags & PF_SYNCWRITE)
@@ -311,14 +304,6 @@ static inline void cfq_del_crq_hash(struct cfq_rq *crq)
hlist_del_init(&crq->hash);
}
-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)
- q->last_merge = NULL;
-}
-
static inline void cfq_add_crq_hash(struct cfq_data *cfqd, struct cfq_rq *crq)
{
const int hash_idx = CFQ_MHASH_FN(rq_hash_key(crq->request));
@@ -347,18 +332,13 @@ static struct request *cfq_find_rq_hash(struct cfq_data *cfqd, sector_t offset)
return NULL;
}
-static inline int cfq_pending_requests(struct cfq_data *cfqd)
-{
- return !list_empty(&cfqd->queue->queue_head) || cfqd->busy_queues;
-}
-
/*
* scheduler run of queue, if there are requests pending and no one in the
* driver that will restart queueing
*/
static inline void cfq_schedule_dispatch(struct cfq_data *cfqd)
{
- if (!cfqd->rq_in_driver && cfq_pending_requests(cfqd))
+ if (!cfqd->rq_in_driver && cfqd->busy_queues)
kblockd_schedule_work(&cfqd->unplug_work);
}
@@ -366,7 +346,7 @@ static int cfq_queue_empty(request_queue_t *q)
{
struct cfq_data *cfqd = q->elevator->elevator_data;
- return !cfq_pending_requests(cfqd);
+ return !cfqd->busy_queues;
}
/*
@@ -386,11 +366,6 @@ cfq_choose_req(struct cfq_data *cfqd, struct cfq_rq *crq1, struct cfq_rq *crq2)
if (crq2 == NULL)
return crq1;
- if (cfq_crq_requeued(crq1) && !cfq_crq_requeued(crq2))
- return crq1;
- else if (cfq_crq_requeued(crq2) && !cfq_crq_requeued(crq1))
- return crq2;
-
if (cfq_crq_is_sync(crq1) && !cfq_crq_is_sync(crq2))
return crq1;
else if (cfq_crq_is_sync(crq2) && !cfq_crq_is_sync(crq1))
@@ -461,10 +436,7 @@ cfq_find_next_crq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
struct cfq_rq *crq_next = NULL, *crq_prev = NULL;
struct rb_node *rbnext, *rbprev;
- rbnext = NULL;
- if (ON_RB(&last->rb_node))
- rbnext = rb_next(&last->rb_node);
- if (!rbnext) {
+ if (!(rbnext = rb_next(&last->rb_node))) {
rbnext = rb_first(&cfqq->sort_list);
if (rbnext == &last->rb_node)
rbnext = NULL;
@@ -545,13 +517,13 @@ static void cfq_resort_rr_list(struct cfq_queue *cfqq, int preempted)
* the pending list according to last request service
*/
static inline void
-cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq, int requeue)
+cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
{
BUG_ON(cfq_cfqq_on_rr(cfqq));
cfq_mark_cfqq_on_rr(cfqq);
cfqd->busy_queues++;
- cfq_resort_rr_list(cfqq, requeue);
+ cfq_resort_rr_list(cfqq, 0);
}
static inline void
@@ -571,22 +543,19 @@ cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
static inline void cfq_del_crq_rb(struct cfq_rq *crq)
{
struct cfq_queue *cfqq = crq->cfq_queue;
+ struct cfq_data *cfqd = cfqq->cfqd;
+ const int sync = cfq_crq_is_sync(crq);
- if (ON_RB(&crq->rb_node)) {
- struct cfq_data *cfqd = cfqq->cfqd;
- const int sync = cfq_crq_is_sync(crq);
+ BUG_ON(!cfqq->queued[sync]);
+ cfqq->queued[sync]--;
- BUG_ON(!cfqq->queued[sync]);
- cfqq->queued[sync]--;
+ cfq_update_next_crq(crq);
- cfq_update_next_crq(crq);
+ rb_erase(&crq->rb_node, &cfqq->sort_list);
+ RB_CLEAR_COLOR(&crq->rb_node);
- rb_erase(&crq->rb_node, &cfqq->sort_list);
- RB_CLEAR_COLOR(&crq->rb_node);
-
- if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY(&cfqq->sort_list))
- cfq_del_cfqq_rr(cfqd, cfqq);
- }
+ if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY(&cfqq->sort_list))
+ cfq_del_cfqq_rr(cfqd, cfqq);
}
static struct cfq_rq *
@@ -627,12 +596,12 @@ static void cfq_add_crq_rb(struct cfq_rq *crq)
* if that happens, put the alias on the dispatch list
*/
while ((__alias = __cfq_add_crq_rb(crq)) != NULL)
- cfq_dispatch_sort(cfqd->queue, __alias);
+ cfq_dispatch_insert(cfqd->queue, __alias);
rb_insert_color(&crq->rb_node, &cfqq->sort_list);
if (!cfq_cfqq_on_rr(cfqq))
- cfq_add_cfqq_rr(cfqd, cfqq, cfq_crq_requeued(crq));
+ cfq_add_cfqq_rr(cfqd, cfqq);
/*
* check if this request is a better next-serve candidate
@@ -643,10 +612,8 @@ static void cfq_add_crq_rb(struct cfq_rq *crq)
static inline void
cfq_reposition_crq_rb(struct cfq_queue *cfqq, struct cfq_rq *crq)
{
- if (ON_RB(&crq->rb_node)) {
- rb_erase(&crq->rb_node, &cfqq->sort_list);
- cfqq->queued[cfq_crq_is_sync(crq)]--;
- }
+ rb_erase(&crq->rb_node, &cfqq->sort_list);
+ cfqq->queued[cfq_crq_is_sync(crq)]--;
cfq_add_crq_rb(crq);
}
@@ -676,49 +643,28 @@ out:
return NULL;
}
-static void cfq_deactivate_request(request_queue_t *q, struct request *rq)
+static void cfq_activate_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;
-
- if (cfq_crq_in_driver(crq)) {
- cfq_clear_crq_in_driver(crq);
- WARN_ON(!cfqd->rq_in_driver);
- cfqd->rq_in_driver--;
- }
- if (cfq_crq_in_flight(crq)) {
- const int sync = cfq_crq_is_sync(crq);
- cfq_clear_crq_in_flight(crq);
- WARN_ON(!cfqq->on_dispatch[sync]);
- cfqq->on_dispatch[sync]--;
- }
- cfq_mark_crq_requeued(crq);
- }
+ cfqd->rq_in_driver++;
}
-/*
- * make sure the service time gets corrected on reissue of this request
- */
-static void cfq_requeue_request(request_queue_t *q, struct request *rq)
+static void cfq_deactivate_request(request_queue_t *q, struct request *rq)
{
- cfq_deactivate_request(q, rq);
- list_add(&rq->queuelist, &q->queue_head);
+ struct cfq_data *cfqd = q->elevator->elevator_data;
+
+ WARN_ON(!cfqd->rq_in_driver);
+ cfqd->rq_in_driver--;
}
-static void cfq_remove_request(request_queue_t *q, struct request *rq)
+static void cfq_remove_request(struct request *rq)
{
struct cfq_rq *crq = RQ_DATA(rq);
- if (crq) {
- list_del_init(&rq->queuelist);
- cfq_del_crq_rb(crq);
- cfq_remove_merge_hints(q, crq);
-
- }
+ list_del_init(&rq->queuelist);
+ cfq_del_crq_rb(crq);
+ cfq_del_crq_hash(crq);
}
static int
@@ -728,12 +674,6 @@ cfq_merge(request_queue_t *q, struct request **req, struct bio *bio)
struct request *__rq;
int ret;
- ret = elv_try_last_merge(q, bio);
- if (ret != ELEVATOR_NO_MERGE) {
- __rq = q->last_merge;
- goto out_insert;
- }
-
__rq = cfq_find_rq_hash(cfqd, bio->bi_sector);
if (__rq && elv_rq_merge_ok(__rq, bio)) {
ret = ELEVATOR_BACK_MERGE;
@@ -748,8 +688,6 @@ cfq_merge(request_queue_t *q, struct request **req, struct bio *bio)
return ELEVATOR_NO_MERGE;
out:
- q->last_merge = __rq;
-out_insert:
*req = __rq;
return ret;
}
@@ -762,14 +700,12 @@ static void cfq_merged_request(request_queue_t *q, struct request *req)
cfq_del_crq_hash(crq);
cfq_add_crq_hash(cfqd, crq);
- if (ON_RB(&crq->rb_node) && (rq_rb_key(req) != crq->rb_key)) {
+ if (rq_rb_key(req) != crq->rb_key) {
struct cfq_queue *cfqq = crq->cfq_queue;
cfq_update_next_crq(crq);
cfq_reposition_crq_rb(cfqq, crq);
}
-
- q->last_merge = req;
}
static void
@@ -785,7 +721,7 @@ cfq_merged_requests(request_queue_t *q, struct request *rq,
time_before(next->start_time, rq->start_time))
list_move(&rq->queuelist, &next->queuelist);
- cfq_remove_request(q, next);
+ cfq_remove_request(next);
}
static inline void
@@ -992,53 +928,15 @@ static int cfq_arm_slice_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq)
return 1;
}
-/*
- * we dispatch cfqd->cfq_quantum requests in total from the rr_list queues,
- * this function sector sorts the selected request to minimize seeks. we start
- * at cfqd->last_sector, not 0.
- */
-static void cfq_dispatch_sort(request_queue_t *q, struct cfq_rq *crq)
+static void cfq_dispatch_insert(request_queue_t *q, struct cfq_rq *crq)
{
struct cfq_data *cfqd = q->elevator->elevator_data;
struct cfq_queue *cfqq = crq->cfq_queue;
- struct list_head *head = &q->queue_head, *entry = head;
- struct request *__rq;
- sector_t last;
-
- list_del(&crq->request->queuelist);
-
- last = cfqd->last_sector;
- list_for_each_entry_reverse(__rq, head, queuelist) {
- struct cfq_rq *__crq = RQ_DATA(__rq);
-
- if (blk_barrier_rq(__rq))
- break;
- if (!blk_fs_request(__rq))
- break;
- if (cfq_crq_requeued(__crq))
- break;
-
- if (__rq->sector <= crq->request->sector)
- break;
- if (__rq->sector > last && crq->request->sector < last) {
- last = crq->request->sector + crq->request->nr_sectors;
- break;
- }
- entry = &__rq->queuelist;
- }
-
- cfqd->last_sector = last;
cfqq->next_crq = cfq_find_next_crq(cfqd, cfqq, crq);
-
- cfq_del_crq_rb(crq);
- cfq_remove_merge_hints(q, crq);
-
- cfq_mark_crq_in_flight(crq);
- cfq_clear_crq_requeued(crq);
-
+ cfq_remove_request(crq->request);
cfqq->on_dispatch[cfq_crq_is_sync(crq)]++;
- list_add_tail(&crq->request->queuelist, entry);
+ elv_dispatch_sort(q, crq->request);
}
/*
@@ -1159,7 +1057,7 @@ __cfq_dispatch_requests(struct cfq_data *cfqd, struct cfq_queue *cfqq,
/*
* finally, insert request into driver dispatch list
*/
- cfq_dispatch_sort(cfqd->queue, crq);
+ cfq_dispatch_insert(cfqd->queue, crq);
cfqd->dispatch_slice++;
dispatched++;
@@ -1194,7 +1092,7 @@ __cfq_dispatch_requests(struct cfq_data *cfqd, struct cfq_queue *cfqq,
}
static int
-cfq_dispatch_requests(request_queue_t *q, int max_dispatch, int force)
+cfq_dispatch_requests(request_queue_t *q, int force)
{
struct cfq_data *cfqd = q->elevator->elevator_data;
struct cfq_queue *cfqq;
@@ -1204,12 +1102,25 @@ cfq_dispatch_requests(request_queue_t *q, int max_dispatch, int force)
cfqq = cfq_select_queue(cfqd, force);
if (cfqq) {
+ int max_dispatch;
+
+ /*
+ * if idle window is disabled, allow queue buildup
+ */
+ if (!cfq_cfqq_idle_window(cfqq) &&
+ cfqd->rq_in_driver >= cfqd->cfq_max_depth)
+ return 0;
+
cfq_clear_cfqq_must_dispatch(cfqq);
cfq_clear_cfqq_wait_request(cfqq);
del_timer(&cfqd->idle_slice_timer);
- if (cfq_class_idle(cfqq))
- max_dispatch = 1;
+ if (!force) {
+ max_dispatch = cfqd->cfq_quantum;
+ if (cfq_class_idle(cfqq))
+ max_dispatch = 1;
+ } else
+ max_dispatch = INT_MAX;
return __cfq_dispatch_requests(cfqd, cfqq, max_dispatch);
}
@@ -1217,93 +1128,6 @@ cfq_dispatch_requests(request_queue_t *q, int max_dispatch, int force)
return 0;
}
-static inline void cfq_account_dispatch(struct cfq_rq *crq)
-{
- struct cfq_queue *cfqq = crq->cfq_queue;
- struct cfq_data *cfqd = cfqq->cfqd;
-
- if (unlikely(!blk_fs_request(crq->request)))
- return;
-
- /*
- * accounted bit is necessary since some drivers will call
- * elv_next_request() many times for the same request (eg ide)
- */
- if (cfq_crq_in_driver(crq))
- return;
-
- cfq_mark_crq_in_driver(crq);
- cfqd->rq_in_driver++;
-}
-
-static inline void
-cfq_account_completion(struct cfq_queue *cfqq, struct cfq_rq *crq)
-{
- struct cfq_data *cfqd = cfqq->cfqd;
- unsigned long now;
-
- if (!cfq_crq_in_driver(crq))
- return;
-
- now = jiffies;
-
- WARN_ON(!cfqd->rq_in_driver);
- cfqd->rq_in_driver--;
-
- if (!cfq_class_idle(cfqq))
- cfqd->last_end_request = now;
-
- if (!cfq_cfqq_dispatched(cfqq)) {
- if (cfq_cfqq_on_rr(cfqq)) {
- cfqq->service_last = now;
- cfq_resort_rr_list(cfqq, 0);
- }
- if (cfq_cfqq_expired(cfqq)) {
- __cfq_slice_expired(cfqd, cfqq, 0);
- cfq_schedule_dispatch(cfqd);
- }
- }
-
- if (cfq_crq_is_sync(crq))
- crq->io_context->last_end_request = now;
-}
-
-static struct request *cfq_next_request(request_queue_t *q)
-{
- struct cfq_data *cfqd = q->elevator->elevator_data;
- struct request *rq;
-
- if (!list_empty(&q->queue_head)) {
- struct cfq_rq *crq;
-dispatch:
- rq = list_entry_rq(q->queue_head.next);
-
- crq = RQ_DATA(rq);
- if (crq) {
- struct cfq_queue *cfqq = crq->cfq_queue;
-
- /*
- * if idle window is disabled, allow queue buildup
- */
- if (!cfq_crq_in_driver(crq) &&
- !cfq_cfqq_idle_window(cfqq) &&
- !blk_barrier_rq(rq) &&
- cfqd->rq_in_driver >= cfqd->cfq_max_depth)
- return NULL;
-
- cfq_remove_merge_hints(q, crq);
- cfq_account_dispatch(crq);
- }
-
- return rq;
- }
-
- if (cfq_dispatch_requests(q, cfqd->cfq_quantum, 0))
- goto dispatch;
-
- return NULL;
-}
-
/*
* task holds one reference to the queue, dropped when task exits. each crq
* in-flight on this queue also holds a reference, dropped when crq is freed.
@@ -1816,8 +1640,9 @@ cfq_crq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
}
}
-static void cfq_enqueue(struct cfq_data *cfqd, struct request *rq)
+static void cfq_insert_request(request_queue_t *q, struct request *rq)
{
+ struct cfq_data *cfqd = q->elevator->elevator_data;
struct cfq_rq *crq = RQ_DATA(rq);
struct cfq_queue *cfqq = crq->cfq_queue;
@@ -1827,66 +1652,43 @@ static void cfq_enqueue(struct cfq_data *cfqd, struct request *rq)
list_add_tail(&rq->queuelist, &cfqq->fifo);
- if (rq_mergeable(rq)) {
+ if (rq_mergeable(rq))
cfq_add_crq_hash(cfqd, crq);
- if (!cfqd->queue->last_merge)
- cfqd->queue->last_merge = rq;
- }
-
cfq_crq_enqueued(cfqd, cfqq, crq);
}
-static void
-cfq_insert_request(request_queue_t *q, struct request *rq, int where)
-{
- struct cfq_data *cfqd = q->elevator->elevator_data;
-
- switch (where) {
- case ELEVATOR_INSERT_BACK:
- while (cfq_dispatch_requests(q, INT_MAX, 1))
- ;
- list_add_tail(&rq->queuelist, &q->queue_head);
- /*
- * If we were idling with pending requests on
- * inactive cfqqs, force dispatching will
- * remove the idle timer and the queue won't
- * be kicked by __make_request() afterward.
- * Kick it here.
- */
- cfq_schedule_dispatch(cfqd);
- break;
- case ELEVATOR_INSERT_FRONT:
- list_add(&rq->queuelist, &q->queue_head);
- break;
- case ELEVATOR_INSERT_SORT:
- BUG_ON(!blk_fs_request(rq));
- cfq_enqueue(cfqd, rq);
- break;
- default:
- printk("%s: bad insert point %d\n", __FUNCTION__,where);
- return;
- }
-}
-
static void cfq_completed_request(request_queue_t *q, struct request *rq)
{
struct cfq_rq *crq = RQ_DATA(rq);
- struct cfq_queue *cfqq;
+ struct cfq_queue *cfqq = crq->cfq_queue;
+ struct cfq_data *cfqd = cfqq->cfqd;
+ const int sync = cfq_crq_is_sync(crq);
+ unsigned long now;
- if (unlikely(!blk_fs_request(rq)))
- return;
+ now = jiffies;
- cfqq = crq->cfq_queue;
+ WARN_ON(!cfqd->rq_in_driver);
+ WARN_ON(!cfqq->on_dispatch[sync]);
+ cfqd->rq_in_driver--;
+ cfqq->on_dispatch[sync]--;
- if (cfq_crq_in_flight(crq)) {
- const int sync = cfq_crq_is_sync(crq);
+ if (!cfq_class_idle(cfqq))
+ cfqd->last_end_request = now;
- WARN_ON(!cfqq->on_dispatch[sync]);
- cfqq->on_dispatch[sync]--;
+ if (!cfq_cfqq_dispatched(cfqq)) {
+ if (cfq_cfqq_on_rr(cfqq)) {
+ cfqq->service_last = now;
+ cfq_resort_rr_list(cfqq, 0);
+ }
+ if (cfq_cfqq_expired(cfqq)) {
+ __cfq_slice_expired(cfqd, cfqq, 0);
+ cfq_schedule_dispatch(cfqd);
+ }
}
- cfq_account_completion(cfqq, crq);
+ if (cfq_crq_is_sync(crq))
+ crq->io_context->last_end_request = now;
}
static struct request *
@@ -2118,9 +1920,6 @@ cfq_set_request(request_queue_t *q, struct request *rq, struct bio *bio,
INIT_HLIST_NODE(&crq->hash);
crq->cfq_queue = cfqq;
crq->io_context = cic;
- cfq_clear_crq_in_flight(crq);
- cfq_clear_crq_in_driver(crq);
- cfq_clear_crq_requeued(crq);
if (rw == READ || process_sync(tsk))
cfq_mark_crq_is_sync(crq);
@@ -2201,7 +2000,7 @@ static void cfq_idle_slice_timer(unsigned long data)
* only expire and reinvoke request handler, if there are
* other queues with pending requests
*/
- if (!cfq_pending_requests(cfqd)) {
+ if (!cfqd->busy_queues) {
cfqd->idle_slice_timer.expires = min(now + cfqd->cfq_slice_idle, cfqq->slice_end);
add_timer(&cfqd->idle_slice_timer);
goto out_cont;
@@ -2576,10 +2375,9 @@ static struct elevator_type iosched_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_dispatch_fn = cfq_dispatch_requests,
.elevator_add_req_fn = cfq_insert_request,
- .elevator_remove_req_fn = cfq_remove_request,
- .elevator_requeue_req_fn = cfq_requeue_request,
+ .elevator_activate_req_fn = cfq_activate_request,
.elevator_deactivate_req_fn = cfq_deactivate_request,
.elevator_queue_empty_fn = cfq_queue_empty,
.elevator_completed_req_fn = cfq_completed_request,
diff --git a/drivers/block/deadline-iosched.c b/drivers/block/deadline-iosched.c
index 753546b..7929471 100644
--- a/drivers/block/deadline-iosched.c
+++ b/drivers/block/deadline-iosched.c
@@ -50,7 +50,6 @@ struct deadline_data {
* 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 */
@@ -113,15 +112,6 @@ static inline void deadline_del_drq_hash(struct deadline_rq *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)
{
@@ -239,10 +229,9 @@ deadline_del_drq_rb(struct deadline_data *dd, struct deadline_rq *drq)
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);
- }
+ BUG_ON(!ON_RB(&drq->rb_node));
+ rb_erase(&drq->rb_node, DRQ_RB_ROOT(dd, drq));
+ RB_CLEAR(&drq->rb_node);
}
static struct request *
@@ -286,7 +275,7 @@ deadline_find_first_drq(struct deadline_data *dd, int data_dir)
/*
* add drq to rbtree and fifo
*/
-static inline void
+static void
deadline_add_request(struct request_queue *q, struct request *rq)
{
struct deadline_data *dd = q->elevator->elevator_data;
@@ -301,12 +290,8 @@ deadline_add_request(struct request_queue *q, struct request *rq)
drq->expires = jiffies + dd->fifo_expire[data_dir];
list_add_tail(&drq->fifo, &dd->fifo_list[data_dir]);
- if (rq_mergeable(rq)) {
+ if (rq_mergeable(rq))
deadline_add_drq_hash(dd, drq);
-
- if (!q->last_merge)
- q->last_merge = rq;
- }
}
/*
@@ -315,14 +300,11 @@ deadline_add_request(struct request_queue *q, struct request *rq)
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;
- 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);
- }
+ list_del_init(&drq->fifo);
+ deadline_del_drq_rb(dd, drq);
+ deadline_del_drq_hash(drq);
}
static int
@@ -333,15 +315,6 @@ deadline_merge(request_queue_t *q, struct request **req, struct bio *bio)
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);
@@ -373,8 +346,6 @@ deadline_merge(request_queue_t *q, struct request **req, struct bio *bio)
return ELEVATOR_NO_MERGE;
out:
- q->last_merge = __rq;
-out_insert:
if (ret)
deadline_hot_drq_hash(dd, RQ_DATA(__rq));
*req = __rq;
@@ -399,8 +370,6 @@ static void deadline_merged_request(request_queue_t *q, struct request *req)
deadline_del_drq_rb(dd, drq);
deadline_add_drq_rb(dd, drq);
}
-
- q->last_merge = req;
}
static void
@@ -452,7 +421,7 @@ 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);
+ elv_dispatch_add_tail(q, drq->request);
}
/*
@@ -502,8 +471,9 @@ static inline int deadline_check_fifo(struct deadline_data *dd, int ddir)
* deadline_dispatch_requests selects the best request according to
* read/write expire, fifo_batch, etc
*/
-static int deadline_dispatch_requests(struct deadline_data *dd)
+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;
@@ -597,65 +567,12 @@ dispatch_request:
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;
+ return list_empty(&dd->fifo_list[WRITE])
+ && list_empty(&dd->fifo_list[READ]);
}
static struct request *
@@ -733,7 +650,6 @@ static int deadline_init_queue(request_queue_t *q, elevator_t *e)
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;
@@ -748,10 +664,8 @@ 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;
- }
+ mempool_free(drq, dd->drq_pool);
+ rq->elevator_private = NULL;
}
static int
@@ -917,9 +831,8 @@ static struct elevator_type iosched_deadline = {
.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_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,
diff --git a/drivers/block/elevator.c b/drivers/block/elevator.c
index 4f69d22..3b8099c 100644
--- a/drivers/block/elevator.c
+++ b/drivers/block/elevator.c
@@ -83,15 +83,6 @@ inline int elv_try_merge(struct request *__rq, struct bio *bio)
}
EXPORT_SYMBOL(elv_try_merge);
-inline int elv_try_last_merge(request_queue_t *q, struct bio *bio)
-{
- if (q->last_merge)
- return elv_try_merge(q->last_merge, bio);
-
- return ELEVATOR_NO_MERGE;
-}
-EXPORT_SYMBOL(elv_try_last_merge);
-
static struct elevator_type *elevator_find(const char *name)
{
struct elevator_type *e = NULL;
@@ -143,6 +134,8 @@ static int elevator_attach(request_queue_t *q, struct elevator_type *e,
INIT_LIST_HEAD(&q->queue_head);
q->last_merge = NULL;
q->elevator = eq;
+ q->end_sector = 0;
+ q->boundary_rq = NULL;
if (eq->ops->elevator_init_fn)
ret = eq->ops->elevator_init_fn(q, eq);
@@ -225,9 +218,52 @@ void elevator_exit(elevator_t *e)
kfree(e);
}
+/*
+ * Insert rq into dispatch queue of q. Queue lock must be held on
+ * entry. If sort != 0, rq is sort-inserted; otherwise, rq will be
+ * appended to the dispatch queue. To be used by specific elevators.
+ */
+void elv_dispatch_sort(request_queue_t *q, struct request *rq)
+{
+ sector_t boundary;
+ struct list_head *entry;
+
+ if (q->last_merge == rq)
+ q->last_merge = NULL;
+
+ boundary = q->end_sector;
+
+ list_for_each_prev(entry, &q->queue_head) {
+ struct request *pos = list_entry_rq(entry);
+
+ if (pos->flags & (REQ_SOFTBARRIER|REQ_HARDBARRIER|REQ_STARTED))
+ break;
+ if (rq->sector >= boundary) {
+ if (pos->sector < boundary)
+ continue;
+ } else {
+ if (pos->sector >= boundary)
+ break;
+ }
+ if (rq->sector >= pos->sector)
+ break;
+ }
+
+ list_add(&rq->queuelist, entry);
+}
+
int elv_merge(request_queue_t *q, struct request **req, struct bio *bio)
{
elevator_t *e = q->elevator;
+ int ret;
+
+ if (q->last_merge) {
+ ret = elv_try_merge(q->last_merge, bio);
+ if (ret != ELEVATOR_NO_MERGE) {
+ *req = q->last_merge;
+ return ret;
+ }
+ }
if (e->ops->elevator_merge_fn)
return e->ops->elevator_merge_fn(q, req, bio);
@@ -241,6 +277,8 @@ void elv_merged_request(request_queue_t *q, struct request *rq)
if (e->ops->elevator_merged_fn)
e->ops->elevator_merged_fn(q, rq);
+
+ q->last_merge = rq;
}
void elv_merge_requests(request_queue_t *q, struct request *rq,
@@ -248,20 +286,13 @@ void elv_merge_requests(request_queue_t *q, struct request *rq,
{
elevator_t *e = q->elevator;
- if (q->last_merge == next)
- q->last_merge = NULL;
-
if (e->ops->elevator_merge_req_fn)
e->ops->elevator_merge_req_fn(q, rq, next);
+
+ q->last_merge = rq;
}
-/*
- * For careful internal use by the block layer. Essentially the same as
- * a requeue in that it tells the io scheduler that this request is not
- * active in the driver or hardware anymore, but we don't want the request
- * added back to the scheduler. Function is not exported.
- */
-void elv_deactivate_request(request_queue_t *q, struct request *rq)
+void elv_requeue_request(request_queue_t *q, struct request *rq)
{
elevator_t *e = q->elevator;
@@ -269,19 +300,14 @@ void elv_deactivate_request(request_queue_t *q, struct request *rq)
* it already went through dequeue, we need to decrement the
* in_flight count again
*/
- if (blk_account_rq(rq))
+ if (blk_account_rq(rq)) {
q->in_flight--;
+ if (blk_sorted_rq(rq) && e->ops->elevator_deactivate_req_fn)
+ e->ops->elevator_deactivate_req_fn(q, rq);
+ }
rq->flags &= ~REQ_STARTED;
- if (e->ops->elevator_deactivate_req_fn)
- e->ops->elevator_deactivate_req_fn(q, rq);
-}
-
-void elv_requeue_request(request_queue_t *q, struct request *rq)
-{
- elv_deactivate_request(q, rq);
-
/*
* if this is the flush, requeue the original instead and drop the flush
*/
@@ -290,55 +316,91 @@ void elv_requeue_request(request_queue_t *q, struct request *rq)
rq = rq->end_io_data;
}
- /*
- * the request is prepped and may have some resources allocated.
- * allowing unprepped requests to pass this one may cause resource
- * deadlock. turn on softbarrier.
- */
- rq->flags |= REQ_SOFTBARRIER;
-
- /*
- * if iosched has an explicit requeue hook, then use that. otherwise
- * just put the request at the front of the queue
- */
- if (q->elevator->ops->elevator_requeue_req_fn)
- q->elevator->ops->elevator_requeue_req_fn(q, rq);
- else
- __elv_add_request(q, rq, ELEVATOR_INSERT_FRONT, 0);
+ __elv_add_request(q, rq, ELEVATOR_INSERT_FRONT, 0);
}
void __elv_add_request(request_queue_t *q, struct request *rq, int where,
int plug)
{
- /*
- * barriers implicitly indicate back insertion
- */
- if (rq->flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER) &&
- where == ELEVATOR_INSERT_SORT)
- where = ELEVATOR_INSERT_BACK;
+ if (rq->flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER)) {
+ /*
+ * barriers implicitly indicate back insertion
+ */
+ if (where == ELEVATOR_INSERT_SORT)
+ where = ELEVATOR_INSERT_BACK;
+
+ /*
+ * this request is scheduling boundary, update end_sector
+ */
+ if (blk_fs_request(rq)) {
+ q->end_sector = rq_end_sector(rq);
+ q->boundary_rq = rq;
+ }
+ }
if (plug)
blk_plug_device(q);
rq->q = q;
- if (!test_bit(QUEUE_FLAG_DRAIN, &q->queue_flags)) {
- q->elevator->ops->elevator_add_req_fn(q, rq, where);
-
- if (blk_queue_plugged(q)) {
- int nrq = q->rq.count[READ] + q->rq.count[WRITE]
- - q->in_flight;
-
- if (nrq >= q->unplug_thresh)
- __generic_unplug_device(q);
- }
- } else
+ if (unlikely(test_bit(QUEUE_FLAG_DRAIN, &q->queue_flags))) {
/*
* if drain is set, store the request "locally". when the drain
* is finished, the requests will be handed ordered to the io
* scheduler
*/
list_add_tail(&rq->queuelist, &q->drain_list);
+ return;
+ }
+
+ switch (where) {
+ case ELEVATOR_INSERT_FRONT:
+ rq->flags |= REQ_SOFTBARRIER;
+
+ list_add(&rq->queuelist, &q->queue_head);
+ break;
+
+ case ELEVATOR_INSERT_BACK:
+ rq->flags |= REQ_SOFTBARRIER;
+
+ while (q->elevator->ops->elevator_dispatch_fn(q, 1))
+ ;
+ list_add_tail(&rq->queuelist, &q->queue_head);
+ /*
+ * We kick the queue here for the following reasons.
+ * - The elevator might have returned NULL previously
+ * to delay requests and returned them now. As the
+ * queue wasn't empty before this request, ll_rw_blk
+ * won't run the queue on return, resulting in hang.
+ * - Usually, back inserted requests won't be merged
+ * with anything. There's no point in delaying queue
+ * processing.
+ */
+ blk_remove_plug(q);
+ q->request_fn(q);
+ break;
+
+ case ELEVATOR_INSERT_SORT:
+ BUG_ON(!blk_fs_request(rq));
+ rq->flags |= REQ_SORTED;
+ q->elevator->ops->elevator_add_req_fn(q, rq);
+ if (q->last_merge == NULL && rq_mergeable(rq))
+ q->last_merge = rq;
+ break;
+
+ default:
+ printk(KERN_ERR "%s: bad insertion point %d\n",
+ __FUNCTION__, where);
+ BUG();
+ }
+
+ if (blk_queue_plugged(q)) {
+ int nrq = q->rq.count[READ] + q->rq.count[WRITE]
+ - q->in_flight;
+
+ if (nrq >= q->unplug_thresh)
+ __generic_unplug_device(q);
+ }
}
void elv_add_request(request_queue_t *q, struct request *rq, int where,
@@ -353,13 +415,19 @@ void elv_add_request(request_queue_t *q, struct request *rq, int where,
static inline struct request *__elv_next_request(request_queue_t *q)
{
- struct request *rq = q->elevator->ops->elevator_next_req_fn(q);
+ struct request *rq;
+
+ if (unlikely(list_empty(&q->queue_head) &&
+ !q->elevator->ops->elevator_dispatch_fn(q, 0)))
+ return NULL;
+
+ rq = list_entry_rq(q->queue_head.next);
/*
* if this is a barrier write and the device has to issue a
* flush sequence to support it, check how far we are
*/
- if (rq && blk_fs_request(rq) && blk_barrier_rq(rq)) {
+ if (blk_fs_request(rq) && blk_barrier_rq(rq)) {
BUG_ON(q->ordered == QUEUE_ORDERED_NONE);
if (q->ordered == QUEUE_ORDERED_FLUSH &&
@@ -376,15 +444,30 @@ struct request *elv_next_request(request_queue_t *q)
int ret;
while ((rq = __elv_next_request(q)) != NULL) {
- /*
- * just mark as started even if we don't start it, a request
- * that has been delayed should not be passed by new incoming
- * requests
- */
- rq->flags |= REQ_STARTED;
+ if (!(rq->flags & REQ_STARTED)) {
+ elevator_t *e = q->elevator;
+
+ /*
+ * This is the first time the device driver
+ * sees this request (possibly after
+ * requeueing). Notify IO scheduler.
+ */
+ if (blk_sorted_rq(rq) &&
+ e->ops->elevator_activate_req_fn)
+ e->ops->elevator_activate_req_fn(q, rq);
- if (rq == q->last_merge)
- q->last_merge = NULL;
+ /*
+ * just mark as started even if we don't start
+ * it, a request that has been delayed should
+ * not be passed by new incoming requests
+ */
+ rq->flags |= REQ_STARTED;
+ }
+
+ if (!q->boundary_rq || q->boundary_rq == rq) {
+ q->end_sector = rq_end_sector(rq);
+ q->boundary_rq = NULL;
+ }
if ((rq->flags & REQ_DONTPREP) || !q->prep_rq_fn)
break;
@@ -396,9 +479,9 @@ struct request *elv_next_request(request_queue_t *q)
/*
* the request may have been (partially) prepped.
* we need to keep this request in the front to
- * avoid resource deadlock. turn on softbarrier.
+ * avoid resource deadlock. REQ_STARTED will
+ * prevent other fs requests from passing this one.
*/
- rq->flags |= REQ_SOFTBARRIER;
rq = NULL;
break;
} else if (ret == BLKPREP_KILL) {
@@ -421,42 +504,32 @@ struct request *elv_next_request(request_queue_t *q)
return rq;
}
-void elv_remove_request(request_queue_t *q, struct request *rq)
+void elv_dequeue_request(request_queue_t *q, struct request *rq)
{
- elevator_t *e = q->elevator;
+ BUG_ON(list_empty(&rq->queuelist));
+
+ list_del_init(&rq->queuelist);
/*
* the time frame between a request being removed from the lists
* and to it is freed is accounted as io that is in progress at
- * the driver side. note that we only account requests that the
- * driver has seen (REQ_STARTED set), to avoid false accounting
- * for request-request merges
+ * the driver side.
*/
if (blk_account_rq(rq))
q->in_flight++;
-
- /*
- * the main clearing point for q->last_merge is on retrieval of
- * request by driver (it calls elv_next_request()), but it _can_
- * also happen here if a request is added to the queue but later
- * deleted without ever being given to driver (merged with another
- * request).
- */
- if (rq == q->last_merge)
- q->last_merge = NULL;
-
- if (e->ops->elevator_remove_req_fn)
- e->ops->elevator_remove_req_fn(q, rq);
}
int elv_queue_empty(request_queue_t *q)
{
elevator_t *e = q->elevator;
+ if (!list_empty(&q->queue_head))
+ return 0;
+
if (e->ops->elevator_queue_empty_fn)
return e->ops->elevator_queue_empty_fn(q);
- return list_empty(&q->queue_head);
+ return 1;
}
struct request *elv_latter_request(request_queue_t *q, struct request *rq)
@@ -528,11 +601,11 @@ void elv_completed_request(request_queue_t *q, struct request *rq)
/*
* request is released from the driver, io must be done
*/
- if (blk_account_rq(rq))
+ if (blk_account_rq(rq)) {
q->in_flight--;
-
- if (e->ops->elevator_completed_req_fn)
- e->ops->elevator_completed_req_fn(q, rq);
+ if (blk_sorted_rq(rq) && e->ops->elevator_completed_req_fn)
+ e->ops->elevator_completed_req_fn(q, rq);
+ }
}
int elv_register_queue(struct request_queue *q)
@@ -705,11 +778,12 @@ ssize_t elv_iosched_show(request_queue_t *q, char *name)
return len;
}
+EXPORT_SYMBOL(elv_dispatch_sort);
EXPORT_SYMBOL(elv_add_request);
EXPORT_SYMBOL(__elv_add_request);
EXPORT_SYMBOL(elv_requeue_request);
EXPORT_SYMBOL(elv_next_request);
-EXPORT_SYMBOL(elv_remove_request);
+EXPORT_SYMBOL(elv_dequeue_request);
EXPORT_SYMBOL(elv_queue_empty);
EXPORT_SYMBOL(elv_completed_request);
EXPORT_SYMBOL(elevator_exit);
diff --git a/drivers/block/ll_rw_blk.c b/drivers/block/ll_rw_blk.c
index ac31ea1..c4f1862 100644
--- a/drivers/block/ll_rw_blk.c
+++ b/drivers/block/ll_rw_blk.c
@@ -353,6 +353,8 @@ static void blk_pre_flush_end_io(struct request *flush_rq)
struct request *rq = flush_rq->end_io_data;
request_queue_t *q = rq->q;
+ elv_completed_request(q, flush_rq);
+
rq->flags |= REQ_BAR_PREFLUSH;
if (!flush_rq->errors)
@@ -369,6 +371,8 @@ static void blk_post_flush_end_io(struct request *flush_rq)
struct request *rq = flush_rq->end_io_data;
request_queue_t *q = rq->q;
+ elv_completed_request(q, flush_rq);
+
rq->flags |= REQ_BAR_POSTFLUSH;
q->end_flush_fn(q, flush_rq);
@@ -408,8 +412,6 @@ struct request *blk_start_pre_flush(request_queue_t *q, struct request *rq)
if (!list_empty(&rq->queuelist))
blkdev_dequeue_request(rq);
- elv_deactivate_request(q, rq);
-
flush_rq->end_io_data = rq;
flush_rq->end_io = blk_pre_flush_end_io;
@@ -1040,6 +1042,7 @@ EXPORT_SYMBOL(blk_queue_invalidate_tags);
static char *rq_flags[] = {
"REQ_RW",
"REQ_FAILFAST",
+ "REQ_SORTED",
"REQ_SOFTBARRIER",
"REQ_HARDBARRIER",
"REQ_CMD",
@@ -2456,6 +2459,8 @@ static void __blk_put_request(request_queue_t *q, struct request *req)
if (unlikely(--req->ref_count))
return;
+ elv_completed_request(q, req);
+
req->rq_status = RQ_INACTIVE;
req->rl = NULL;
@@ -2466,8 +2471,6 @@ static void __blk_put_request(request_queue_t *q, struct request *req)
if (rl) {
int rw = rq_data_dir(req);
- elv_completed_request(q, req);
-
BUG_ON(!list_empty(&req->queuelist));
blk_free_request(q, req);
@@ -2477,14 +2480,14 @@ static void __blk_put_request(request_queue_t *q, struct request *req)
void blk_put_request(struct request *req)
{
+ unsigned long flags;
+ request_queue_t *q = req->q;
+
/*
- * if req->rl isn't set, this request didnt originate from the
- * block layer, so it's safe to just disregard it
+ * Gee, IDE calls in w/ NULL q. Fix IDE and remove the
+ * following if (q) test.
*/
- if (req->rl) {
- unsigned long flags;
- request_queue_t *q = req->q;
-
+ if (q) {
spin_lock_irqsave(q->queue_lock, flags);
__blk_put_request(q, req);
spin_unlock_irqrestore(q->queue_lock, flags);
diff --git a/drivers/block/noop-iosched.c b/drivers/block/noop-iosched.c
index b1730b6..f56b8ed 100644
--- a/drivers/block/noop-iosched.c
+++ b/drivers/block/noop-iosched.c
@@ -7,57 +7,19 @@
#include <linux/module.h>
#include <linux/init.h>
-/*
- * See if we can find a request that this buffer can be coalesced with.
- */
-static int elevator_noop_merge(request_queue_t *q, struct request **req,
- struct bio *bio)
-{
- int ret;
-
- ret = elv_try_last_merge(q, bio);
- if (ret != ELEVATOR_NO_MERGE)
- *req = q->last_merge;
-
- return ret;
-}
-
-static void elevator_noop_merge_requests(request_queue_t *q, struct request *req,
- struct request *next)
-{
- list_del_init(&next->queuelist);
-}
-
-static void elevator_noop_add_request(request_queue_t *q, struct request *rq,
- int where)
+static void elevator_noop_add_request(request_queue_t *q, struct request *rq)
{
- if (where == ELEVATOR_INSERT_FRONT)
- list_add(&rq->queuelist, &q->queue_head);
- else
- list_add_tail(&rq->queuelist, &q->queue_head);
-
- /*
- * new merges must not precede this barrier
- */
- if (rq->flags & REQ_HARDBARRIER)
- q->last_merge = NULL;
- else if (!q->last_merge)
- q->last_merge = rq;
+ elv_dispatch_add_tail(q, rq);
}
-static struct request *elevator_noop_next_request(request_queue_t *q)
+static int elevator_noop_dispatch(request_queue_t *q, int force)
{
- if (!list_empty(&q->queue_head))
- return list_entry_rq(q->queue_head.next);
-
- return NULL;
+ return 0;
}
static struct elevator_type elevator_noop = {
.ops = {
- .elevator_merge_fn = elevator_noop_merge,
- .elevator_merge_req_fn = elevator_noop_merge_requests,
- .elevator_next_req_fn = elevator_noop_next_request,
+ .elevator_dispatch_fn = elevator_noop_dispatch,
.elevator_add_req_fn = elevator_noop_add_request,
},
.elevator_name = "noop",
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 1afbdb2..fffe163 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -203,6 +203,7 @@ struct request {
enum rq_flag_bits {
__REQ_RW, /* not set, read. set, write */
__REQ_FAILFAST, /* no low level driver retries */
+ __REQ_SORTED, /* elevator knows about this request */
__REQ_SOFTBARRIER, /* may not be passed by ioscheduler */
__REQ_HARDBARRIER, /* may not be passed by drive either */
__REQ_CMD, /* is a regular fs rw request */
@@ -235,6 +236,7 @@ enum rq_flag_bits {
#define REQ_RW (1 << __REQ_RW)
#define REQ_FAILFAST (1 << __REQ_FAILFAST)
+#define REQ_SORTED (1 << __REQ_SORTED)
#define REQ_SOFTBARRIER (1 << __REQ_SOFTBARRIER)
#define REQ_HARDBARRIER (1 << __REQ_HARDBARRIER)
#define REQ_CMD (1 << __REQ_CMD)
@@ -333,6 +335,12 @@ struct request_queue
end_flush_fn *end_flush_fn;
/*
+ * Dispatch queue sorting
+ */
+ sector_t end_sector;
+ struct request *boundary_rq;
+
+ /*
* Auto-unplugging state
*/
struct timer_list unplug_timer;
@@ -454,6 +462,7 @@ enum {
#define blk_pm_request(rq) \
((rq)->flags & (REQ_PM_SUSPEND | REQ_PM_RESUME))
+#define blk_sorted_rq(rq) ((rq)->flags & REQ_SORTED)
#define blk_barrier_rq(rq) ((rq)->flags & REQ_HARDBARRIER)
#define blk_barrier_preflush(rq) ((rq)->flags & REQ_BAR_PREFLUSH)
#define blk_barrier_postflush(rq) ((rq)->flags & REQ_BAR_POSTFLUSH)
@@ -611,12 +620,21 @@ extern void end_request(struct request *req, int uptodate);
static inline void blkdev_dequeue_request(struct request *req)
{
- BUG_ON(list_empty(&req->queuelist));
+ elv_dequeue_request(req->q, req);
+}
- list_del_init(&req->queuelist);
+/*
+ * This should be in elevator.h, but that requires pulling in rq and q
+ */
+static inline void elv_dispatch_add_tail(struct request_queue *q,
+ struct request *rq)
+{
+ if (q->last_merge == rq)
+ q->last_merge = NULL;
- if (req->rl)
- elv_remove_request(req->q, req);
+ q->end_sector = rq_end_sector(rq);
+ q->boundary_rq = rq;
+ list_add_tail(&rq->queuelist, &q->queue_head);
}
/*
diff --git a/include/linux/elevator.h b/include/linux/elevator.h
index ed93125..a74c27e 100644
--- a/include/linux/elevator.h
+++ b/include/linux/elevator.h
@@ -8,18 +8,17 @@ typedef void (elevator_merge_req_fn) (request_queue_t *, struct request *, struc
typedef void (elevator_merged_fn) (request_queue_t *, struct request *);
-typedef struct request *(elevator_next_req_fn) (request_queue_t *);
+typedef int (elevator_dispatch_fn) (request_queue_t *, int);
-typedef void (elevator_add_req_fn) (request_queue_t *, struct request *, int);
+typedef void (elevator_add_req_fn) (request_queue_t *, struct request *);
typedef int (elevator_queue_empty_fn) (request_queue_t *);
-typedef void (elevator_remove_req_fn) (request_queue_t *, struct request *);
-typedef void (elevator_requeue_req_fn) (request_queue_t *, struct request *);
typedef struct request *(elevator_request_list_fn) (request_queue_t *, struct request *);
typedef void (elevator_completed_req_fn) (request_queue_t *, struct request *);
typedef int (elevator_may_queue_fn) (request_queue_t *, int, struct bio *);
typedef int (elevator_set_req_fn) (request_queue_t *, struct request *, struct bio *, gfp_t);
typedef void (elevator_put_req_fn) (request_queue_t *, struct request *);
+typedef void (elevator_activate_req_fn) (request_queue_t *, struct request *);
typedef void (elevator_deactivate_req_fn) (request_queue_t *, struct request *);
typedef int (elevator_init_fn) (request_queue_t *, elevator_t *);
@@ -31,10 +30,9 @@ struct elevator_ops
elevator_merged_fn *elevator_merged_fn;
elevator_merge_req_fn *elevator_merge_req_fn;
- elevator_next_req_fn *elevator_next_req_fn;
+ elevator_dispatch_fn *elevator_dispatch_fn;
elevator_add_req_fn *elevator_add_req_fn;
- elevator_remove_req_fn *elevator_remove_req_fn;
- elevator_requeue_req_fn *elevator_requeue_req_fn;
+ elevator_activate_req_fn *elevator_activate_req_fn;
elevator_deactivate_req_fn *elevator_deactivate_req_fn;
elevator_queue_empty_fn *elevator_queue_empty_fn;
@@ -81,15 +79,15 @@ struct elevator_queue
/*
* block elevator interface
*/
+extern void elv_dispatch_sort(request_queue_t *, struct request *);
extern void elv_add_request(request_queue_t *, struct request *, int, int);
extern void __elv_add_request(request_queue_t *, struct request *, int, int);
extern int elv_merge(request_queue_t *, struct request **, struct bio *);
extern void elv_merge_requests(request_queue_t *, struct request *,
struct request *);
extern void elv_merged_request(request_queue_t *, struct request *);
-extern void elv_remove_request(request_queue_t *, struct request *);
+extern void elv_dequeue_request(request_queue_t *, struct request *);
extern void elv_requeue_request(request_queue_t *, struct request *);
-extern void elv_deactivate_request(request_queue_t *, struct request *);
extern int elv_queue_empty(request_queue_t *);
extern struct request *elv_next_request(struct request_queue *q);
extern struct request *elv_former_request(request_queue_t *, struct request *);
@@ -142,4 +140,6 @@ enum {
ELV_MQUEUE_MUST,
};
+#define rq_end_sector(rq) ((rq)->sector + (rq)->nr_sectors)
+
#endif
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