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authorJens Axboe <jens.axboe@oracle.com>2009-04-06 14:48:01 +0200
committerLinus Torvalds <torvalds@linux-foundation.org>2009-04-06 08:04:53 -0700
commit1faa16d22877f4839bd433547d770c676d1d964c (patch)
tree9a0d50be1ef0358c1f53d7107413100904e7d526 /block
parent0221c81b1b8eb0cbb6b30a0ced52ead32d2b4e4c (diff)
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block: change the request allocation/congestion logic to be sync/async based
This makes sure that we never wait on async IO for sync requests, instead of doing the split on writes vs reads. Signed-off-by: Jens Axboe <jens.axboe@oracle.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'block')
-rw-r--r--block/blk-core.c70
-rw-r--r--block/blk-sysfs.c40
-rw-r--r--block/elevator.c2
3 files changed, 56 insertions, 56 deletions
diff --git a/block/blk-core.c b/block/blk-core.c
index 996ed906d8c..a32b571aaaa 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -484,11 +484,11 @@ static int blk_init_free_list(struct request_queue *q)
{
struct request_list *rl = &q->rq;
- rl->count[READ] = rl->count[WRITE] = 0;
- rl->starved[READ] = rl->starved[WRITE] = 0;
+ rl->count[BLK_RW_SYNC] = rl->count[BLK_RW_ASYNC] = 0;
+ rl->starved[BLK_RW_SYNC] = rl->starved[BLK_RW_ASYNC] = 0;
rl->elvpriv = 0;
- init_waitqueue_head(&rl->wait[READ]);
- init_waitqueue_head(&rl->wait[WRITE]);
+ init_waitqueue_head(&rl->wait[BLK_RW_SYNC]);
+ init_waitqueue_head(&rl->wait[BLK_RW_ASYNC]);
rl->rq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab,
mempool_free_slab, request_cachep, q->node);
@@ -699,18 +699,18 @@ static void ioc_set_batching(struct request_queue *q, struct io_context *ioc)
ioc->last_waited = jiffies;
}
-static void __freed_request(struct request_queue *q, int rw)
+static void __freed_request(struct request_queue *q, int sync)
{
struct request_list *rl = &q->rq;
- if (rl->count[rw] < queue_congestion_off_threshold(q))
- blk_clear_queue_congested(q, rw);
+ if (rl->count[sync] < queue_congestion_off_threshold(q))
+ blk_clear_queue_congested(q, sync);
- if (rl->count[rw] + 1 <= q->nr_requests) {
- if (waitqueue_active(&rl->wait[rw]))
- wake_up(&rl->wait[rw]);
+ if (rl->count[sync] + 1 <= q->nr_requests) {
+ if (waitqueue_active(&rl->wait[sync]))
+ wake_up(&rl->wait[sync]);
- blk_clear_queue_full(q, rw);
+ blk_clear_queue_full(q, sync);
}
}
@@ -718,18 +718,18 @@ static void __freed_request(struct request_queue *q, int rw)
* A request has just been released. Account for it, update the full and
* congestion status, wake up any waiters. Called under q->queue_lock.
*/
-static void freed_request(struct request_queue *q, int rw, int priv)
+static void freed_request(struct request_queue *q, int sync, int priv)
{
struct request_list *rl = &q->rq;
- rl->count[rw]--;
+ rl->count[sync]--;
if (priv)
rl->elvpriv--;
- __freed_request(q, rw);
+ __freed_request(q, sync);
- if (unlikely(rl->starved[rw ^ 1]))
- __freed_request(q, rw ^ 1);
+ if (unlikely(rl->starved[sync ^ 1]))
+ __freed_request(q, sync ^ 1);
}
/*
@@ -743,15 +743,15 @@ static struct request *get_request(struct request_queue *q, int rw_flags,
struct request *rq = NULL;
struct request_list *rl = &q->rq;
struct io_context *ioc = NULL;
- const int rw = rw_flags & 0x01;
+ const bool is_sync = rw_is_sync(rw_flags) != 0;
int may_queue, priv;
may_queue = elv_may_queue(q, rw_flags);
if (may_queue == ELV_MQUEUE_NO)
goto rq_starved;
- if (rl->count[rw]+1 >= queue_congestion_on_threshold(q)) {
- if (rl->count[rw]+1 >= q->nr_requests) {
+ if (rl->count[is_sync]+1 >= queue_congestion_on_threshold(q)) {
+ if (rl->count[is_sync]+1 >= q->nr_requests) {
ioc = current_io_context(GFP_ATOMIC, q->node);
/*
* The queue will fill after this allocation, so set
@@ -759,9 +759,9 @@ static struct request *get_request(struct request_queue *q, int rw_flags,
* This process will be allowed to complete a batch of
* requests, others will be blocked.
*/
- if (!blk_queue_full(q, rw)) {
+ if (!blk_queue_full(q, is_sync)) {
ioc_set_batching(q, ioc);
- blk_set_queue_full(q, rw);
+ blk_set_queue_full(q, is_sync);
} else {
if (may_queue != ELV_MQUEUE_MUST
&& !ioc_batching(q, ioc)) {
@@ -774,7 +774,7 @@ static struct request *get_request(struct request_queue *q, int rw_flags,
}
}
}
- blk_set_queue_congested(q, rw);
+ blk_set_queue_congested(q, is_sync);
}
/*
@@ -782,11 +782,11 @@ static struct request *get_request(struct request_queue *q, int rw_flags,
* limit of requests, otherwise we could have thousands of requests
* allocated with any setting of ->nr_requests
*/
- if (rl->count[rw] >= (3 * q->nr_requests / 2))
+ if (rl->count[is_sync] >= (3 * q->nr_requests / 2))
goto out;
- rl->count[rw]++;
- rl->starved[rw] = 0;
+ rl->count[is_sync]++;
+ rl->starved[is_sync] = 0;
priv = !test_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags);
if (priv)
@@ -804,7 +804,7 @@ static struct request *get_request(struct request_queue *q, int rw_flags,
* wait queue, but this is pretty rare.
*/
spin_lock_irq(q->queue_lock);
- freed_request(q, rw, priv);
+ freed_request(q, is_sync, priv);
/*
* in the very unlikely event that allocation failed and no
@@ -814,8 +814,8 @@ static struct request *get_request(struct request_queue *q, int rw_flags,
* rq mempool into READ and WRITE
*/
rq_starved:
- if (unlikely(rl->count[rw] == 0))
- rl->starved[rw] = 1;
+ if (unlikely(rl->count[is_sync] == 0))
+ rl->starved[is_sync] = 1;
goto out;
}
@@ -829,7 +829,7 @@ rq_starved:
if (ioc_batching(q, ioc))
ioc->nr_batch_requests--;
- trace_block_getrq(q, bio, rw);
+ trace_block_getrq(q, bio, rw_flags & 1);
out:
return rq;
}
@@ -843,7 +843,7 @@ out:
static struct request *get_request_wait(struct request_queue *q, int rw_flags,
struct bio *bio)
{
- const int rw = rw_flags & 0x01;
+ const bool is_sync = rw_is_sync(rw_flags) != 0;
struct request *rq;
rq = get_request(q, rw_flags, bio, GFP_NOIO);
@@ -852,10 +852,10 @@ static struct request *get_request_wait(struct request_queue *q, int rw_flags,
struct io_context *ioc;
struct request_list *rl = &q->rq;
- prepare_to_wait_exclusive(&rl->wait[rw], &wait,
+ prepare_to_wait_exclusive(&rl->wait[is_sync], &wait,
TASK_UNINTERRUPTIBLE);
- trace_block_sleeprq(q, bio, rw);
+ trace_block_sleeprq(q, bio, rw_flags & 1);
__generic_unplug_device(q);
spin_unlock_irq(q->queue_lock);
@@ -871,7 +871,7 @@ static struct request *get_request_wait(struct request_queue *q, int rw_flags,
ioc_set_batching(q, ioc);
spin_lock_irq(q->queue_lock);
- finish_wait(&rl->wait[rw], &wait);
+ finish_wait(&rl->wait[is_sync], &wait);
rq = get_request(q, rw_flags, bio, GFP_NOIO);
};
@@ -1070,14 +1070,14 @@ void __blk_put_request(struct request_queue *q, struct request *req)
* it didn't come out of our reserved rq pools
*/
if (req->cmd_flags & REQ_ALLOCED) {
- int rw = rq_data_dir(req);
+ int is_sync = rq_is_sync(req) != 0;
int priv = req->cmd_flags & REQ_ELVPRIV;
BUG_ON(!list_empty(&req->queuelist));
BUG_ON(!hlist_unhashed(&req->hash));
blk_free_request(q, req);
- freed_request(q, rw, priv);
+ freed_request(q, is_sync, priv);
}
}
EXPORT_SYMBOL_GPL(__blk_put_request);
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index e29ddfc73cf..3ff9bba3379 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -48,28 +48,28 @@ queue_requests_store(struct request_queue *q, const char *page, size_t count)
q->nr_requests = nr;
blk_queue_congestion_threshold(q);
- if (rl->count[READ] >= queue_congestion_on_threshold(q))
- blk_set_queue_congested(q, READ);
- else if (rl->count[READ] < queue_congestion_off_threshold(q))
- blk_clear_queue_congested(q, READ);
-
- if (rl->count[WRITE] >= queue_congestion_on_threshold(q))
- blk_set_queue_congested(q, WRITE);
- else if (rl->count[WRITE] < queue_congestion_off_threshold(q))
- blk_clear_queue_congested(q, WRITE);
-
- if (rl->count[READ] >= q->nr_requests) {
- blk_set_queue_full(q, READ);
- } else if (rl->count[READ]+1 <= q->nr_requests) {
- blk_clear_queue_full(q, READ);
- wake_up(&rl->wait[READ]);
+ if (rl->count[BLK_RW_SYNC] >= queue_congestion_on_threshold(q))
+ blk_set_queue_congested(q, BLK_RW_SYNC);
+ else if (rl->count[BLK_RW_SYNC] < queue_congestion_off_threshold(q))
+ blk_clear_queue_congested(q, BLK_RW_SYNC);
+
+ if (rl->count[BLK_RW_ASYNC] >= queue_congestion_on_threshold(q))
+ blk_set_queue_congested(q, BLK_RW_ASYNC);
+ else if (rl->count[BLK_RW_ASYNC] < queue_congestion_off_threshold(q))
+ blk_clear_queue_congested(q, BLK_RW_ASYNC);
+
+ if (rl->count[BLK_RW_SYNC] >= q->nr_requests) {
+ blk_set_queue_full(q, BLK_RW_SYNC);
+ } else if (rl->count[BLK_RW_SYNC]+1 <= q->nr_requests) {
+ blk_clear_queue_full(q, BLK_RW_SYNC);
+ wake_up(&rl->wait[BLK_RW_SYNC]);
}
- if (rl->count[WRITE] >= q->nr_requests) {
- blk_set_queue_full(q, WRITE);
- } else if (rl->count[WRITE]+1 <= q->nr_requests) {
- blk_clear_queue_full(q, WRITE);
- wake_up(&rl->wait[WRITE]);
+ if (rl->count[BLK_RW_ASYNC] >= q->nr_requests) {
+ blk_set_queue_full(q, BLK_RW_ASYNC);
+ } else if (rl->count[BLK_RW_ASYNC]+1 <= q->nr_requests) {
+ blk_clear_queue_full(q, BLK_RW_ASYNC);
+ wake_up(&rl->wait[BLK_RW_ASYNC]);
}
spin_unlock_irq(q->queue_lock);
return ret;
diff --git a/block/elevator.c b/block/elevator.c
index 98259eda0ef..ca6788a0195 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -677,7 +677,7 @@ void elv_insert(struct request_queue *q, struct request *rq, int where)
}
if (unplug_it && blk_queue_plugged(q)) {
- int nrq = q->rq.count[READ] + q->rq.count[WRITE]
+ int nrq = q->rq.count[BLK_RW_SYNC] + q->rq.count[BLK_RW_ASYNC]
- q->in_flight;
if (nrq >= q->unplug_thresh)