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blk-throttle: dispatch to throtl_data->service_queue.bio_lists[] 

throtl_service_queues will eventually form a tree which is anchored at
throtl_data->service_queue and queue bios will climb the tree to the
top service_queue to be executed.

This patch makes the dispatch paths in blk_throtl_dispatch_work_fn()
and blk_throtl_drain() to dispatch bios to
throtl_data->service_queue.bio_lists[] instead of the on-stack
bio_lists.  This will keep the final dispatch to the top level
service_queue share the same mechanism as dispatches through the rest
of the hierarchy.

As bio's should be issued in a sleepable context,
blk_throtl_dispatch_work_fn() transfers all dispatched bio's from the
service_queue bio_lists[] into an onstack one before dropping
queue_lock and issuing the bio's.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
This commit is contained in:
Tejun Heo 2013-05-14 13:52:35 -07:00
parent 73f0d49a96
commit 651930bc1c
1 changed files with 23 additions and 17 deletions
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40
block/blk-throttle.c
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@ -743,7 +743,7 @@ static void tg_update_disptime(struct throtl_grp *tg,
}
static void tg_dispatch_one_bio(struct throtl_grp *tg, bool rw,
struct bio_list *bl)
struct throtl_service_queue *parent_sq)
{
struct throtl_service_queue *sq = &tg->service_queue;
struct bio *bio;
@ -757,13 +757,14 @@ static void tg_dispatch_one_bio(struct throtl_grp *tg, bool rw,
tg->td->nr_queued[rw]--;
throtl_charge_bio(tg, bio);
bio_list_add(bl, bio);
bio_list_add(&parent_sq->bio_lists[rw], bio);
bio->bi_rw |= REQ_THROTTLED;
throtl_trim_slice(tg, rw);
}
static int throtl_dispatch_tg(struct throtl_grp *tg, struct bio_list *bl)
static int throtl_dispatch_tg(struct throtl_grp *tg,
struct throtl_service_queue *parent_sq)
{
struct throtl_service_queue *sq = &tg->service_queue;
unsigned int nr_reads = 0, nr_writes = 0;
@ -776,7 +777,7 @@ static int throtl_dispatch_tg(struct throtl_grp *tg, struct bio_list *bl)
while ((bio = bio_list_peek(&sq->bio_lists[READ])) &&
tg_may_dispatch(tg, bio, NULL)) {
tg_dispatch_one_bio(tg, bio_data_dir(bio), bl);
tg_dispatch_one_bio(tg, bio_data_dir(bio), parent_sq);
nr_reads++;
if (nr_reads >= max_nr_reads)
@ -786,7 +787,7 @@ static int throtl_dispatch_tg(struct throtl_grp *tg, struct bio_list *bl)
while ((bio = bio_list_peek(&sq->bio_lists[WRITE])) &&
tg_may_dispatch(tg, bio, NULL)) {
tg_dispatch_one_bio(tg, bio_data_dir(bio), bl);
tg_dispatch_one_bio(tg, bio_data_dir(bio), parent_sq);
nr_writes++;
if (nr_writes >= max_nr_writes)
@ -796,8 +797,7 @@ static int throtl_dispatch_tg(struct throtl_grp *tg, struct bio_list *bl)
return nr_reads + nr_writes;
}
static int throtl_select_dispatch(struct throtl_service_queue *parent_sq,
struct bio_list *bl)
static int throtl_select_dispatch(struct throtl_service_queue *parent_sq)
{
unsigned int nr_disp = 0;
@ -813,7 +813,7 @@ static int throtl_select_dispatch(struct throtl_service_queue *parent_sq,
throtl_dequeue_tg(tg, parent_sq);
nr_disp += throtl_dispatch_tg(tg, bl);
nr_disp += throtl_dispatch_tg(tg, parent_sq);
if (sq->nr_queued[0] || sq->nr_queued[1])
tg_update_disptime(tg, parent_sq);
@ -830,11 +830,13 @@ void blk_throtl_dispatch_work_fn(struct work_struct *work)
{
struct throtl_data *td = container_of(to_delayed_work(work),
struct throtl_data, dispatch_work);
struct throtl_service_queue *sq = &td->service_queue;
struct request_queue *q = td->queue;
unsigned int nr_disp = 0;
struct bio_list bio_list_on_stack;
struct bio *bio;
struct blk_plug plug;
int rw;
spin_lock_irq(q->queue_lock);
@ -844,10 +846,15 @@ void blk_throtl_dispatch_work_fn(struct work_struct *work)
td->nr_queued[READ] + td->nr_queued[WRITE],
td->nr_queued[READ], td->nr_queued[WRITE]);
nr_disp = throtl_select_dispatch(&td->service_queue, &bio_list_on_stack);
nr_disp = throtl_select_dispatch(sq);
if (nr_disp)
if (nr_disp) {
for (rw = READ; rw <= WRITE; rw++) {
bio_list_merge(&bio_list_on_stack, &sq->bio_lists[rw]);
bio_list_init(&sq->bio_lists[rw]);
}
throtl_log(td, "bios disp=%u", nr_disp);
}
throtl_schedule_next_dispatch(td);
@ -1156,27 +1163,26 @@ void blk_throtl_drain(struct request_queue *q)
struct throtl_data *td = q->td;
struct throtl_service_queue *parent_sq = &td->service_queue;
struct throtl_grp *tg;
struct bio_list bl;
struct bio *bio;
int rw;
queue_lockdep_assert_held(q);
bio_list_init(&bl);
while ((tg = throtl_rb_first(parent_sq))) {
struct throtl_service_queue *sq = &tg->service_queue;
throtl_dequeue_tg(tg, parent_sq);
while ((bio = bio_list_peek(&sq->bio_lists[READ])))
tg_dispatch_one_bio(tg, bio_data_dir(bio), &bl);
tg_dispatch_one_bio(tg, bio_data_dir(bio), parent_sq);
while ((bio = bio_list_peek(&sq->bio_lists[WRITE])))
tg_dispatch_one_bio(tg, bio_data_dir(bio), &bl);
tg_dispatch_one_bio(tg, bio_data_dir(bio), parent_sq);
}
spin_unlock_irq(q->queue_lock);
while ((bio = bio_list_pop(&bl)))
generic_make_request(bio);
for (rw = READ; rw <= WRITE; rw++)
while ((bio = bio_list_pop(&parent_sq->bio_lists[rw])))
generic_make_request(bio);
spin_lock_irq(q->queue_lock);
}