diff mbox series

[RESEND,v6,8/8] blk-throttle: clean up flag 'THROTL_TG_PENDING'

Message ID 20220701093441.885741-9-yukuai1@huaweicloud.com (mailing list archive)
State New, archived
Headers show
Series bugfix and cleanup for blk-throttle | expand

Commit Message

Yu Kuai July 1, 2022, 9:34 a.m. UTC 
From: Yu Kuai <yukuai3@huawei.com>

All related operations are inside 'queue_lock', there is no need to use
the flag, we only need to make sure throtl_enqueue_tg() is called when
the first bio is throttled, and throtl_dequeue_tg() is called when the
last throttled bio is dispatched.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
---
 block/blk-throttle.c | 22 ++++++++--------------
 block/blk-throttle.h |  7 +++----
 2 files changed, 11 insertions(+), 18 deletions(-)

Comments

Tejun Heo July 27, 2022, 6:44 p.m. UTC | #1 
On Fri, Jul 01, 2022 at 05:34:41PM +0800, Yu Kuai wrote:
> From: Yu Kuai <yukuai3@huawei.com>
> 
> All related operations are inside 'queue_lock', there is no need to use
> the flag, we only need to make sure throtl_enqueue_tg() is called when
> the first bio is throttled, and throtl_dequeue_tg() is called when the
> last throttled bio is dispatched.

Ah, okay, so the prev patch was to enable this cleanup. Can you please note
so in the previous patch and also that this doesn't cause any functional
changes?

Thanks.
Yu Kuai July 28, 2022, 11:03 a.m. UTC | #2 
在 2022/07/28 2:44, Tejun Heo 写道:
> On Fri, Jul 01, 2022 at 05:34:41PM +0800, Yu Kuai wrote:
>> From: Yu Kuai <yukuai3@huawei.com>
>>
>> All related operations are inside 'queue_lock', there is no need to use
>> the flag, we only need to make sure throtl_enqueue_tg() is called when
>> the first bio is throttled, and throtl_dequeue_tg() is called when the
>> last throttled bio is dispatched.
> 
> Ah, okay, so the prev patch was to enable this cleanup. Can you please note
> so in the previous patch and also that this doesn't cause any functional
> changes?
> 

Of course, I'll do that in next iteration.

Thanks,
Kuai
> Thanks.
>
diff mbox series

Patch

diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 473f0b651ef0..29e9f7f6573c 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -561,23 +561,16 @@  static void tg_service_queue_add(struct throtl_grp *tg)
 
 static void throtl_enqueue_tg(struct throtl_grp *tg)
 {
-	if (!(tg->flags & THROTL_TG_PENDING)) {
-		tg_service_queue_add(tg);
-		tg->flags |= THROTL_TG_PENDING;
-		tg->service_queue.parent_sq->nr_pending++;
-	}
+	tg_service_queue_add(tg);
+	tg->service_queue.parent_sq->nr_pending++;
 }
 
 static void throtl_dequeue_tg(struct throtl_grp *tg)
 {
-	if (tg->flags & THROTL_TG_PENDING) {
-		struct throtl_service_queue *parent_sq =
-			tg->service_queue.parent_sq;
+	struct throtl_service_queue *parent_sq = tg->service_queue.parent_sq;
 
-		throtl_rb_erase(&tg->rb_node, parent_sq);
-		--parent_sq->nr_pending;
-		tg->flags &= ~THROTL_TG_PENDING;
-	}
+	throtl_rb_erase(&tg->rb_node, parent_sq);
+	--parent_sq->nr_pending;
 }
 
 /* Call with queue lock held */
@@ -1021,8 +1014,9 @@  static void throtl_add_bio_tg(struct bio *bio, struct throtl_qnode *qn,
 
 	throtl_qnode_add_bio(bio, qn, &sq->queued[rw]);
 
+	if (!sq->nr_queued[READ] && !sq->nr_queued[WRITE])
+		throtl_enqueue_tg(tg);
 	sq->nr_queued[rw]++;
-	throtl_enqueue_tg(tg);
 }
 
 static void tg_update_disptime(struct throtl_grp *tg)
@@ -1377,7 +1371,7 @@  static void tg_conf_updated(struct throtl_grp *tg, bool global)
 	throtl_start_new_slice(tg, READ, false);
 	throtl_start_new_slice(tg, WRITE, false);
 
-	if (tg->flags & THROTL_TG_PENDING) {
+	if (sq->nr_queued[READ] || sq->nr_queued[WRITE]) {
 		tg_update_disptime(tg);
 		throtl_schedule_next_dispatch(sq->parent_sq, true);
 	}
diff --git a/block/blk-throttle.h b/block/blk-throttle.h
index 371d624af845..fba48afbcff3 100644
--- a/block/blk-throttle.h
+++ b/block/blk-throttle.h
@@ -53,10 +53,9 @@  struct throtl_service_queue {
 };
 
 enum tg_state_flags {
-	THROTL_TG_PENDING	= 1 << 0,	/* on parent's pending tree */
-	THROTL_TG_WAS_EMPTY	= 1 << 1,	/* bio_lists[] became non-empty */
-	THROTL_TG_HAS_IOPS_LIMIT = 1 << 2,	/* tg has iops limit */
-	THROTL_TG_CANCELING	= 1 << 3,	/* starts to cancel bio */
+	THROTL_TG_WAS_EMPTY	= 1 << 0,	/* bio_lists[] became non-empty */
+	THROTL_TG_HAS_IOPS_LIMIT = 1 << 1,	/* tg has iops limit */
+	THROTL_TG_CANCELING	= 1 << 2,	/* starts to cancel bio */
 };
 
 enum {