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| author | Baolin Wang <baolin.wang@linux.alibaba.com> | 2020-10-08 11:52:27 +0800 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2020-10-08 08:01:38 -0600 |
| commit | 2397611ac802c4f8028b6b2e585b9857d2f8138b (patch) | |
| tree | 860f4f541bbfaa27643a098bdc190422ea4814cb /block | |
| parent | b7b609de5a0835b2ca10c71df5d9570008eb1084 (diff) | |
| download | lwn-2397611ac802c4f8028b6b2e585b9857d2f8138b.tar.gz lwn-2397611ac802c4f8028b6b2e585b9857d2f8138b.zip | |
blk-throttle: Move service tree validation out of the throtl_rb_first()
The throtl_schedule_next_dispatch() will validate if the service queue
is empty before calling update_min_dispatch_time(), and the
update_min_dispatch_time() will call throtl_rb_first(), which will
validate service queue again.
Thus we can move the service queue validation out of the
throtl_rb_first() to remove the redundant validation in the fast path.
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block')
| -rw-r--r-- | block/blk-throttle.c | 9 |
1 files changed, 5 insertions, 4 deletions
diff --git a/block/blk-throttle.c b/block/blk-throttle.c index f1bcb5c320e8..38aed8baacf4 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -638,9 +638,6 @@ static struct throtl_grp * throtl_rb_first(struct throtl_service_queue *parent_sq) { struct rb_node *n; - /* Service tree is empty */ - if (!parent_sq->nr_pending) - return NULL; n = rb_first_cached(&parent_sq->pending_tree); WARN_ON_ONCE(!n); @@ -1224,9 +1221,13 @@ static int throtl_select_dispatch(struct throtl_service_queue *parent_sq) unsigned int nr_disp = 0; while (1) { - struct throtl_grp *tg = throtl_rb_first(parent_sq); + struct throtl_grp *tg; struct throtl_service_queue *sq; + if (!parent_sq->nr_pending) + break; + + tg = throtl_rb_first(parent_sq); if (!tg) break; |