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>
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);
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;