[RFC PATCH 4/8] bfq: expire bfqq if a higher priority class is waiting
From: brookxu <hidden>
Date: 2021-03-08 12:01:22
Also in:
cgroups, lkml
Subsystem:
bfq i/o scheduler, block layer, the rest · Maintainers:
Yu Kuai, Jens Axboe, Linus Torvalds
From: Chunguang Xu <redacted> From: Chunguang Xu <redacted> Expire bfqq If a higher priority class is waiting to be served, we can further guarantee the delay of the higher priority class. Signed-off-by: Chunguang Xu <redacted> --- block/bfq-iosched.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+)
diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index b639cdbb4192..223affaa7c92 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c@@ -4677,7 +4677,10 @@ static struct request *bfq_dispatch_rq_from_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq) { struct request *rq = bfqq->next_rq; + struct bfq_sched_data *sd = bfqq->entity.sched_data; + struct bfq_service_tree *st = sd->service_tree; unsigned long service_to_charge; + int idx; service_to_charge = bfq_serv_to_charge(rq, bfqq);
@@ -4714,6 +4717,17 @@ static struct request *bfq_dispatch_rq_from_bfqq(struct bfq_data *bfqd, if (!(bfq_tot_busy_queues(bfqd) > 1 && bfq_class_idle(bfqq))) goto return_rq; + /* + * Expire bfqq, if other queues belong to higher priority + * class are waiting for service. + */ + for (idx = bfqq->ioprio_class - 2; idx >= 0; idx--) { + if (!RB_EMPTY_ROOT(&(st + idx)->active)) + break; + } + if (idx < 0) + goto return_rq; + bfq_bfqq_expire(bfqd, bfqq, false, BFQQE_BUDGET_EXHAUSTED); return_rq:
--
2.30.0