| Message ID | 20210111164717.21937-2-jack@suse.cz (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | blk-mq: Improve performance of non-mq IO schedulers with multiple HW queues | expand |
On Mon, Jan 11, 2021 at 05:47:16PM +0100, Jan Kara wrote: > This reverts commit b445547ec1bbd3e7bf4b1c142550942f70527d95. > > Since both mq-deadline and BFQ completely ignore hctx they are passed to > their dispatch function and dispatch whatever request they deem fit > checking whether any request for a particular hctx is queued is just > pointless since we'll very likely get a request from a different hctx > anyway. In the following commit we'll deal with lock contention in these > IO schedulers in presence of multiple HW queues in a different way. > > Signed-off-by: Jan Kara <jack@suse.cz> > --- > block/bfq-iosched.c | 5 ----- > block/blk-mq.c | 1 - > block/mq-deadline.c | 6 ------ > include/linux/blk-mq.h | 4 ---- > 4 files changed, 16 deletions(-) > > diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c > index 9e81d1052091..a99dfaa75a8c 100644 > --- a/block/bfq-iosched.c > +++ b/block/bfq-iosched.c > @@ -4640,9 +4640,6 @@ static bool bfq_has_work(struct blk_mq_hw_ctx *hctx) > { > struct bfq_data *bfqd = hctx->queue->elevator->elevator_data; > > - if (!atomic_read(&hctx->elevator_queued)) > - return false; > - > /* > * Avoiding lock: a race on bfqd->busy_queues should cause at > * most a call to dispatch for nothing > @@ -5557,7 +5554,6 @@ static void bfq_insert_requests(struct blk_mq_hw_ctx *hctx, > rq = list_first_entry(list, struct request, queuelist); > list_del_init(&rq->queuelist); > bfq_insert_request(hctx, rq, at_head); > - atomic_inc(&hctx->elevator_queued); > } > } > > @@ -5925,7 +5921,6 @@ static void bfq_finish_requeue_request(struct request *rq) > > bfq_completed_request(bfqq, bfqd); > bfq_finish_requeue_request_body(bfqq); > - atomic_dec(&rq->mq_hctx->elevator_queued); > > spin_unlock_irqrestore(&bfqd->lock, flags); > } else { > diff --git a/block/blk-mq.c b/block/blk-mq.c > index f285a9123a8b..57f3482b2c26 100644 > --- a/block/blk-mq.c > +++ b/block/blk-mq.c > @@ -2653,7 +2653,6 @@ blk_mq_alloc_hctx(struct request_queue *q, struct blk_mq_tag_set *set, > goto free_hctx; > > atomic_set(&hctx->nr_active, 0); > - atomic_set(&hctx->elevator_queued, 0); > if (node == NUMA_NO_NODE) > node = set->numa_node; > hctx->numa_node = node; > diff --git a/block/mq-deadline.c b/block/mq-deadline.c > index 800ac902809b..b57470e154c8 100644 > --- a/block/mq-deadline.c > +++ b/block/mq-deadline.c > @@ -386,8 +386,6 @@ static struct request *dd_dispatch_request(struct blk_mq_hw_ctx *hctx) > spin_lock(&dd->lock); > rq = __dd_dispatch_request(dd); > spin_unlock(&dd->lock); > - if (rq) > - atomic_dec(&rq->mq_hctx->elevator_queued); > > return rq; > } > @@ -535,7 +533,6 @@ static void dd_insert_requests(struct blk_mq_hw_ctx *hctx, > rq = list_first_entry(list, struct request, queuelist); > list_del_init(&rq->queuelist); > dd_insert_request(hctx, rq, at_head); > - atomic_inc(&hctx->elevator_queued); > } > spin_unlock(&dd->lock); > } > @@ -582,9 +579,6 @@ static bool dd_has_work(struct blk_mq_hw_ctx *hctx) > { > struct deadline_data *dd = hctx->queue->elevator->elevator_data; > > - if (!atomic_read(&hctx->elevator_queued)) > - return false; > - > return !list_empty_careful(&dd->dispatch) || > !list_empty_careful(&dd->fifo_list[0]) || > !list_empty_careful(&dd->fifo_list[1]); > diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h > index d705b174d346..b4b9604bbfd7 100644 > --- a/include/linux/blk-mq.h > +++ b/include/linux/blk-mq.h > @@ -140,10 +140,6 @@ struct blk_mq_hw_ctx { > * shared across request queues. > */ > atomic_t nr_active; > - /** > - * @elevator_queued: Number of queued requests on hctx. > - */ > - atomic_t elevator_queued; > > /** @cpuhp_online: List to store request if CPU is going to die */ > struct hlist_node cpuhp_online; > -- > 2.26.2 > Reviewed-by: Ming Lei <ming.lei@redhat.com>
diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c index 9e81d1052091..a99dfaa75a8c 100644 --- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -4640,9 +4640,6 @@ static bool bfq_has_work(struct blk_mq_hw_ctx *hctx) { struct bfq_data *bfqd = hctx->queue->elevator->elevator_data; - if (!atomic_read(&hctx->elevator_queued)) - return false; - /* * Avoiding lock: a race on bfqd->busy_queues should cause at * most a call to dispatch for nothing @@ -5557,7 +5554,6 @@ static void bfq_insert_requests(struct blk_mq_hw_ctx *hctx, rq = list_first_entry(list, struct request, queuelist); list_del_init(&rq->queuelist); bfq_insert_request(hctx, rq, at_head); - atomic_inc(&hctx->elevator_queued); } } @@ -5925,7 +5921,6 @@ static void bfq_finish_requeue_request(struct request *rq) bfq_completed_request(bfqq, bfqd); bfq_finish_requeue_request_body(bfqq); - atomic_dec(&rq->mq_hctx->elevator_queued); spin_unlock_irqrestore(&bfqd->lock, flags); } else { diff --git a/block/blk-mq.c b/block/blk-mq.c index f285a9123a8b..57f3482b2c26 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -2653,7 +2653,6 @@ blk_mq_alloc_hctx(struct request_queue *q, struct blk_mq_tag_set *set, goto free_hctx; atomic_set(&hctx->nr_active, 0); - atomic_set(&hctx->elevator_queued, 0); if (node == NUMA_NO_NODE) node = set->numa_node; hctx->numa_node = node; diff --git a/block/mq-deadline.c b/block/mq-deadline.c index 800ac902809b..b57470e154c8 100644 --- a/block/mq-deadline.c +++ b/block/mq-deadline.c @@ -386,8 +386,6 @@ static struct request *dd_dispatch_request(struct blk_mq_hw_ctx *hctx) spin_lock(&dd->lock); rq = __dd_dispatch_request(dd); spin_unlock(&dd->lock); - if (rq) - atomic_dec(&rq->mq_hctx->elevator_queued); return rq; } @@ -535,7 +533,6 @@ static void dd_insert_requests(struct blk_mq_hw_ctx *hctx, rq = list_first_entry(list, struct request, queuelist); list_del_init(&rq->queuelist); dd_insert_request(hctx, rq, at_head); - atomic_inc(&hctx->elevator_queued); } spin_unlock(&dd->lock); } @@ -582,9 +579,6 @@ static bool dd_has_work(struct blk_mq_hw_ctx *hctx) { struct deadline_data *dd = hctx->queue->elevator->elevator_data; - if (!atomic_read(&hctx->elevator_queued)) - return false; - return !list_empty_careful(&dd->dispatch) || !list_empty_careful(&dd->fifo_list[0]) || !list_empty_careful(&dd->fifo_list[1]); diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h index d705b174d346..b4b9604bbfd7 100644 --- a/include/linux/blk-mq.h +++ b/include/linux/blk-mq.h @@ -140,10 +140,6 @@ struct blk_mq_hw_ctx { * shared across request queues. */ atomic_t nr_active; - /** - * @elevator_queued: Number of queued requests on hctx. - */ - atomic_t elevator_queued; /** @cpuhp_online: List to store request if CPU is going to die */ struct hlist_node cpuhp_online;
This reverts commit b445547ec1bbd3e7bf4b1c142550942f70527d95. Since both mq-deadline and BFQ completely ignore hctx they are passed to their dispatch function and dispatch whatever request they deem fit checking whether any request for a particular hctx is queued is just pointless since we'll very likely get a request from a different hctx anyway. In the following commit we'll deal with lock contention in these IO schedulers in presence of multiple HW queues in a different way. Signed-off-by: Jan Kara <jack@suse.cz> --- block/bfq-iosched.c | 5 ----- block/blk-mq.c | 1 - block/mq-deadline.c | 6 ------ include/linux/blk-mq.h | 4 ---- 4 files changed, 16 deletions(-)