[PATCH v8 2/9] block/mq-deadline: Only use zone locking if necessary
From: Bart Van Assche <bvanassche@acm.org>
Date: 2023-08-11 21:36:17
Also in:
linux-scsi
Subsystem:
block layer, the rest · Maintainers:
Jens Axboe, Linus Torvalds
Measurements have shown that limiting the queue depth to one per zone for zoned writes has a significant negative performance impact on zoned UFS devices. Hence this patch that disables zone locking by the mq-deadline scheduler if the storage controller preserves the command order. This patch is based on the following assumptions: - It happens infrequently that zoned write requests are reordered by the block layer. - The I/O priority of all write requests is the same per zone. - Either no I/O scheduler is used or an I/O scheduler is used that serializes write requests per zone. Cc: Damien Le Moal <dlemoal@kernel.org> Cc: Christoph Hellwig <hch@lst.de> Cc: Ming Lei <redacted> Signed-off-by: Bart Van Assche <bvanassche@acm.org> --- block/mq-deadline.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-)
diff --git a/block/mq-deadline.c b/block/mq-deadline.c
index f958e79277b8..5c2fc4003bc0 100644
--- a/block/mq-deadline.c
+++ b/block/mq-deadline.c@@ -353,7 +353,7 @@ deadline_fifo_request(struct deadline_data *dd, struct dd_per_prio *per_prio, return NULL; rq = rq_entry_fifo(per_prio->fifo_list[data_dir].next); - if (data_dir == DD_READ || !blk_queue_is_zoned(rq->q)) + if (data_dir == DD_READ || !rq->q->limits.use_zone_write_lock) return rq; /*
@@ -398,7 +398,7 @@ deadline_next_request(struct deadline_data *dd, struct dd_per_prio *per_prio, if (!rq) return NULL; - if (data_dir == DD_READ || !blk_queue_is_zoned(rq->q)) + if (data_dir == DD_READ || !rq->q->limits.use_zone_write_lock) return rq; /*
@@ -526,8 +526,9 @@ static struct request *__dd_dispatch_request(struct deadline_data *dd, } /* - * For a zoned block device, if we only have writes queued and none of - * them can be dispatched, rq will be NULL. + * For a zoned block device that requires write serialization, if we + * only have writes queued and none of them can be dispatched, rq will + * be NULL. */ if (!rq) return NULL;
@@ -552,7 +553,8 @@ static struct request *__dd_dispatch_request(struct deadline_data *dd, /* * If the request needs its target zone locked, do it. */ - blk_req_zone_write_lock(rq); + if (rq->q->limits.use_zone_write_lock) + blk_req_zone_write_lock(rq); rq->rq_flags |= RQF_STARTED; return rq; }
@@ -934,7 +936,7 @@ static void dd_finish_request(struct request *rq) atomic_inc(&per_prio->stats.completed); - if (blk_queue_is_zoned(q)) { + if (rq->q->limits.use_zone_write_lock) { unsigned long flags; spin_lock_irqsave(&dd->zone_lock, flags);