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authorJens Axboe <axboe@fb.com>2017-01-26 12:40:07 -0700
committerJens Axboe <axboe@fb.com>2017-01-27 08:20:35 -0700
commitc13660a08c8b3bb49def4374bfd414aaaa564662 (patch)
treec7a61741aba75e320838865f176092c07af37f95 /include/linux/elevator.h
parent50e1dab86aa2c10cbca2f754aae9542169403141 (diff)
blk-mq-sched: change ->dispatch_requests() to ->dispatch_request()
When we invoke dispatch_requests(), the scheduler empties everything into the passed in list. This isn't always a good thing, since it means that we remove items that we could have potentially merged with. Change the function to dispatch single requests at the time. If we do that, we can backoff exactly at the point where the device can't consume more IO, and leave the rest with the scheduler for better merging and future dispatch decision making. Signed-off-by: Jens Axboe <axboe@fb.com> Reviewed-by: Omar Sandoval <osandov@fb.com> Tested-by: Hannes Reinecke <hare@suse.com>
Diffstat (limited to 'include/linux/elevator.h')
-rw-r--r--include/linux/elevator.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/elevator.h b/include/linux/elevator.h
index ecb96fd67c6d..b5825c4f06f7 100644
--- a/include/linux/elevator.h
+++ b/include/linux/elevator.h
@@ -92,7 +92,7 @@ struct elevator_mq_ops {
struct request *(*get_request)(struct request_queue *, unsigned int, struct blk_mq_alloc_data *);
void (*put_request)(struct request *);
void (*insert_requests)(struct blk_mq_hw_ctx *, struct list_head *, bool);
- void (*dispatch_requests)(struct blk_mq_hw_ctx *, struct list_head *);
+ struct request *(*dispatch_request)(struct blk_mq_hw_ctx *);
bool (*has_work)(struct blk_mq_hw_ctx *);
void (*completed_request)(struct blk_mq_hw_ctx *, struct request *);
void (*started_request)(struct request *);