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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 /block/mq-deadline.c
parent50e1dab86aa2c10cbca2f754aae9542169403141 (diff)
downloadlinux-0-day-c13660a08c8b3bb49def4374bfd414aaaa564662.tar.gz
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 'block/mq-deadline.c')
-rw-r--r--block/mq-deadline.c10
1 files changed, 6 insertions, 4 deletions
diff --git a/block/mq-deadline.c b/block/mq-deadline.c
index a01986d..d93ec71 100644
--- a/block/mq-deadline.c
+++ b/block/mq-deadline.c
@@ -287,14 +287,16 @@ done:
return rq;
}
-static void dd_dispatch_requests(struct blk_mq_hw_ctx *hctx,
- struct list_head *rq_list)
+static struct request *dd_dispatch_request(struct blk_mq_hw_ctx *hctx)
{
struct deadline_data *dd = hctx->queue->elevator->elevator_data;
+ struct request *rq;
spin_lock(&dd->lock);
- blk_mq_sched_move_to_dispatch(hctx, rq_list, __dd_dispatch_request);
+ rq = __dd_dispatch_request(hctx);
spin_unlock(&dd->lock);
+
+ return rq;
}
static void dd_exit_queue(struct elevator_queue *e)
@@ -517,7 +519,7 @@ static struct elv_fs_entry deadline_attrs[] = {
static struct elevator_type mq_deadline = {
.ops.mq = {
.insert_requests = dd_insert_requests,
- .dispatch_requests = dd_dispatch_requests,
+ .dispatch_request = dd_dispatch_request,
.next_request = elv_rb_latter_request,
.former_request = elv_rb_former_request,
.bio_merge = dd_bio_merge,