Commit d3484991 authored by Jens Axboe's avatar Jens Axboe
Browse files

blk-mq-sched: allow setting of default IO scheduler 



Add Kconfig entries to manage what devices get assigned an MQ
scheduler, and add a blk-mq flag for drivers to opt out of scheduling.
The latter is useful for admin type queues that still allocate a blk-mq
queue and tag set, but aren't use for normal IO.

Signed-off-by: default avatarJens Axboe <axboe@fb.com>
Reviewed-by: default avatarBart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: default avatarOmar Sandoval <osandov@fb.com>
parent 945ffb60

block/Kconfig.iosched

+50 −6
Original line number Diff line number Diff line
@@ -32,12 +32,6 @@ config IOSCHED_CFQ 


	  This is the default I/O scheduler.



config MQ_IOSCHED_DEADLINE

	tristate "MQ deadline I/O scheduler"

	default y

	---help---

	  MQ version of the deadline IO scheduler.



config CFQ_GROUP_IOSCHED

	bool "CFQ Group Scheduling support"

	depends on IOSCHED_CFQ && BLK_CGROUP
@@ -69,6 +63,56 @@ config DEFAULT_IOSCHED 
	default "cfq" if DEFAULT_CFQ

	default "noop" if DEFAULT_NOOP



config MQ_IOSCHED_DEADLINE

	tristate "MQ deadline I/O scheduler"

	default y

	---help---

	  MQ version of the deadline IO scheduler.



config MQ_IOSCHED_NONE

	bool

	default y



choice

	prompt "Default single-queue blk-mq I/O scheduler"

	default DEFAULT_SQ_NONE

	help

	  Select the I/O scheduler which will be used by default for blk-mq

	  managed block devices with a single queue.



	config DEFAULT_SQ_DEADLINE

		bool "MQ Deadline" if MQ_IOSCHED_DEADLINE=y



	config DEFAULT_SQ_NONE

		bool "None"



endchoice



config DEFAULT_SQ_IOSCHED

	string

	default "mq-deadline" if DEFAULT_SQ_DEADLINE

	default "none" if DEFAULT_SQ_NONE



choice

	prompt "Default multi-queue blk-mq I/O scheduler"

	default DEFAULT_MQ_NONE

	help

	  Select the I/O scheduler which will be used by default for blk-mq

	  managed block devices with multiple queues.



	config DEFAULT_MQ_DEADLINE

		bool "MQ Deadline" if MQ_IOSCHED_DEADLINE=y



	config DEFAULT_MQ_NONE

		bool "None"



endchoice



config DEFAULT_MQ_IOSCHED

	string

	default "mq-deadline" if DEFAULT_MQ_DEADLINE

	default "none" if DEFAULT_MQ_NONE



endmenu



endif

block/blk-mq-sched.c

+20 −0
Original line number Diff line number Diff line
@@ -366,3 +366,23 @@ void blk_mq_sched_teardown(struct request_queue *q) 
	queue_for_each_hw_ctx(q, hctx, i)

		blk_mq_sched_free_tags(set, hctx, i);

}



int blk_mq_sched_init(struct request_queue *q)

{

	int ret;



#if defined(CONFIG_DEFAULT_SQ_NONE)

	if (q->nr_hw_queues == 1)

		return 0;

#endif

#if defined(CONFIG_DEFAULT_MQ_NONE)

	if (q->nr_hw_queues > 1)

		return 0;

#endif



	mutex_lock(&q->sysfs_lock);

	ret = elevator_init(q, NULL);

	mutex_unlock(&q->sysfs_lock);



	return ret;

}

block/blk-mq-sched.h

+2 −0
Original line number Diff line number Diff line
@@ -28,6 +28,8 @@ void blk_mq_sched_move_to_dispatch(struct blk_mq_hw_ctx *hctx, 
int blk_mq_sched_setup(struct request_queue *q);

void blk_mq_sched_teardown(struct request_queue *q);



int blk_mq_sched_init(struct request_queue *q);



static inline bool

blk_mq_sched_bio_merge(struct request_queue *q, struct bio *bio)

{

block/blk-mq.c

+8 −0
Original line number Diff line number Diff line
@@ -2285,6 +2285,14 @@ struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set, 
	mutex_unlock(&all_q_mutex);

	put_online_cpus();



	if (!(set->flags & BLK_MQ_F_NO_SCHED)) {

		int ret;



		ret = blk_mq_sched_init(q);

		if (ret)

			return ERR_PTR(ret);

	}



	return q;



err_hctxs:

block/elevator.c

+7 −1
Original line number Diff line number Diff line
@@ -219,7 +219,13 @@ int elevator_init(struct request_queue *q, char *name) 
	}



	if (!e) {

		if (q->mq_ops && q->nr_hw_queues == 1)

			e = elevator_get(CONFIG_DEFAULT_SQ_IOSCHED, false);

		else if (q->mq_ops)

			e = elevator_get(CONFIG_DEFAULT_MQ_IOSCHED, false);

		else

			e = elevator_get(CONFIG_DEFAULT_IOSCHED, false);



		if (!e) {

			printk(KERN_ERR

				"Default I/O scheduler not found. " \

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