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Commit b86dd815 authored by Jens Axboe's avatar Jens Axboe
Browse files

block: get rid of blk-mq default scheduler choice Kconfig entries 



The wording in the entries were poor and not understandable
by even deities. Kill the selection for default block scheduler,
and impose a policy with sane defaults.

Architected-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: default avatarOmar Sandoval <osandov@fb.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent eed64951

block/Kconfig.iosched

+0 −44
Original line number Diff line number Diff line
@@ -69,50 +69,6 @@ config MQ_IOSCHED_DEADLINE 
	---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

+0 −9
Original line number Diff line number Diff line
@@ -498,15 +498,6 @@ 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);

block/elevator.c

+13 −6
Original line number Diff line number Diff line
@@ -220,17 +220,24 @@ 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

		/*

		 * For blk-mq devices, we default to using mq-deadline,

		 * if available, for single queue devices. If deadline

		 * isn't available OR we have multiple queues, default

		 * to "none".

		 */

		if (q->mq_ops) {

			if (q->nr_hw_queues == 1)

				e = elevator_get("mq-deadline", false);

			if (!e)

				return 0;

		} else

			e = elevator_get(CONFIG_DEFAULT_IOSCHED, false);



		if (!e) {

			printk(KERN_ERR

				"Default I/O scheduler not found. " \

				"Using noop/none.\n");

				"Using noop.\n");

			e = elevator_get("noop", false);

		}

	}