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

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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: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Jens Axboe 2017-02-22 13:19:45 -07:00
parent eed64951f1
commit b86dd815ff
3 changed files with 13 additions and 59 deletions
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44
block/Kconfig.iosched
View File

@ -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

9
block/blk-mq-sched.c
View File

@ -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);

19
block/elevator.c
View File

@ -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);
}
}