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block: Make writeback throttling defaults consistent for SQ devices 

When CFQ is used as an elevator, it disables writeback throttling
because they don't play well together. Later when a different elevator
is chosen for the device, writeback throttling doesn't get enabled
again as it should. Make sure CFQ enables writeback throttling (if it
should be enabled by default) when we switch from it to another IO
scheduler.

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Jan Kara 2017-04-19 11:33:27 +02:00 committed by Jens Axboe
parent ea25da4808
commit 8330cdb0fe
4 changed files with 27 additions and 18 deletions
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19
block/blk-sysfs.c
View File

@ -844,23 +844,6 @@ struct kobj_type blk_queue_ktype = {
.release = blk_release_queue,
};
static void blk_wb_init(struct request_queue *q)
{
#ifndef CONFIG_BLK_WBT_MQ
if (q->mq_ops)
return;
#endif
#ifndef CONFIG_BLK_WBT_SQ
if (q->request_fn)
return;
#endif
/*
* If this fails, we don't get throttling
*/
wbt_init(q);
}
int blk_register_queue(struct gendisk *disk)
{
int ret;
@ -908,7 +891,7 @@ int blk_register_queue(struct gendisk *disk)
kobject_uevent(&q->kobj, KOBJ_ADD);
blk_wb_init(q);
wbt_enable_default(q);
blk_throtl_register_queue(q);

19
block/blk-wbt.c
View File

@ -665,6 +665,25 @@ void wbt_disable_default(struct request_queue *q)
}
EXPORT_SYMBOL_GPL(wbt_disable_default);
/*
* Enable wbt if defaults are configured that way
*/
void wbt_enable_default(struct request_queue *q)
{
/* Throttling already enabled? */
if (q->rq_wb)
return;
/* Queue not registered? Maybe shutting down... */
if (!test_bit(QUEUE_FLAG_REGISTERED, &q->queue_flags))
return;
if ((q->mq_ops && IS_ENABLED(CONFIG_BLK_WBT_MQ)) ||
(q->request_fn && IS_ENABLED(CONFIG_BLK_WBT_SQ)))
wbt_init(q);
}
EXPORT_SYMBOL_GPL(wbt_enable_default);
u64 wbt_default_latency_nsec(struct request_queue *q)
{
/*

4
block/blk-wbt.h
View File

@ -117,6 +117,7 @@ void wbt_update_limits(struct rq_wb *);
void wbt_requeue(struct rq_wb *, struct blk_issue_stat *);
void wbt_issue(struct rq_wb *, struct blk_issue_stat *);
void wbt_disable_default(struct request_queue *);
void wbt_enable_default(struct request_queue *);
void wbt_set_queue_depth(struct rq_wb *, unsigned int);
void wbt_set_write_cache(struct rq_wb *, bool);
@ -155,6 +156,9 @@ static inline void wbt_issue(struct rq_wb *rwb, struct blk_issue_stat *stat)
static inline void wbt_disable_default(struct request_queue *q)
{
}
static inline void wbt_enable_default(struct request_queue *q)
{
}
static inline void wbt_set_queue_depth(struct rq_wb *rwb, unsigned int depth)
{
}

3
block/elevator.c
View File

@ -41,6 +41,7 @@
#include "blk.h"
#include "blk-mq-sched.h"
#include "blk-wbt.h"
static DEFINE_SPINLOCK(elv_list_lock);
static LIST_HEAD(elv_list);
@ -877,6 +878,8 @@ void elv_unregister_queue(struct request_queue *q)
kobject_uevent(&e->kobj, KOBJ_REMOVE);
kobject_del(&e->kobj);
e->registered = 0;
/* Re-enable throttling in case elevator disabled it */
wbt_enable_default(q);
}
}
EXPORT_SYMBOL(elv_unregister_queue);