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Commit d278d4a8 authored by Jens Axboe's avatar Jens Axboe
Browse files

block: add code to track actual device queue depth 



For blk-mq, ->nr_requests does track queue depth, at least at init
time. But for the older queue paths, it's simply a soft setting.
On top of that, it's generally larger than the hardware setting
on purpose, to allow backup of requests for merging.

Fill a hole in struct request with a 'queue_depth' member, that
drivers can call to more closely inform the block layer of the
real queue depth.

Signed-off-by: default avatarJens Axboe <axboe@fb.com>
Reviewed-by: default avatarJan Kara <jack@suse.cz>
parent 600271d9

block/blk-settings.c

+12 −0
Original line number Diff line number Diff line
@@ -836,6 +836,18 @@ void blk_queue_flush_queueable(struct request_queue *q, bool queueable) 
}

EXPORT_SYMBOL_GPL(blk_queue_flush_queueable);



/**

 * blk_set_queue_depth - tell the block layer about the device queue depth

 * @q:		the request queue for the device

 * @depth:		queue depth

 *

 */

void blk_set_queue_depth(struct request_queue *q, unsigned int depth)

{

	q->queue_depth = depth;

}

EXPORT_SYMBOL(blk_set_queue_depth);



/**

 * blk_queue_write_cache - configure queue's write cache

 * @q:		the request queue for the device

drivers/scsi/scsi.c

+3 −0
Original line number Diff line number Diff line
@@ -621,6 +621,9 @@ int scsi_change_queue_depth(struct scsi_device *sdev, int depth) 
		wmb();

	}



	if (sdev->request_queue)

		blk_set_queue_depth(sdev->request_queue, depth);



	return sdev->queue_depth;

}

EXPORT_SYMBOL(scsi_change_queue_depth);

include/linux/blkdev.h

+11 −0
Original line number Diff line number Diff line
@@ -405,6 +405,8 @@ struct request_queue { 
	struct blk_mq_ctx __percpu	*queue_ctx;

	unsigned int		nr_queues;



	unsigned int		queue_depth;



	/* hw dispatch queues */

	struct blk_mq_hw_ctx	**queue_hw_ctx;

	unsigned int		nr_hw_queues;
@@ -777,6 +779,14 @@ static inline bool blk_write_same_mergeable(struct bio *a, struct bio *b) 
	return false;

}



static inline unsigned int blk_queue_depth(struct request_queue *q)

{

	if (q->queue_depth)

		return q->queue_depth;



	return q->nr_requests;

}



/*

 * q->prep_rq_fn return values

 */
@@ -1094,6 +1104,7 @@ extern void blk_limits_io_min(struct queue_limits *limits, unsigned int min); 
extern void blk_queue_io_min(struct request_queue *q, unsigned int min);

extern void blk_limits_io_opt(struct queue_limits *limits, unsigned int opt);

extern void blk_queue_io_opt(struct request_queue *q, unsigned int opt);

extern void blk_set_queue_depth(struct request_queue *q, unsigned int depth);

extern void blk_set_default_limits(struct queue_limits *lim);

extern void blk_set_stacking_limits(struct queue_limits *lim);

extern int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,