Commit d88cbbb3 authored by Christophe JAILLET's avatar Christophe JAILLET Committed by Jens Axboe
Browse files

blk-mq: Reorder fields in 'struct blk_mq_tag_set' 



Group some variables based on their sizes to reduce hole and avoid padding.
On x86_64, this shrinks the size of 'struct blk_mq_tag_set'
from 304 to 296 bytes.

Signed-off-by: default avatarChristophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/6f249f9b02a3490283ef0278096556de41aa0cf0.1676626130.git.christophe.jaillet@wanadoo.fr


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent e5cfefa9

include/linux/blk-mq.h

+2 −2
Original line number Diff line number Diff line
@@ -473,6 +473,7 @@ enum hctx_type { 


/**

 * struct blk_mq_tag_set - tag set that can be shared between request queues

 * @ops:	   Pointers to functions that implement block driver behavior.

 * @map:	   One or more ctx -> hctx mappings. One map exists for each

 *		   hardware queue type (enum hctx_type) that the driver wishes

 *		   to support. There are no restrictions on maps being of the
@@ -480,7 +481,6 @@ enum hctx_type { 
 *		   types.

 * @nr_maps:	   Number of elements in the @map array. A number in the range

 *		   [1, HCTX_MAX_TYPES].

 * @ops:	   Pointers to functions that implement block driver behavior.

 * @nr_hw_queues:  Number of hardware queues supported by the block driver that

 *		   owns this data structure.

 * @queue_depth:   Number of tags per hardware queue, reserved tags included.
@@ -505,9 +505,9 @@ enum hctx_type { 
 *		   (BLK_MQ_F_BLOCKING).

 */

struct blk_mq_tag_set {

	const struct blk_mq_ops	*ops;

	struct blk_mq_queue_map	map[HCTX_MAX_TYPES];

	unsigned int		nr_maps;

	const struct blk_mq_ops	*ops;

	unsigned int		nr_hw_queues;

	unsigned int		queue_depth;

	unsigned int		reserved_tags;