Commit 4fdb3b9f authored by Federico Gavioli's avatar Federico Gavioli Committed by Jens Axboe
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block, bfq: retrieve independent access ranges from request queue 



This patch implements the code to gather the content of the
independent_access_ranges structure from the request_queue and copy
it into the queue's bfq_data. This copy is done at queue initialization.

We copy the access ranges into the bfq_data to avoid taking the queue
lock each time we access the ranges.

This implementation, however, puts a limit to the maximum independent
ranges supported by the scheduler. Such a limit is equal to the constant
BFQ_MAX_ACTUATORS. This limit was placed to avoid the allocation of
dynamic memory.

Reviewed-by: default avatarDamien Le Moal <damien.lemoal@opensource.wdc.com>
Co-developed-by: default avatarRory Chen <rory.c.chen@seagate.com>
Signed-off-by: default avatarRory Chen <rory.c.chen@seagate.com>
Signed-off-by: default avatarFederico Gavioli <f.gavioli97@gmail.com>
Signed-off-by: default avatarPaolo Valente <paolo.valente@linaro.org>
Link: https://lore.kernel.org/r/20230103145503.71712-7-paolo.valente@linaro.org


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 8b7fd741

block/bfq-iosched.c

+51 −8
Original line number Diff line number Diff line
@@ -1793,10 +1793,25 @@ static bool bfq_bfqq_higher_class_or_weight(struct bfq_queue *bfqq, 
 */

static unsigned int bfq_actuator_index(struct bfq_data *bfqd, struct bio *bio)

{

	/*

	 * Multi-actuator support not complete yet, so always return 0

	 * for the moment (to keep incomplete mechanisms off).

	 */

	unsigned int i;

	sector_t end;



	/* no search needed if one or zero ranges present */

	if (bfqd->num_actuators == 1)

		return 0;



	/* bio_end_sector(bio) gives the sector after the last one */

	end = bio_end_sector(bio) - 1;



	for (i = 0; i < bfqd->num_actuators; i++) {

		if (end >= bfqd->sector[i] &&

		    end < bfqd->sector[i] + bfqd->nr_sectors[i])

			return i;

	}



	WARN_ONCE(true,

		  "bfq_actuator_index: bio sector out of ranges: end=%llu\n",

		  end);

	return 0;

}
@@ -7105,6 +7120,8 @@ static int bfq_init_queue(struct request_queue *q, struct elevator_type *e) 
{

	struct bfq_data *bfqd;

	struct elevator_queue *eq;

	unsigned int i;

	struct blk_independent_access_ranges *ia_ranges = q->disk->ia_ranges;



	eq = elevator_alloc(q, e);

	if (!eq)
@@ -7147,12 +7164,38 @@ static int bfq_init_queue(struct request_queue *q, struct elevator_type *e) 


	bfqd->queue = q;



	bfqd->num_actuators = 1;

	/*

	 * Multi-actuator support not complete yet, unconditionally

	 * set to only one actuator for the moment (to keep incomplete

	 * mechanisms off).

	 * If the disk supports multiple actuators, copy independent

	 * access ranges from the request queue structure.

	 */

	bfqd->num_actuators = 1;

	spin_lock_irq(&q->queue_lock);

	if (ia_ranges) {

		/*

		 * Check if the disk ia_ranges size exceeds the current bfq

		 * actuator limit.

		 */

		if (ia_ranges->nr_ia_ranges > BFQ_MAX_ACTUATORS) {

			pr_crit("nr_ia_ranges higher than act limit: iars=%d, max=%d.\n",

				ia_ranges->nr_ia_ranges, BFQ_MAX_ACTUATORS);

			pr_crit("Falling back to single actuator mode.\n");

		} else {

			bfqd->num_actuators = ia_ranges->nr_ia_ranges;



			for (i = 0; i < bfqd->num_actuators; i++) {

				bfqd->sector[i] = ia_ranges->ia_range[i].sector;

				bfqd->nr_sectors[i] =

					ia_ranges->ia_range[i].nr_sectors;

			}

		}

	}



	/* Otherwise use single-actuator dev info */

	if (bfqd->num_actuators == 1) {

		bfqd->sector[0] = 0;

		bfqd->nr_sectors[0] = get_capacity(q->disk);

	}

	spin_unlock_irq(&q->queue_lock);



	INIT_LIST_HEAD(&bfqd->dispatch);

block/bfq-iosched.h

+7 −1
Original line number Diff line number Diff line
@@ -814,7 +814,13 @@ struct bfq_data { 
	 * case of single-actuator drives.

	 */

	unsigned int num_actuators;



	/*

	 * Disk independent access ranges for each actuator

	 * in this device.

	 */

	sector_t sector[BFQ_MAX_ACTUATORS];

	sector_t nr_sectors[BFQ_MAX_ACTUATORS];

	struct blk_independent_access_range ia_ranges[BFQ_MAX_ACTUATORS];

};



enum bfqq_state_flags {