On 12/8/22 19:43, Paolo Valente wrote:
> From: Federico Gavioli <f.gavioli97@xxxxxxxxx>
>
> 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.
>
> Co-developed-by: Rory Chen <rory.c.chen@xxxxxxxxxxx>
> Signed-off-by: Rory Chen <rory.c.chen@xxxxxxxxxxx>
> Signed-off-by: Federico Gavioli <f.gavioli97@xxxxxxxxx>
> Signed-off-by: Paolo Valente <paolo.valente@xxxxxxxxxx>
> ---
> block/bfq-iosched.c | 60 +++++++++++++++++++++++++++++++++++++++------
> block/bfq-iosched.h | 8 +++++-
> 2 files changed, 59 insertions(+), 9 deletions(-)
>
> diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
> index dcecba3c6e23..957ce61faaf2 100644
> --- a/block/bfq-iosched.c
> +++ b/block/bfq-iosched.c
> @@ -1839,10 +1839,25 @@ 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;
> }
>
> @@ -7160,6 +7175,8 @@ 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)
> @@ -7202,12 +7219,39 @@ 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] =
> + bdev_nr_sectors(dev_to_bdev(disk_to_dev(q->disk)));
get_capacity(q->disk) would be simpler.
> + }
> + spin_unlock_irq(&q->queue_lock);
>
> INIT_LIST_HEAD(&bfqd->dispatch);
>
> diff --git a/block/bfq-iosched.h b/block/bfq-iosched.h
> index 1450990dba32..953980de6b4b 100644
> --- a/block/bfq-iosched.h
> +++ b/block/bfq-iosched.h
> @@ -810,7 +810,13 @@ 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 {
With the nit above fixed,
Reviewed-by: Damien Le Moal <damien.lemoal@xxxxxxxxxxxxxxxxxx>
--
Damien Le Moal
Western Digital Research
