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Date: Wed, 5 Oct 2022 07:53:38 +0900
From: Damien Le Moal <damien.lemoal@...nsource.wdc.com>
To: Paolo Valente <paolo.valente@...aro.org>,
Jens Axboe <axboe@...nel.dk>
Cc: linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
jack@...e.cz, andrea.righi@...onical.com, glen.valante@...aro.org,
arie.vanderhoeven@...gate.com, rory.c.chen@...gate.com,
Federico Gavioli <f.gavioli97@...il.com>
Subject: Re: [PATCH V3 6/8] block, bfq: retrieve independent access ranges
from request queue
On 10/4/22 18:40, Paolo Valente wrote:
> From: Federico Gavioli <f.gavioli97@...il.com>
>
> 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: Damien Le Moal <Damien.LeMoal@....com>
I merely commented on a point you raised. That was not a patch review. So
please do not add my RB tag without me sending it. And my preferred email
address is damien.lemoal@...nsource.wdc.com.
Also, please send the whole series to have context for each patch.
> Co-developed-by: Rory Chen <rory.c.chen@...gate.com>
> Signed-off-by: Federico Gavioli <f.gavioli97@...il.com>
> Signed-off-by: Paolo Valente <paolo.valente@...aro.org>
> Signed-off-by: Rory Chen <rory.c.chen@...gate.com>
> ---
> block/bfq-cgroup.c | 2 +-
> block/bfq-iosched.c | 59 ++++++++++++++++++++++++++++++++++++++-------
> block/bfq-iosched.h | 12 +++++++++
> 3 files changed, 63 insertions(+), 10 deletions(-)
>
> diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c
> index 3b4a0363d617..080d9160217b 100644
> --- a/block/bfq-cgroup.c
> +++ b/block/bfq-cgroup.c
> @@ -764,7 +764,7 @@ static void *__bfq_bic_change_cgroup(struct bfq_data *bfqd,
> struct bfq_entity *entity;
> unsigned int act_idx;
>
> - for (act_idx = 0; act_idx < BFQ_MAX_ACTUATORS; act_idx++) {
> + for (act_idx = 0; act_idx < bfqd->num_ia_ranges; act_idx++) {
> struct bfq_queue *async_bfqq = bic_to_bfqq(bic, 0, act_idx);
> struct bfq_queue *sync_bfqq = bic_to_bfqq(bic, 1, act_idx);
>
> diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
> index d8a15427a96d..9203b4604da8 100644
> --- a/block/bfq-iosched.c
> +++ b/block/bfq-iosched.c
> @@ -689,7 +689,7 @@ static void bfq_limit_depth(blk_opf_t opf, struct blk_mq_alloc_data *data)
> limit = (limit * depth) >> bfqd->full_depth_shift;
> }
>
> - for (act_idx = 0; act_idx < BFQ_MAX_ACTUATORS; act_idx++) {
> + for (act_idx = 0; act_idx < bfqd->num_ia_ranges; act_idx++) {
> struct bfq_queue *bfqq =
> bic ? bic_to_bfqq(bic, op_is_sync(opf), act_idx) : NULL;
>
> @@ -1829,10 +1829,25 @@ static bool bfq_bfqq_higher_class_or_weight(struct bfq_queue *bfqq,
> /* get the index of the actuator that will serve bio */
> 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.
> - */
> + struct blk_independent_access_range *iar;
> + unsigned int i;
> + sector_t end;
> +
> + if (bfqd->num_ia_ranges == 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_ia_ranges; i++) {
> + iar = &(bfqd->ia_ranges[i]);
> + if (end >= iar->sector && end < iar->sector + iar->nr_sectors)
> + return i;
> + }
> +
> + WARN_ONCE(true,
> + "bfq_actuator_index: bio sector out of ranges: end=%llu\n",
> + end);
> return 0;
> }
>
> @@ -2477,7 +2492,6 @@ static void bfq_remove_request(struct request_queue *q,
>
> if (rq->cmd_flags & REQ_META)
> bfqq->meta_pending--;
> -
> }
>
> static bool bfq_bio_merge(struct request_queue *q, struct bio *bio,
> @@ -2673,7 +2687,7 @@ void bfq_end_wr_async_queues(struct bfq_data *bfqd,
> {
> int i, j, k;
>
> - for (k = 0; k < BFQ_MAX_ACTUATORS; k++) {
> + for (k = 0; k < bfqd->num_ia_ranges; k++) {
> for (i = 0; i < 2; i++)
> for (j = 0; j < IOPRIO_NR_LEVELS; j++)
> if (bfqg->async_bfqq[i][j][k])
> @@ -5432,7 +5446,7 @@ static void bfq_exit_icq(struct io_cq *icq)
> if (bfqd)
> spin_lock_irqsave(&bfqd->lock, flags);
>
> - for (act_idx = 0; act_idx < BFQ_MAX_ACTUATORS; act_idx++) {
> + for (act_idx = 0; act_idx < bfqd->num_ia_ranges; act_idx++) {
> if (bic->stable_merge_bfqq[act_idx])
> bfq_put_stable_ref(bic->stable_merge_bfqq[act_idx]);
>
> @@ -7003,7 +7017,7 @@ void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg)
> {
> int i, j, k;
>
> - for (k = 0; k < BFQ_MAX_ACTUATORS; k++) {
> + for (k = 0; k < bfqd->num_ia_ranges; k++) {
> for (i = 0; i < 2; i++)
> for (j = 0; j < IOPRIO_NR_LEVELS; j++)
> __bfq_put_async_bfqq(bfqd, &bfqg->async_bfqq[i][j][k]);
> @@ -7120,6 +7134,8 @@ 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)
> @@ -7162,6 +7178,31 @@ static int bfq_init_queue(struct request_queue *q, struct elevator_type *e)
>
> bfqd->queue = q;
>
> + /*
> + * If the disk supports multiple actuators, we copy the independent
> + * access ranges from the request queue structure.
> + */
> + 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");
> + bfqd->num_ia_ranges = 1;
Setting this to one, one would expect bfqd->ia_ranges[0] to contain valid
information. So shouldn't you set it to sector 0 and nr_sector == capacity ?
> + } else {
> + bfqd->num_ia_ranges = ia_ranges->nr_ia_ranges;
> +
> + for (i = 0; i < bfqd->num_ia_ranges; i++)
> + bfqd->ia_ranges[i] = ia_ranges->ia_range[i];
> + }
> + } else
> + bfqd->num_ia_ranges = 1;
Missing the curly brackets after else.
> + spin_unlock_irq(&q->queue_lock);
> +
> INIT_LIST_HEAD(&bfqd->dispatch);
>
> hrtimer_init(&bfqd->idle_slice_timer, CLOCK_MONOTONIC,
> diff --git a/block/bfq-iosched.h b/block/bfq-iosched.h
> index f9ccf468edc2..34f7603bb62f 100644
> --- a/block/bfq-iosched.h
> +++ b/block/bfq-iosched.h
> @@ -796,6 +796,18 @@ struct bfq_data {
> */
> unsigned int word_depths[2][2];
> unsigned int full_depth_shift;
> +
> + /*
> + * Number of independent access ranges. This is equal to 1 in
> + * case of single actuator drives.
> + */
> + unsigned int num_ia_ranges;
> +
> + /*
> + * Disk independent access ranges for each actuator
> + * in this device.
> + */
> + struct blk_independent_access_range ia_ranges[BFQ_MAX_ACTUATORS];
> };
>
> enum bfqq_state_flags {
--
Damien Le Moal
Western Digital Research
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