[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <91799590-15cd-437d-900f-8bc372f7298b@linux.ibm.com>
Date: Thu, 2 Oct 2025 20:40:46 +0530
From: Nilay Shroff <nilay@...ux.ibm.com>
To: Yu Kuai <yukuai1@...weicloud.com>, axboe@...nel.dk, bvanassche@....org,
ming.lei@...hat.com
Cc: linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
yukuai3@...wei.com, yi.zhang@...wei.com, yangerkun@...wei.com,
johnny.chenyi@...wei.com
Subject: Re: [PATCH 3/7] blk-mq: add a new queue sysfs attribute async_depth
On 9/30/25 12:41 PM, Yu Kuai wrote:
> From: Yu Kuai <yukuai3@...wei.com>
>
> Add a new field async_depth to request_queue and related APIs, this is
> currently not used, following patches will convert elevators to use
> this instead of internal async_depth.
>
> Signed-off-by: Yu Kuai <yukuai3@...wei.com>
> ---
> block/blk-core.c | 1 +
> block/blk-mq.c | 4 ++++
> block/blk-sysfs.c | 47 ++++++++++++++++++++++++++++++++++++++++++
> block/elevator.c | 1 +
> include/linux/blkdev.h | 1 +
> 5 files changed, 54 insertions(+)
>
> diff --git a/block/blk-core.c b/block/blk-core.c
> index dd39ff651095..76df70cfc103 100644
> --- a/block/blk-core.c
> +++ b/block/blk-core.c
> @@ -463,6 +463,7 @@ struct request_queue *blk_alloc_queue(struct queue_limits *lim, int node_id)
> fs_reclaim_release(GFP_KERNEL);
>
> q->nr_requests = BLKDEV_DEFAULT_RQ;
> + q->async_depth = BLKDEV_DEFAULT_RQ;
>
> return q;
>
> diff --git a/block/blk-mq.c b/block/blk-mq.c
> index 09f579414161..260e54fa48f0 100644
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
> @@ -529,6 +529,8 @@ static struct request *__blk_mq_alloc_requests(struct blk_mq_alloc_data *data)
> data->rq_flags |= RQF_USE_SCHED;
> if (ops->limit_depth)
> ops->limit_depth(data->cmd_flags, data);
> + else if (!blk_mq_sched_sync_request(data->cmd_flags))
> + data->shallow_depth = q->async_depth;
> }
In the subsequent patches, I saw that ->limit_depth is still used for the
BFQ scheduler. Given that, it seems more consistent to also retain ->limit_depth
for the mq-deadline and Kyber schedulers, and set data->shallow_depth within their
respective ->limit_depth methods. If we take this approach, the additional
blk_mq_sched_sync_request() check above becomes unnecessary.
So IMO:
- Keep ->limit_depth for all schedulers (bfq, mq-deadline, kyber).
- Remove the extra blk_mq_sched_sync_request() check from the core code.
Thanks,
--Nilay
Powered by blists - more mailing lists