Re: [PATCH 2/4] blk-mq: introduce blk_mq_get_queue_depth()

Omar Sandoval
2017-05-03T16:55:32Z

On Fri, Apr 28, 2017 at 11:15:37PM +0800, Ming Lei wrote:
> The hardware queue depth can be resized via blk_mq_update_nr_requests(),
> so introduce this helper for retrieving queue's depth easily.

One nit below. If the per-hardware queue tag space situation changes, we
can revisit this and the similar thing in Kyber.

Reviewed-by: Omar Sandoval <osandov@fb.com>

> Signed-off-by: Ming Lei <ming.lei@redhat.com>
> ---
> block/blk-mq.c | 12 ++++++++++++
> block/blk-mq.h | 1 +
> 2 files changed, 13 insertions(+)
>
> diff --git a/block/blk-mq.c b/block/blk-mq.c
> index e530bc54f0d9..04761fb76ab4 100644
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
> @@ -2637,6 +2637,18 @@ void blk_mq_free_tag_set(struct blk_mq_tag_set *set)
> }
> EXPORT_SYMBOL(blk_mq_free_tag_set);
>
> +/*
> + * Queue depth can be changed via blk_mq_update_nr_requests(),
> + * so use this helper to retrieve queue's depth.
> + */
> +int blk_mq_get_queue_depth(struct request_queue *q)
> +{
> + /* All queues have same queue depth */
> + struct blk_mq_tags *tags = q->tag_set->tags[0];

Not sure what's going on with the spacing here. Tab instead of a space?

> + return tags->bitmap_tags.sb.depth;
> +}
> +
> int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr)
> {
> struct blk_mq_tag_set *set = q->tag_set;
> diff --git a/block/blk-mq.h b/block/blk-mq.h
> index 2814a14e529c..8085d5989cf5 100644
> --- a/block/blk-mq.h
> +++ b/block/blk-mq.h
> @@ -166,6 +166,7 @@ void __blk_mq_finish_request(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx,
> void blk_mq_finish_request(struct request *rq);
> struct request *__blk_mq_alloc_request(struct blk_mq_alloc_data *data,
> unsigned int op);
> +int blk_mq_get_queue_depth(struct request_queue *q);
>
> static inline bool blk_mq_hctx_stopped(struct blk_mq_hw_ctx *hctx)
> {
> --
> 2.9.3
>