Re: [PATCH] blk-mq: count the hctx as active before allocate tag

[Ming Lei]

On Wed, Aug 8, 2018 at 4:22 PM, Jianchao Wang
<jianchao.w.wang@xxxxxxxxxx> wrote:
> Currently, we count the hctx as active after allocate tag
> successfully. The other shared-tags users could exhaust the tags
> and starve a non-active and waiting-tag hctx. Count the hctx as
> active before try to allocate tag to fix this.

This patch looks fine.

>
> Signed-off-by: Jianchao Wang <jianchao.w.wang@xxxxxxxxxx>
> ---
>  block/blk-mq.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/block/blk-mq.c b/block/blk-mq.c
> index ae44e85..acd40eb 100644
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
> @@ -369,6 +369,8 @@ static struct request *blk_mq_get_request(struct request_queue *q,
>                         e->type->ops.mq.limit_depth(op, data);
>         }
>
> +       blk_mq_tag_busy(data.hctx);
> +

blk_mq_tag_busy is only required for driver tag.

Thanks,
Ming Lei