linux-kernel - Re: [PATCH] mmc: queue: replace immediate with hsq->depth

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Date:   Tue, 8 Aug 2023 11:27:40 +0200
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Wenchao Chen <wenchao.chen@...soc.com>
Cc:     linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org,
        wenchao.chen666@...il.com, zhenxiong.lai@...soc.com,
        chunyan.zhang@...soc.com, yuelin.tang@...soc.com
Subject: Re: [PATCH] mmc: queue: replace immediate with hsq->depth

On Thu, 3 Aug 2023 at 07:46, Wenchao Chen <wenchao.chen@...soc.com> wrote:
>
> Hsq is similar to cqe, using hsq->depth to represent
> the maximum processing capacity of hsq. We can adjust
> hsq->depth according to the actual situation.

Sorry, but I don't quite follow here.

Are you planning to update the host->hsq_depth dynamically from somewhere?

Kind regards
Uffe

>
> Signed-off-by: Wenchao Chen <wenchao.chen@...soc.com>
> ---
>  drivers/mmc/core/queue.c   | 6 +-----
>  drivers/mmc/host/mmc_hsq.c | 1 +
>  drivers/mmc/host/mmc_hsq.h | 7 +++++++
>  include/linux/mmc/host.h   | 1 +
>  4 files changed, 10 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/mmc/core/queue.c b/drivers/mmc/core/queue.c
> index b396e3900717..a0a2412f62a7 100644
> --- a/drivers/mmc/core/queue.c
> +++ b/drivers/mmc/core/queue.c
> @@ -260,11 +260,7 @@ static blk_status_t mmc_mq_queue_rq(struct blk_mq_hw_ctx *hctx,
>                 }
>                 break;
>         case MMC_ISSUE_ASYNC:
> -               /*
> -                * For MMC host software queue, we only allow 2 requests in
> -                * flight to avoid a long latency.
> -                */
> -               if (host->hsq_enabled && mq->in_flight[issue_type] > 2) {
> +               if (host->hsq_enabled && mq->in_flight[issue_type] > host->hsq_depth) {
>                         spin_unlock_irq(&mq->lock);
>                         return BLK_STS_RESOURCE;
>                 }
> diff --git a/drivers/mmc/host/mmc_hsq.c b/drivers/mmc/host/mmc_hsq.c
> index 424dc7b07858..7b3952721c17 100644
> --- a/drivers/mmc/host/mmc_hsq.c
> +++ b/drivers/mmc/host/mmc_hsq.c
> @@ -337,6 +337,7 @@ int mmc_hsq_init(struct mmc_hsq *hsq, struct mmc_host *mmc)
>         hsq->mmc = mmc;
>         hsq->mmc->cqe_private = hsq;
>         mmc->cqe_ops = &mmc_hsq_ops;
> +       mmc->hsq_depth = HSQ_MAX_DEPTH;
>
>         for (i = 0; i < HSQ_NUM_SLOTS; i++)
>                 hsq->tag_slot[i] = HSQ_INVALID_TAG;
> diff --git a/drivers/mmc/host/mmc_hsq.h b/drivers/mmc/host/mmc_hsq.h
> index 1808024fc6c5..795f6b9421d7 100644
> --- a/drivers/mmc/host/mmc_hsq.h
> +++ b/drivers/mmc/host/mmc_hsq.h
> @@ -5,6 +5,13 @@
>  #define HSQ_NUM_SLOTS  64
>  #define HSQ_INVALID_TAG        HSQ_NUM_SLOTS
>
> +/*
> + * For MMC host software queue, we usually allow 2 requests in
> + * flight to avoid a long latency. But we can adjust hsq->depth
> + * according to the actual situation.
> + */
> +#define HSQ_MAX_DEPTH  2
> +
>  struct hsq_slot {
>         struct mmc_request *mrq;
>  };
> diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
> index 461d1543893b..1fd8b1dd8698 100644
> --- a/include/linux/mmc/host.h
> +++ b/include/linux/mmc/host.h
> @@ -520,6 +520,7 @@ struct mmc_host {
>
>         /* Host Software Queue support */
>         bool                    hsq_enabled;
> +       int                     hsq_depth;
>
>         u32                     err_stats[MMC_ERR_MAX];
>         unsigned long           private[] ____cacheline_aligned;
> --
> 2.17.1
>