Re: [PATCH v5 08/10] scsi: ufshpb: Limit the number of inflight map requests

[Can Guo <cang@codeaurora.org>]

On 2021-03-02 21:25, Avri Altman wrote:
> in host control mode the host is the originator of map requests. To not

in -> In

Thanks,
Can Guo.

> flood the device with map requests, use a simple throttling mechanism
> that limits the number of inflight map requests.
> 
> Signed-off-by: Avri Altman <avri.altman@wdc.com>
> ---
>  drivers/scsi/ufs/ufshpb.c | 11 +++++++++++
>  drivers/scsi/ufs/ufshpb.h |  1 +
>  2 files changed, 12 insertions(+)
> 
> diff --git a/drivers/scsi/ufs/ufshpb.c b/drivers/scsi/ufs/ufshpb.c
> index 89a930e72cff..74da69727340 100644
> --- a/drivers/scsi/ufs/ufshpb.c
> +++ b/drivers/scsi/ufs/ufshpb.c
> @@ -21,6 +21,7 @@
>  #define READ_TO_MS 1000
>  #define READ_TO_EXPIRIES 100
>  #define POLLING_INTERVAL_MS 200
> +#define THROTTLE_MAP_REQ_DEFAULT 1
> 
>  /* memory management */
>  static struct kmem_cache *ufshpb_mctx_cache;
> @@ -750,6 +751,14 @@ static struct ufshpb_req
> *ufshpb_get_map_req(struct ufshpb_lu *hpb,
>  	struct ufshpb_req *map_req;
>  	struct bio *bio;
> 
> +	if (hpb->is_hcm &&
> +	    hpb->num_inflight_map_req >= THROTTLE_MAP_REQ_DEFAULT) {
> +		dev_info(&hpb->sdev_ufs_lu->sdev_dev,
> +			 "map_req throttle. inflight %d throttle %d",
> +			 hpb->num_inflight_map_req, THROTTLE_MAP_REQ_DEFAULT);
> +		return NULL;
> +	}
> +
>  	map_req = ufshpb_get_req(hpb, srgn->rgn_idx, REQ_OP_SCSI_IN);
>  	if (!map_req)
>  		return NULL;
> @@ -764,6 +773,7 @@ static struct ufshpb_req
> *ufshpb_get_map_req(struct ufshpb_lu *hpb,
> 
>  	map_req->rb.srgn_idx = srgn->srgn_idx;
>  	map_req->rb.mctx = srgn->mctx;
> +	hpb->num_inflight_map_req++;
> 
>  	return map_req;
>  }
> @@ -773,6 +783,7 @@ static void ufshpb_put_map_req(struct ufshpb_lu 
> *hpb,
>  {
>  	bio_put(map_req->bio);
>  	ufshpb_put_req(hpb, map_req);
> +	hpb->num_inflight_map_req--;
>  }
> 
>  static int ufshpb_clear_dirty_bitmap(struct ufshpb_lu *hpb,
> diff --git a/drivers/scsi/ufs/ufshpb.h b/drivers/scsi/ufs/ufshpb.h
> index b49e9a34267f..d83ab488688a 100644
> --- a/drivers/scsi/ufs/ufshpb.h
> +++ b/drivers/scsi/ufs/ufshpb.h
> @@ -212,6 +212,7 @@ struct ufshpb_lu {
>  	struct ufshpb_req *pre_req;
>  	int num_inflight_pre_req;
>  	int throttle_pre_req;
> +	int num_inflight_map_req;
>  	struct list_head lh_pre_req_free;
>  	int cur_read_id;
>  	int pre_req_min_tr_len;