Re: [PATCH 2/4] scsi: never drop to untagged mode during queue ramp down

[Hannes Reinecke <hare@suse.de>]

On 11/24/2014 03:36 PM, Christoph Hellwig wrote:
> Dropping to untagged mode when ramping down a queue due to QUEUE FULL
> events has two problems:
> 
>  - nothing in the midlayer or drivers ever moves back to tagged mode
>    during queue ramp up.
>  - cmd_per_lun isn't the untagged queue depth for many modern drivers
>    that can handle multiple untagged commands, and this is the only
>    place in the midlayer assuming that.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  drivers/scsi/scsi.c | 6 ------
>  1 file changed, 6 deletions(-)
> 
> diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
> index 72282ae..6b0d524 100644
> --- a/drivers/scsi/scsi.c
> +++ b/drivers/scsi/scsi.c
> @@ -820,12 +820,6 @@ int scsi_track_queue_full(struct scsi_device *sdev, int depth)
>  
>  	if (sdev->last_queue_full_count <= 10)
>  		return 0;
> -	if (sdev->last_queue_full_depth < 8) {
> -		/* Drop back to untagged */
> -		scsi_set_tag_type(sdev, 0);
> -		scsi_change_queue_depth(sdev, sdev->host->cmd_per_lun);
> -		return -1;
> -	}
>  
>  	return scsi_change_queue_depth(sdev, depth);
>  }
> 
Reviewed-by: Hannes Reinecke <hare@suse.de>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		      zSeries & Storage
hare@suse.de			      +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: J. Hawn, J. Guild, F. Imendörffer, HRB 21284 (AG Nürnberg)
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