Re: [PATCH 1/3] scsi_debug: Increase the reported optimal transfer length

[Douglas Gilbert <dgilbert@interlog.com>]

On 15-12-16 05:53 PM, Martin K. Petersen wrote:
> The OPTIMAL TRANSFER LENGTH reported by scsi_debug is 64 blocks which
> translates to 32KB with the default logical block size. That's much
> lower than what real storage devices typically report (256KB to 1MB).
>
> Bump the optimal transfer length to 1024 blocks.
>
> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Acked-by: Douglas Gilbert <dgilbert@interlog.com>

> ---
>   drivers/scsi/scsi_debug.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
> index d09d60293c27..b80b037f2982 100644
> --- a/drivers/scsi/scsi_debug.c
> +++ b/drivers/scsi/scsi_debug.c
> @@ -129,7 +129,7 @@ static const char *scsi_debug_version_date = "20141022";
>   #define DEF_NO_LUN_0   0
>   #define DEF_NUM_PARTS   0
>   #define DEF_OPTS   0
> -#define DEF_OPT_BLKS 64
> +#define DEF_OPT_BLKS 1024
>   #define DEF_PHYSBLK_EXP 0
>   #define DEF_PTYPE   0
>   #define DEF_REMOVABLE false
> @@ -4140,7 +4140,7 @@ MODULE_PARM_DESC(no_lun_0, "no LU number 0 (def=0 -> have lun 0)");
>   MODULE_PARM_DESC(no_uld, "stop ULD (e.g. sd driver) attaching (def=0))");
>   MODULE_PARM_DESC(num_parts, "number of partitions(def=0)");
>   MODULE_PARM_DESC(num_tgts, "number of targets per host to simulate(def=1)");
> -MODULE_PARM_DESC(opt_blks, "optimal transfer length in block (def=64)");
> +MODULE_PARM_DESC(opt_blks, "optimal transfer length in blocks (def=1024)");
>   MODULE_PARM_DESC(opts, "1->noise, 2->medium_err, 4->timeout, 8->recovered_err... (def=0)");
>   MODULE_PARM_DESC(physblk_exp, "physical block exponent (def=0)");
>   MODULE_PARM_DESC(ptype, "SCSI peripheral type(def=0[disk])");
>