On Wed, 13 Apr 2016, Felipe Balbi wrote:
> USB3 devices, because they are much newer, have much
> less chance of having issues with larger transfers.
>
> We still keep a limit because anything above 2048
> sectors really rendered negligible speed
> improvements, so we will simply ignore
> that. Transferring 1MiB should already give us
> pretty good performance.
>
> Signed-off-by: Felipe Balbi <felipe.balbi@xxxxxxxxxxxxxxx>
> ---
> drivers/usb/storage/scsiglue.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/drivers/usb/storage/scsiglue.c b/drivers/usb/storage/scsiglue.c
> index 9da1fb3d0ff4..2bb6a88858ea 100644
> --- a/drivers/usb/storage/scsiglue.c
> +++ b/drivers/usb/storage/scsiglue.c
> @@ -127,6 +127,11 @@ static int slave_configure(struct scsi_device *sdev)
> if (queue_max_hw_sectors(sdev->request_queue) > max_sectors)
> blk_queue_max_hw_sectors(sdev->request_queue,
> max_sectors);
> + } else if (us->pusb_dev->speed >= USB_SPEED_SUPER) {
> + /* USB3 devices will be limited to 2048 sectors. This gives us
> + * better throughput on most devices.
> + */
> + blk_queue_max_hw_sectors(sdev->request_queue, 2048);
> } else if (sdev->type == TYPE_TAPE) {
> /* Tapes need much higher max_sector limits, so just
> * raise it to the maximum possible (4 GB / 512) and
Argh! This has the same kind of problem as before. What will happen
when somebody has a USB-3 tape drive?
Alan Stern
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