Hi,
Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> writes:
> 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?
I didn't know that was even plausible :-) Anyway, I'll update, but while
at that, so I use for bcdUSB instead of speed as Oliver suggested ? I
mean, a USB3 stick running on high-speed can also support 2048 max
sectors, right ?
let me know
--
balbi
Attachment:
signature.asc
Description: PGP signature
