Alan Stern <[email protected]> writes: > On Mon, 11 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 <[email protected]> >> --- >> drivers/usb/storage/scsiglue.c | 16 +++++++++++----- >> 1 file changed, 11 insertions(+), 5 deletions(-) >> >> diff --git a/drivers/usb/storage/scsiglue.c b/drivers/usb/storage/scsiglue.c >> index 9da1fb3d0ff4..4512cf78a284 100644 >> --- a/drivers/usb/storage/scsiglue.c >> +++ b/drivers/usb/storage/scsiglue.c >> @@ -115,13 +115,19 @@ static int slave_configure(struct scsi_device *sdev) >> { >> struct us_data *us = host_to_us(sdev->host); >> >> - /* Many devices have trouble transferring more than 32KB at a time, >> - * while others have trouble with more than 64K. At this time we >> - * are limiting both to 32K (64 sectores). >> - */ >> - if (us->fflags & (US_FL_MAX_SECTORS_64 | US_FL_MAX_SECTORS_MIN)) { >> + 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 (us->fflags & (US_FL_MAX_SECTORS_64 | US_FL_MAX_SECTORS_MIN)) >> { >> unsigned int max_sectors = 64; >> >> + /* Many devices have trouble transferring more than 32KB at a >> time, >> + * while others have trouble with more than 64K. At this time we >> + * are limiting both to 32K (64 sectores). >> + */ >> + >> if (us->fflags & US_FL_MAX_SECTORS_MIN) >> max_sectors = PAGE_SIZE >> 9; >> if (queue_max_hw_sectors(sdev->request_queue) > max_sectors) > > I should have noticed this before. If something goes wrong with the > 2048-sector limit, this doesn't permit the user to override. Shouldn't > the test for USB_SPEED_SUPER go after the other FL_MAX_SECTORS tests?
you mean that a USB3 device with US_FL_MAX_SECTORS* should still respect the 64 limit ? yeah I can do that. I'll send a new version tomorrow (so I can wait for confirmation from you) -- balbi
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