http://bugzilla.kernel.org/show_bug.cgi?id=12207 ------- Comment #12 from anonymous@xxxxxxxxxxxxxxxxxxxx 2008-12-23 07:33 ------- Reply-To: James.Bottomley@xxxxxxxxxxxxxxxxxxxxx On Tue, 2008-12-23 at 08:55 -0600, James Bottomley wrote: > > ------- Comment #6 from stern@xxxxxxxxxxxxxxxxxxx 2008-12-23 05:59 ------- > > You can change the max_sectors setting through sysfs. However the last time I > > looked, the block layer limited max_sectors to 512 KB or something on that > > order, so you can't get too much improvement. > > > > Why is a limit of 120 KB unreasonably small? All it means is that you have to > > use more system calls to transfer the same amount of data. Is anything wrong > > with that? > > Tapes need large block sizes. > > We can accommodate both: Just check for TYPE_TAPE in the > slave_configure() and bump the limit back up. Any USB tape that doesn't > do large block transfers will be truly broken. Following up on this, does this fix it? I notice that Linus was the one who actually committed this change in 2.6.0-test10, so it's been in the entire 2.6 release. James --- diff --git a/drivers/usb/storage/scsiglue.c b/drivers/usb/storage/scsiglue.c index 09779f6..ae4b01c 100644 --- a/drivers/usb/storage/scsiglue.c +++ b/drivers/usb/storage/scsiglue.c @@ -127,7 +127,12 @@ static int slave_configure(struct scsi_device *sdev) if (sdev->request_queue->max_sectors > max_sectors) blk_queue_max_sectors(sdev->request_queue, max_sectors); - } + } else if (sdev->type == TYPE_TAPE) + /* Tapes need much higher max sector transfers, so just + * raise it to the maximum possible and let the queue + * segment size sort out the real limit + */ + blk_queue_max_sectors(sdev->request_queue, 0xFFFF); /* We can't put these settings in slave_alloc() because that gets * called before the device type is known. Consequently these -- Configure bugmail: http://bugzilla.kernel.org/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are the assignee for the bug, or are watching the assignee. -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
