Hi Laszlo, On 08/03/2014 12:40 AM, Laszlo T. wrote: >>>>>> *) usb devices return different descriptors at different speeds >>>>> >>>>> All tests were on usb2. >>>>> I don't have usb3 ports but I will try that at weekend. >>>>> >>>>> I'm curious now, am I the first one who has ever tested uas on usb2? >>>> >>>> Ni, I've tested it myself too, including running an entire distro >>>> with gnome3 from an uas disk. >>>> >>>> I'll also do some more tests with mkfs.ext4 with my uas disk enclosures >>>> as that seems to trigger things for you. But for me so far using usb2 is >>>> not a problem. >>>> >>>> Regards, >>>> >>>> Hans >>> >>> It looks stable with >>> can_queue = 65536 and qdepth = 32 >>> on usb2. >> >> That is good to hear. >> >>> Please share you result when you have chance to test with your enclosure. >> >> I've tested 2 different uas enclosures with 3 different disks on usb2, >> running mkfs.ext4 on a single partition spanning the entire disk, and >> I could not reproduce, so this seems to be specific to the jmicron >> chipset your using. Still there is little in harm in just always reducing >> the usb2 qdepth to 32, that should be plenty to keep things close to maximum >> possible throughput on usb2. >> >> I'll write a patch for this and I'll Cc. you on the patch. > > Thank you. > > I could tested the device on USB 3.0 with an unpatched 3.15.5 kernel > and unfortunately it failed with the usual error. > > > lsusb on usb3 > > Bus 002 Device 002: ID 152d:0567 JMicron Technology Corp. / JMicron > USA Technology Corp. > Device Descriptor: > bLength 18 > bDescriptorType 1 > bcdUSB 2.10 Thanks for the log, but this indicates that the device is still connected at usb-2 speed, so either you did not use an usb-3 cable, or the port you used was not superspeed capable (or it ended up falling back to usb-2 for some other reason). And since this is an otherwise unmodified kernel, that explains why you get the old troublesome behavior in this case. When connected over USB-3 I would expect this to read: bcdUSB 3.00 Another way to check the speed is to do lsusb: [hans@shalem ~]$ lsusb Bus 009 Device 002: ID 045b:021f Hitachi, Ltd Bus 009 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub Bus 008 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Note how the "Hitachi, Ltd" device is on the same Bus as the "Linux Foundation 3.0 root hub" If that is not the case for a device, then it is not connected over USB-3. Regards, Hans -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
