On Tue, 14 Aug 2007, wim delvaux wrote: > Hi all, > > I run kubuntu feist with a 2.6.20 kernel. > > The MoBo I have produces this as output for usbtree > > /: Bus 04.Port 1: Dev 1, Class=root_hub, Drv=uhci_hcd/2p, 12M > /: Bus 03.Port 1: Dev 1, Class=root_hub, Drv=uhci_hcd/2p, 12M > /: Bus 02.Port 1: Dev 1, Class=root_hub, Drv=uhci_hcd/2p, 12M > |_ Port 1: Dev 2, If 0, Prod=Evoluent VerticalMouse 3, Class=HID, > Drv=usbhid, 1.5M > |_ Port 2: Dev 3, If 0, Prod=USB to ATA/ATAPI Bridge, Class=stor., > Drv=usb-storage, 12M > /: Bus 01.Port 1: Dev 1, Class=root_hub, Drv=uhci_hcd/2p, 12M > > This indicates that the disk connected to the USB-ata bridge at port > 2/device2 > is a full speed device. > > This confirmed by my dmesg output. > > My second USB external disk also indicates 'full speed'. > > The problem I encounter is that data transfer to my disk connected to the > usb-ata is slow. transfer rates of about 400 KB are max. In the beginning > it is fast (40 MB/Sec) but then it drops and sometimes even stalles.
That 40 MB/s is an illusion; it is the speed at which memory buffers inside your computer get filled. Once the data really starts going out to the disk the speed drops down to the correct value. 400 KB/s isn't great for full speed, but it isn't terrible either. It's about 1/3 the theoretical maximum. > The other external disk (also claimed to be full speed) seems to achieve > transfer speeds of 20-30 KB which seems OK. If 400 KB/s is bad, how come 20-30 KB/s is OK? > I also see that uhci_hcd has taken control over my USB. is that OK knowing > that my board supports usb2.0 ? Your board supports it, but have you checked your BIOS settings? Maybe you've got USB 2.0 support disabled. What does lspci reveal? Have you tried loading ehci-hcd? > If not, is it possible that the usb-ata bridge is not detected as a USB2.0 > device ? Very unlikely. You can confirm it by looking at /proc/bus/usb/devices. > If so, how can i make it detect it properly ? If the device itself reports that it only supports USB 1.1 then there's not much you can do about it. Alan Stern ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ Linux-usb-users@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-users
