On Fri, 24 Jul 2009, cihan öztürk wrote: > Hi all, > I am trying to test the maximum USB bandwidth that can be allocated to > a class of USB devices. I am looking forward to removing all other USB > devices on my system, so that I am sure that the Host Controller > doesn't reserve any bandwith to other devices. You don't have to remove all the other USB devices on your system, only the other USB devices attached to the same host controller. Different host controllers are on separate buses and therefore have independent bandwidth. > lsusb command outputs: > Bus 005 Device 004: ID 05e1:0501 Syntek Semiconductor Co., Ltd WebCam, > Chipset DC-1125 similar to 174f:a311 - Asus F2F, F2J, F3J, F3T, G1, Z53JA > Bus 005 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub > Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub > Bus 003 Device 002: ID 0b05:1712 ASUSTek Computer, Inc. BT-183 Bluetooth > 2.0+EDR adapter > Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub > Bus 002 Device 002: ID 046d:c019 Logitech, Inc. Optical Tilt Wheel Mouse > Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub > Bus 001 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub > > The mouse is easy to remove, but the other two devices are integrated > to my notebook. I have searched the forums but could not find how to > remove them from my system. I am also not sure if I do need to > remove them, since they may not be reserved any bandwidth while they > are not in use. The webcam on bus 5 is definely not in use, because > I succesfully remove its driver(assuming it's driven by stkwebcam) > from system. But even then it's still in lsusb list. > But when I try to remove any bluetooth related drivers(ie. btusb), it > gives the error "module in use". > > Also, lsmod |grep usb gives: > btusb 11856 3 > bluetooth 52740 11 sco,rfcomm,bnep,l2cap,btusb > usbhid 24480 0 > hid 42048 1 usbhid > usbcore 159664 6 stkwebcam,btusb,usbhid,ehci_hcd,uhci_hcd > > Lastly, I observed the traffic at buses 3 and 5 with usbmon while > communicating with my own devices on other buses, and generated > output files for buses 3 and 5 were empty. Does that mean that no > bandwidth was reserved for them by the HC, so that they don't interfere > my USB tests? Not necessarily. usbmon displays information when a transfer begins and when it ends, but not while it is in progress. There could be long-running transfers in progress on buses 3 and 5, and you wouldn't see them. But if the webcam was the only device on bus 5 and you removed its driver then it couldn't be using any bandwidth. However, if your devices are all on other buses then you shouldn't care how much bandwidth is being used on buses 3 and 5. Alan Stern -- 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
