Re: [Qemu-devel] Performance of USB2.0

[Til Obes <til@obes.name>]

Hi.

Am 31.10.2011 13:46, schrieb Hans de Goede:
> If you're using libvirt to start qemu, then it will also pass
> -usb to qemu, so you will have both a usb-1 (uhci) and a usb-2
> (ehci) controller inside your vm, since your hostdev xml code does
> not specify a bus the hostdev will likely get connected to the first
> usb bus which is the one attached to the uhci controller, although
> your lsusb output suggests otherwise (to my surprise).
 >
 > So assuming that I'm reading your lsusb output correct, the device
 > does seem to be connected to the virtual ehci controller rather then
 > to the virtual uhci controller, which more or less rules that out
 > as the cause.


The kernel output says:
router:~# dmesg|grep usb
[    0.418314] usbcore: registered new interface driver usbfs
[    0.418401] usbcore: registered new interface driver hub
[    0.419256] usbcore: registered new device driver usb
[    0.488137] usb usb1: New USB device found, idVendor=1d6b, idProduct=0002
[    0.488144] usb usb1: New USB device strings: Mfr=3, Product=2, 
SerialNumber=1
[    0.488150] usb usb1: Product: EHCI Host Controller
[    0.488155] usb usb1: Manufacturer: Linux 2.6.32-5-amd64 ehci_hcd
[    0.488160] usb usb1: SerialNumber: 0000:00:07.0
[    0.488437] usb usb1: configuration #1 chosen from 1 choice
[    1.155604] usb 1-1: new high speed USB device using ehci_hcd and 
address 2
[    1.665760] usb 1-1: New USB device found, idVendor=9710, idProduct=7830
[    1.665781] usb 1-1: New USB device strings: Mfr=1, Product=2, 
SerialNumber=3
[    1.665784] usb 1-1: Product: USB-MAC Controller
[    1.665786] usb 1-1: Manufacturer: Moschip Semiconductor
[    1.665787] usb 1-1: SerialNumber: 3b0c00d1
[    1.665886] usb 1-1: configuration #1 chosen from 1 choice
[    1.877906] usb 1-1: applying rev.C fixup
[    1.890249] usb 1-1: applying rev.C fixup
[    1.905011] eth2: register 'MOSCHIP usb-ethernet driver' at 
usb-0000:00:07.0-1, MOSCHIP 7830/7730 usb-NET adapter, 00:13:3b:0c:00:d1
[    1.905028] usbcore: registered new interface driver MOSCHIP 
usb-ethernet driver

So it should work with my configuration...


> This means that the likely cause is just that usb emulation / pass
> through causes quite a bit of overhead, which is not unexpected since
> both the usb protocol and the ehci controller interface are both quite
> hard to emulate.

But 6Mbit from 480MBit is quite low, at least 100MBit should be 
realistic or? How can i debug this?

> It is likely better to just use the usb nic directly from the host,
> and then pass it through the virtio-net using bridging.

Well the cable modem is only talking to the first mac address it gets.
In my setup eth1 is the bridged nic to the cable box and it isnt
working. Any suggestions how to solve this?

Regards Til