On Friday 28 August 2009 01:14:42 pm Jon Fairbairn wrote: > I'm experimenting with a virtual router. I did this a few years ago with > Xen and it worked well enough, but then fedora changed and it stopped > working, so I gave up for a while. Now I have a machine that supports > hardware virtualisation, I thought I'd try again. > > The setup was done through virt-manager. The network between the host > and guest is a virtual bridge. What I've been trying to do is to assign > a USB cable modem to the guest, This is probably your problem here. KVM only emulates a usb1.1 controller, and from all reports, it doesn't really do that very well. There have been numerous reports of poor performance even for a usb1.1 device. You should check the archives to see if there was ever any kind of tips or resolution to some of those problems. > and connect to the internet through > that. I'd expect some degradation in performance, especially since > there's a firewall on both the virtual router and on the host. Here's > some figures wgetting a 12802500 byte file thrice from a nearby web > server: > > Via hardware router: 1009K/s 1008K/s 1010K/s (12 or 13s) > Cable modem on host: 1.00M/s 1.00M/s 1.00M/s (ditto) > > (wait for it) > > Via virtual router, assigned usb: 21.1K/s (9m 58s!) > > Now, as I said, I expected some performance hit doing it this way, but a > factor of fifty takes the biscuit. > > What can be wrong? > > * * * > > Details: > > "Cable modem on host" above just means that I attached the cable modem > to the host and configured it as a network device in the usual way. > > From the host to the guest I get about 12MB/s using scp, from the guest > to the host (initiated from the host) I get 7MB/s. > > The host is AMD Athlon(tm) 64 X2 Dual Core Processor 4400+ with 6G of > RAM of which 256M is assigned to the guest (the hardware version only > has 188M) neither virtual nor hardware router has any swap. > > The hardware router is the same kernel and nearly (modulo IP addresses > etc) the same configuration as the virtual router, running on an old ibm > pc (500MHz pentium III). > > kernel on host: 2.6.29.6-217.2.16.fc11.x86_64 > kernel on routers: 2.6.29.6-217.2.8.fc11.i586 > > All running fedora 11 (though the routers are very much cut down > installations). > > qemu-kvm-0.10.6 > libvirt-0.6.2-15.1.fc11.x86_64 > > libvirt uses this command to start the virtual machine: > > LC_ALL=C PATH=/sbin:/usr/sbin:/bin:/usr/bin /usr/bin/qemu-kvm -S -M pc \ > -m 256 -smp 1 -name monogramme-virtual \ > -uuid [redacted] -monitor pty \ > -pidfile /var/run/libvirt/qemu//monogramme-virtual.pid \ > -boot d \ > -drive file=/[wherever]/livecd-fedora-monogramme.iso,\ > if=ide,media=cdrom,index=2 \ > -net nic,macaddr=54:52:00:14:4f:18,vlan=0 \ > -net tap,fd=11,vlan=0 -serial pty -parallel none -usb -vnc 127.0.0.1:0 \ > -k en-gb \ > -usbdevice host:0bb2:6098 > > 0bb2:6098 = Ambit Microsystems Corp. USB Cable Modem (a usb 1.1 device) > > Selinux is on on both machines. > > I can't think of anything else relevant at the moment. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
