Comment 21 for bug 130075

for me the error is not occuring any more when I load the module with

options forcedeth max_interrupt_work=200

but it seems to be ignored during boot. So I have do the following in /etc/rc.local:

rmmod forcedeth && modprobe forcedeth && /etc/init.d/networking restart

now iperf runs at full gigabit speed without any errors!