this now has 5 args, eth1 eth2 threadcount mtu time
eth1 and eth2 the interface names
threadcound should be total expected bandwidth/10 then you might need to optimise, going above the number of actual cores is not a great idea in general, and if you are using QSF's then a minimum of 4 is recomended.
10G = 1
40G = 4
100G = 8 or 12
mtu is usually 1500 but can be set upto 9000 usually - see jumbo frames for more info online. not all NIC's/Networks support larger frame sizes.
time - in seconds for longer or shorter testing.
also added the interval of 10 for anything longer to give some feedback so you can see it's actually running.
1G = 940Mb/s
10G = 9.3Gb/s
40G = 37.5 Gb/s