Machine A (Intel 82573L) Xeon 2.6Ghz
Machine B (Intel 82574L) i7 2.6Ghz
Thus the Machine A is a generation or two behind Machine B in both CPU and NIC but thats what we have to work with.
First up is the Send histograms, in both directions A->B and B->A
Machine A send
Machine B send
As you can see Machine B kicks Machine A`s ass by the tune of say, 5-600ns. How much of this is NIC generation and how much is CPU generation is unclear, no doubt both contribute.
And on the other side, Recv first B->A and A->B look like(below)
Machine B recv
And again we see Machine B kicking Machine A`s ass not quite x2 improvement but not far off!. In anycase it looks far better than the Realtek histograms which were... just abysmal and we`ve now got a baseline to work with.
Next up is looking at the round trip latency meaning A->B->A which assuming the network switch dosent suck(too much.... its old) we should expect around 1300ns(A send) + 500ns(B recv) + 750ns(B send) + 900ns(A recv) totaling in ... around 3450 round trip - quite a long time really.
Lets see what it clocks in as.