Re: Alternative title
"These include better use of scatter/gather features of the NIC or DMA "
Which NIC or DMA?
If you tie the S/W to specific H/W, e.g. a particular model of NIC then you lose the ability to plug in different H/W. If you provide for alternative H/W you end up with a modular structure which has its own overhead. I'm not saying that something which has grown at the rate the Linux kernel has is going to be the result of a whole series of ideal decisions (I can think of a few I disagree with) but if you try to do everything there are going to be trade-offs.