From: Eric Dumazet <eduma...@google.com> Date: Mon, 18 Apr 2016 13:56:12 -0700
> 1 % packet losses are common today, and at 100Gbit speeds, this > translates to ~80,000 losses per second. If we are unlucky and > first MSS of a 45-MSS TSO is lost, we are cooking 44 MSS segments > at rtx instead of a single 44-MSS TSO packet. I'm having trouble understanding this. If the first mss is lost, then we simply chop the 45 MSS TSO skb into two pieces. The first piece is a 1 MSS chunk for the retransmit, and the second piece is remaining 44 MSS TSO skb. I am pretty sure that is what the current stack does, and regardless it is certainly what I intended it to do all those years ago when I wrote this code. :-) The only case where I can see this patch helping is when we have to retransmit multi-mss chunks. And yes indeed, it might be a useful optimization to TSO those frames rather than sending them one MSS at a time.
