[Bloat] [Codel] The challenge

[Eric Dumazet]

On Wed, 2012-05-09 at 17:47 -0400, Jim Gettys wrote:

>     2) what the NIC offload engines were doing to generate line rate
> packet trains and injecting them into the net, where they can land
> "spat" at the customer end.


If the server has 100Gb link, and the client a 1Mb link, TSO is hardly
making a difference in trains. Sending 10 consecutive 1500 bytes packets
or one 15000 bytes packets will have the same effect, unless the sender
is serving thousands of clients and a FairQueue interleaves packets.

One solution is at the producer level (TCP stack of the sender in this
case) to properly pace the transmits in MSS units given the RTT and
cwnd, supposedly done with TCP Hybla.