[RFC] Patch to add Software/Generic Segmentation Offload (GSO) support in FreeBSD

[Freddie Cash]

On Thu, Sep 18, 2014 at 7:16 AM, Stefano Garzarella <
stefanogarzarella at gmail.com> wrote:

> I saw the discussion about TSO, but the GSO is a software
> implementation unrelated with the hardware.
> Furthermore, if the TSO is enabled (and supported by the NIC), the GSO is
> not executed, because is useless.
>
> After the execution of the GSO, the packets, that are passed to the device
> driver, are smaller (or equal) than MTU, so the TSO is unnecessary. For
> this reason the GSO doesn't look neither "ifp->if_hw_tsomax" nor hardware
> segment limits.
>
> The GSO is very useful when you can't use the TSO.
>

​How does GSO affect IPFW, specifically the libalias(3)-based, in-kernel
NAT?  The ipfw(8) man page mentions that it doesn't play nicely with
hardware-based TSO, and that one should disable TSO when using IPFW NAT.

Will the software-based GSO play nicely with IPFW NAT?​  Will it make any
difference to packet throughput through IPFW?

Or is it still way too early in development to be worrying about such
things?  :)

-- 
Freddie Cash
fjwcash at gmail.com