Re: IPSEC disables TSO

On 8/16/07, Andrew Gallatin <gallatin_at_cs.duke.edu> wrote:
>
> When tracking down an mxge 10GbE performance issue, I noticed that
> simply compiling IPSEC into the kernel totally destroys 10GbE transmit
> performance because it will silently disable TSO.
>
> The problem seems to be at least that the test on line 463 of
> tcp_output.c (tp->t_inpcb->inp_sp == NULL) will always be
> false.   If I comment that line out, TSO works as normal
> (though I have no idea what would happen on an IPSEC connection).
>
> Is there some way to make this not happen?  I believe that the mxge
> user simply wanted to run some handful of applications through ipsec
> tunnels (perhaps even on a different NIC entirely).

IPSEC encrypts the TCP header - how is the card going to do TSO?

 -Kip