Re: [PATCH RFC 0/3] Support fraglist GRO/GSO

[Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>]

On Sun, Dec 23, 2018 at 08:15:40PM -0500, Willem de Bruijn wrote:
> On Fri, Dec 21, 2018 at 10:23 AM Steffen Klassert
> <steffen.klassert@secunet.com> wrote:
> >
> > This patchset adds support to do GRO/GSO by chaining packets
> > of the same flow at the SKB frag_list pointer. This avoids
> > the overhead to merge payloads into one big packet, and
> > on the other end, if GSO is needed it avoids the overhead
> > of splitting the big packet back to the native form.
> >
> > Patch 1 prepares GSO to handle fraglist GSO packets.
> > Patch 2 adds the core infrastructure to do fraglist
> > GRO/GSO. Patch 3 enables IPv4 UDP to use fraglist
> > GRO/GSO if no GRO supported socket is found.
> >
> > I have only forwarding performance measurements so far:
> >
> > I used used my IPsec forwarding test setup for this:
> >
> >            ------------         ------------
> >         -->| router 1 |-------->| router 2 |--
> >         |  ------------         ------------  |
> >         |                                     |
> >         |       --------------------          |
> >         --------|Spirent Testcenter|<----------
> >                 --------------------
> >
> > net-next (December 10th):
> >
> > Single stream UDP frame size 1460 Bytes: 1.341.700 fps (15.67 Gbps).
> >
> > ----------------------------------------------------------------------
> >
> > net-next (December 10th) + hack to enable forwarding for standard UDP GRO:
> >
> > Single stream UDP frame size 1460 Bytes: 1.651.200 fps (19.28 Gbps).
> >
> > ----------------------------------------------------------------------
> >
> > net-next (December 10th) + fraglist UDP GRO/GSO:
> >
> > Single stream UDP frame size 1460 Bytes: 2.742.500 fps (32.03 Gbps).
> 
> That's an impressive speed-up over regular UDP GRO. Definitely worth
> looking into more, then.
> 
> Sorry for the delay. I still haven't parsed everything yet, but a few
> high level questions and comments.
> 
> This sounds similar to GSO_BY_FRAGS as used by SCTP. Can perhaps reuse
> that or deduplicate a bit. It is nice that this uses a separate
> skb_segment_list function; skb_segment is arguably too complex as is
> already.

This patchset looks like a more whole version of what GSO_BY_FRAGS is,
and I like it.  It should be easy to adapt SCTP to use these patches
instead. I can do it if needed.

  Marcelo