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
[off-list ref] wrote:

quoted

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