2017-11-14 0:50 GMT+01:00 Alexei Starovoitov [off-list ref]:

On 11/13/17 9:07 PM, Björn Töpel wrote:

quoted

2017-10-31 13:41 GMT+01:00 Björn Töpel [off-list ref]:

quoted

From: Björn Töpel <redacted>

[...]

quoted

We'll do a presentation on AF_PACKET V4 in NetDev 2.2 [1] Seoul,
Korea, and our paper with complete benchmarks will be released shortly
on the NetDev 2.2 site.

We're back in the saddle after an excellent netdevconf week. Kudos to
the organizers; We had a blast! Thanks for all the constructive
feedback.

I'll summarize the major points, that we'll address in the next RFC
below.

* Instead of extending AF_PACKET with yet another version, introduce a
  new address/packet family. As for naming had some name suggestions:
  AF_CAPTURE, AF_CHANNEL, AF_XDP and AF_ZEROCOPY. We'll go for
  AF_ZEROCOPY, unless there're no strong opinions against it.

* No explicit zerocopy enablement. Use the zeropcopy path if
  supported, if not -- fallback to the skb path, for netdevs that
  don't support the required ndos. Further, we'll have the zerocopy
  behavior for the skb path as well, meaning that an AF_ZEROCOPY
  socket will consume the skb and we'll honor skb->queue_mapping,
  meaning that we only consume the packets for the enabled queue.

* Limit the scope of the first patchset to Rx only, and introduce Tx
  in a separate patchset.

all sounds good to me except above bit.
I don't remember people suggesting to split it this way.
What's the value of it without tx?

We definitely need Tx for our use-cases! I'll rephrase, so the
idea was making the initial patch set without Tx *driver*
specific code, e.g. use ndo_xdp_xmit/flush at a later point.

So AF_ZEROCOPY, the socket parts, would have Tx support.

@John Did I recall that correctly?

quoted

* Minimize the size of the i40e zerocopy patches, by moving the driver
  specific code to separate patches.

* Do not introduce a new XDP action XDP_PASS_TO_KERNEL, instead use
  XDP redirect map call with ingress flag.

* Extend the XDP redirect to support explicit allocator/destructor
  functions. Right now, XDP redirect assumes that the page allocator
  was used, and the XDP redirect cleanup path is decreasing the page
  count of the XDP buffer. This assumption breaks for the zerocopy
  case.


Björn

quoted

We based this patch set on net-next commit e1ea2f9856b7 ("Merge
git://git.kernel.org/pub/scm/linux/kernel/git/davem/net").

Please focus your review on:

* The V4 user space interface
* PACKET_ZEROCOPY and its semantics
* Packet array interface
* XDP semantics when excuting in zero-copy mode (user space passed
  buffers)
* XDP_PASS_TO_KERNEL semantics

To do:

* Investigate the user-space ring structure’s performance problems
* Continue the XDP integration into packet arrays
* Optimize performance
* SKB <-> V4 conversions in tp4a_populate & tp4a_flush
* Packet buffer is unnecessarily pinned for virtual devices
* Support shared packet buffers
* Unify V4 and SKB receive path in I40E driver
* Support for packets spanning multiple frames
* Disassociate the packet array implementation from the V4 queue
  structure

We would really like to thank the reviewers of the limited
distribution RFC for all their comments that have helped improve the
interfaces and the code significantly: Alexei Starovoitov, Alexander
Duyck, Jesper Dangaard Brouer, and John Fastabend. The internal team
at Intel that has been helping out reviewing code, writing tests, and
sanity checking our ideas: Rami Rosen, Jeff Shaw, Ferruh Yigit, and Qi
Zhang, your participation has really helped.

Thanks: Björn and Magnus

[1]
https://urldefense.proofpoint.com/v2/url?u=https-3A__www.netdevconf.org_2.2_&d=DwIFaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=qR6oNZj1CqLATni4ibTgAQ&m=lKyFxON3kKygiOgECLBfmqRwM7ZyXFSUvLED1vP-gos&s=44jzm1W8xkGyZSZVANRygzHz6y4XHbYrYBRM-K5RhTc&e=


Björn Töpel (7):
  packet: introduce AF_PACKET V4 userspace API
  packet: implement PACKET_MEMREG setsockopt
  packet: enable AF_PACKET V4 rings
  packet: wire up zerocopy for AF_PACKET V4
  i40e: AF_PACKET V4 ndo_tp4_zerocopy Rx support
  i40e: AF_PACKET V4 ndo_tp4_zerocopy Tx support
  samples/tpacket4: added tpbench

Magnus Karlsson (7):
  packet: enable Rx for AF_PACKET V4
  packet: enable Tx support for AF_PACKET V4
  netdevice: add AF_PACKET V4 zerocopy ops
  veth: added support for PACKET_ZEROCOPY
  samples/tpacket4: added veth support
  i40e: added XDP support for TP4 enabled queue pairs
  xdp: introducing XDP_PASS_TO_KERNEL for PACKET_ZEROCOPY use

 drivers/net/ethernet/intel/i40e/i40e.h         |    3 +
 drivers/net/ethernet/intel/i40e/i40e_ethtool.c |    9 +
 drivers/net/ethernet/intel/i40e/i40e_main.c    |  837 ++++++++++++-
 drivers/net/ethernet/intel/i40e/i40e_txrx.c    |  582 ++++++++-
 drivers/net/ethernet/intel/i40e/i40e_txrx.h    |   38 +
 drivers/net/veth.c                             |  174 +++
 include/linux/netdevice.h                      |   16 +
 include/linux/tpacket4.h                       | 1502
++++++++++++++++++++++++
 include/uapi/linux/bpf.h                       |    1 +
 include/uapi/linux/if_packet.h                 |   65 +-
 net/packet/af_packet.c                         | 1252
+++++++++++++++++---
 net/packet/internal.h                          |    9 +
 samples/tpacket4/Makefile                      |   12 +
 samples/tpacket4/bench_all.sh                  |   28 +
 samples/tpacket4/tpbench.c                     | 1390
++++++++++++++++++++++
 15 files changed, 5674 insertions(+), 244 deletions(-)
 create mode 100644 include/linux/tpacket4.h
 create mode 100644 samples/tpacket4/Makefile
 create mode 100755 samples/tpacket4/bench_all.sh
 create mode 100644 samples/tpacket4/tpbench.c

--
2.11.0