On 4/19/24 12:08, Pavel Begunkov wrote:
Please, don't take directly, conflicts with io_uring.

When everyone is happy with the patches, Jens and Jakub will hopefully
help to merge them. E.g. first staging net/ specific changes [1] and then
handling all conflicts on the io_uring side.

[1] https://github.com/isilence/linux.git iou-sendzc/notif-stacking-v2-netonly


To have per request buffer notifications each zerocopy io_uring send
request allocates a new ubuf_info. However, as an skb can carry only
one uarg, it may force the stack to create many small skbs hurting
performance in many ways.

The patchset implements notification, i.e. an io_uring's ubuf_info
extension, stacking. It attempts to link ubuf_info's into a list,
allowing to have multiple of them per skb.

liburing/examples/send-zerocopy shows up 6 times performance improvement
for TCP with 4KB bytes per send, and levels it with MSG_ZEROCOPY. Without
the patchset it requires much larger sends to utilise all potential.

bytes  | before | after (Kqps)
1200   | 195    | 1023
4000   | 193    | 1386
8000   | 154    | 1058

The patches are on top of net-next + io_uring-next:

https://github.com/isilence/linux.git iou-sendzc/notif-stacking-v2

First two patches based on net-next:

https://github.com/isilence/linux.git iou-sendzc/notif-stacking-v2-netonly

v2: convert xen-netback to ubuf_info_ops (patch 1)
     drop two separately merged io_uring patches

Pavel Begunkov (4):
   net: extend ubuf_info callback to ops structure
   net: add callback for setting a ubuf_info to skb
   io_uring/notif: simplify io_notif_flush()
   io_uring/notif: implement notification stacking

  drivers/net/tap.c                   |  2 +-
  drivers/net/tun.c                   |  2 +-
  drivers/net/xen-netback/common.h    |  5 +-
  drivers/net/xen-netback/interface.c |  2 +-
  drivers/net/xen-netback/netback.c   | 11 ++--
  drivers/vhost/net.c                 |  8 ++-
  include/linux/skbuff.h              | 21 +++++---
  io_uring/notif.c                    | 83 +++++++++++++++++++++++++----
  io_uring/notif.h                    | 12 ++---
  net/core/skbuff.c                   | 36 ++++++++-----
  10 files changed, 134 insertions(+), 48 deletions(-)


--
Pavel Begunkov

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