[PATCH io_uring-next/net-next v2 0/4] implement io_uring notification (ubuf_info) stacking

[Pavel Begunkov <asml.silence@gmail.com>]

Please, don't take directly, conflicts with io_uring.

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(-)

-- 
2.44.0