Subject: [RFC PATCH v3 0/3] io_uring: add napi busy polling support

From: Stefan Roesch <[email-masked]>
Date: Mon, 14 Nov 2022 23:08:57 -0800

This adds the napi busy polling support in io_uring.c. It adds a new
napi_list to the io_ring_ctx structure. This list contains the list of
napi_id's that are currently enabled for busy polling. This list is
used to determine which napi id's enabled busy polling.

To set the new napi busy poll timeout, a new io-uring api has been
added. It sets the napi busy poll timeout for the corresponding ring.

There is also a corresponding liburing patch series, which enables this
feature. The name of the series is "liburing: add add api for napi busy
poll timeout". It also contains two programs to test the this.

Testing has shown that the round-trip times are reduced to 38us from
55us by enabling napi busy polling with a busy poll timeout of 100us.

Changes:
- V3:
  - Refreshed to 6.1-rc5
  - Added a new io-uring api for the prefer napi busy poll api and wire
    it to io_napi_busy_loop().
  - Removed the unregister (implemented as register)
  - Added more performance results to the first commit message.
- V2:
  - Add missing defines if CONFIG_NET_RX_BUSY_POLL is not defined
  - Changes signature of function io_napi_add_list to static inline
    if CONFIG_NET_RX_BUSY_POLL is not defined
  - define some functions as static

Signed-off-by: Stefan Roesch <[email-masked]>

Stefan Roesch (3):
  io_uring: add napi busy polling support
  io_uring: add api to set napi busy poll timeout.
  io_uring: add api to set napi prefer busy poll

 include/linux/io_uring_types.h |   8 +
 include/uapi/linux/io_uring.h  |   4 +
 io_uring/io_uring.c            | 278 +++++++++++++++++++++++++++++++++
 io_uring/napi.h                |  22 +++
 io_uring/poll.c                |   3 +
 io_uring/sqpoll.c              |  10 ++
 6 files changed, 325 insertions(+)
 create mode 100644 io_uring/napi.h

base-commit: 094226ad94f471a9f19e8f8e7140a09c2625abaa
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2.30.2