Subject: [RFC PATCH v2 0/2] io_uring: add napi busy polling support

From: Stefan Roesch <[email-masked]>
Date: Mon, 7 Nov 2022 09:52:38 -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:
- 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 (2):
  io_uring: add napi busy polling support
  io_uring: add api to set napi busy poll timeout.

 include/linux/io_uring_types.h |   6 +
 include/uapi/linux/io_uring.h  |   4 +
 io_uring/io_uring.c            | 262 +++++++++++++++++++++++++++++++++
 io_uring/napi.h                |  22 +++
 io_uring/poll.c                |   3 +
 io_uring/sqpoll.c              |   9 ++
 6 files changed, 306 insertions(+)
 create mode 100644 io_uring/napi.h

base-commit: f0c4d9fc9cc9462659728d168387191387e903cc
-- 
2.30.2