[RFC PATCH v3 0/4] liburing: add api for napi busy poll timeout

[Stefan Roesch <shr@devkernel.io>]

This adds three new api's to set/clear the napi busy poll timeout and to set
the napi prefer busy poll setting. The three new functions are called:
- io_uring_napi_register_busy_poll_timeout,
- io_uring_napi_unregister_busy_poll_timeout,
- io_uring_register_napi_prefer_busy_poll.

The patch series also contains the documentation for the three new functions
and two example programs. The client program is called napi-busy-poll-client
and the server program napi-busy-poll-server. The client measures the
roundtrip times of requests.

There is also a kernel patch "io-uring: support napi busy poll" to enable
this feature on the kernel side.

Changes:
- V3:
  - Updated liburing.map file
  - Moved example programs from the test directory to the example directory.
    The two example programs don't fit well in the test category and need to
    be run from separate hosts.
  - Added the io_uring_register_napi_prefer_busy_poll API.
  - Added the call to io_uring_register_napi_prefer_busy_poll to the example
    programs
  - Updated the documentation
- V2:
  - Updated the liburing.map file for the two new functions.
    (added a 2.4 section)
  - Added a description of the new feature to the changelog file
  - Fixed the indentation of the longopts structure
  - Used defined exit constants
  - Fixed encodeUserData to support 32 bit builds


Signed-off-by: Stefan Roesch <shr@devkernel.io>

Stefan Roesch (4):
  liburing: add api to set napi busy poll settings
  liburing: add documentation for new napi busy polling
  liburing: add test programs for napi busy poll
  liburing: update changelog with new feature

 .gitignore                                    |   2 +
 CHANGELOG                                     |   3 +
 examples/Makefile                             |   2 +
 examples/napi-busy-poll-client.c              | 432 ++++++++++++++++++
 examples/napi-busy-poll-server.c              | 380 +++++++++++++++
 ...io_uring_register_napi_busy_poll_timeout.3 |  35 ++
 man/io_uring_register_napi_prefer_busy_poll.3 |  35 ++
 ..._uring_unregister_napi_busy_poll_timeout.3 |  26 ++
 src/include/liburing.h                        |   6 +
 src/include/liburing/io_uring.h               |   4 +
 src/liburing.map                              |   7 +
 src/register.c                                |  23 +
 12 files changed, 955 insertions(+)
 create mode 100644 examples/napi-busy-poll-client.c
 create mode 100644 examples/napi-busy-poll-server.c
 create mode 100644 man/io_uring_register_napi_busy_poll_timeout.3
 create mode 100644 man/io_uring_register_napi_prefer_busy_poll.3
 create mode 100644 man/io_uring_unregister_napi_busy_poll_timeout.3


base-commit: 8fc22e3b3348c0a6384ec926e0b19b6707622e58
-- 
2.30.2