[PATCH v6 0/4] liburing: add api for napi busy poll

[Stefan Roesch <shr@devkernel.io>]

This adds two new api's to set/clear the napi busy poll settings. The two
new functions are called:
- io_uring_register_napi
- io_uring_unregister_napi

The patch series also contains the documentation for the two 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:
- V6:
  - Check return value of unregister napi call and verify that busy poll
    timeout and prefer busy poll return the expected values.
- V5:
  - Fixes to documentation.
  - Correct opcode for unregister call
  - Initialize napi structure in example programs
  - Address tab issues in recordRTT()
- V4:
  - Modify functions to use a structure to pass the napi busy poll settings
    to the kernel.
  - Return previous values when returning from the above functions.
  - Rename the functions and remove one function (no longer needed as the
    data is passed as a structure)
- 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



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

 .gitignore                       |   2 +
 CHANGELOG                        |   1 +
 examples/Makefile                |   2 +
 examples/napi-busy-poll-client.c | 451 +++++++++++++++++++++++++++++++
 examples/napi-busy-poll-server.c | 386 ++++++++++++++++++++++++++
 man/io_uring_register_napi.3     |  40 +++
 man/io_uring_unregister_napi.3   |  27 ++
 src/include/liburing.h           |   3 +
 src/include/liburing/io_uring.h  |  12 +
 src/liburing.map                 |   3 +
 src/register.c                   |  12 +
 11 files changed, 939 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.3
 create mode 100644 man/io_uring_unregister_napi.3


base-commit: d32d53b65377d846635387ce6c1cd2ed0d700f92
-- 
2.30.2