lightway-app-utils: iouring: Make sqpoll idle time configurable

[xv-ian-c]

Description

Make it configurable and plumb it all the way through to the config file. The default remains 100ms.

Motivation and Context

This is a useful tunable to play with when trading CPU use vs performance.

How Has This Been Tested?

Observing the behaviour using htop and in particular observing that with it set to 0 no kernel thread is created.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• The correct base branch is being used, if not main

[github-actions]

Code coverage summary for 2755fac:

Filename                                                     Regions    Missed Regions     Cover   Functions  Missed Functions  Executed       Lines      Missed Lines     Cover    Branches   Missed Branches     Cover
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
lightway-app-utils/src/args/cipher.rs                              7                 7     0.00%           2                 2     0.00%           6                 6     0.00%           0                 0         -
lightway-app-utils/src/args/connection_type.rs                     7                 7     0.00%           2                 2     0.00%           6                 6     0.00%           0                 0         -
lightway-app-utils/src/args/duration.rs                           10                10     0.00%           7                 7     0.00%          15                15     0.00%           0                 0         -
lightway-app-utils/src/args/ip_map.rs                             11                11     0.00%           3                 3     0.00%          15                15     0.00%           0                 0         -
lightway-app-utils/src/args/logging.rs                            20                20     0.00%           4                 4     0.00%          18                18     0.00%           0                 0         -
lightway-app-utils/src/connection_ticker.rs                       44                 4    90.91%          17                 2    88.24%         156                 5    96.79%           0                 0         -
lightway-app-utils/src/dplpmtud_timer.rs                          70                 7    90.00%          22                 4    81.82%         282                11    96.10%           0                 0         -
lightway-app-utils/src/event_stream.rs                             6                 0   100.00%           3                 0   100.00%          13                 0   100.00%           0                 0         -
lightway-app-utils/src/iouring.rs                                170               149    12.35%          26                17    34.62%         328               300     8.54%           0                 0         -
lightway-app-utils/src/metrics.rs                                 18                18     0.00%          18                18     0.00%          36                36     0.00%           0                 0         -
lightway-app-utils/src/sockopt/ip_mtu_discover.rs                 23                23     0.00%           4                 4     0.00%          93                93     0.00%           0                 0         -
lightway-app-utils/src/sockopt/ip_pktinfo.rs                       4                 4     0.00%           1                 1     0.00%          16                16     0.00%           0                 0         -
lightway-app-utils/src/tun.rs                                     82                82     0.00%          22                22     0.00%          94                94     0.00%           0                 0         -
lightway-app-utils/src/utils.rs                                   13                13     0.00%           1                 1     0.00%          11                11     0.00%           0                 0         -
lightway-client/src/args.rs                                       35                35     0.00%          29                29     0.00%          36                36     0.00%           0                 0         -
lightway-client/src/io/inside/tun.rs                              42                42     0.00%           7                 7     0.00%          48                48     0.00%           0                 0         -
lightway-client/src/io/outside/tcp.rs                             50                50     0.00%          10                10     0.00%          45                45     0.00%           0                 0         -
lightway-client/src/io/outside/udp.rs                             63                63     0.00%          12                12     0.00%          61                61     0.00%           0                 0         -
lightway-client/src/keepalive.rs                                 277                49    82.31%          56                 8    85.71%         372                26    93.01%           0                 0         -
lightway-client/src/lib.rs                                       188               188     0.00%          20                20     0.00%         273               273     0.00%           0                 0         -
lightway-client/src/main.rs                                       49                49     0.00%           7                 7     0.00%         166               166     0.00%           0                 0         -
lightway-core/src/borrowed_bytesmut.rs                            87                 1    98.85%          24                 0   100.00%         196                 1    99.49%           0                 0         -
lightway-core/src/builder_predicates.rs                           20                10    50.00%           4                 2    50.00%          32                16    50.00%           0                 0         -
lightway-core/src/cipher.rs                                       10                 0   100.00%           4                 0   100.00%          14                 0   100.00%           0                 0         -
lightway-core/src/connection.rs                                  481               233    51.56%          48                19    60.42%         660               278    57.88%           0                 0         -
lightway-core/src/connection/builders.rs                          63                23    63.49%          18                 7    61.11%         223                54    75.78%           0                 0         -
lightway-core/src/connection/dplpmtud.rs                         767                90    88.27%          69                 1    98.55%         950                11    98.84%           0                 0         -
lightway-core/src/connection/fragment_map.rs                     139                11    92.09%          29                 0   100.00%         292                 7    97.60%           0                 0         -
lightway-core/src/connection/io_adapter.rs                       149                17    88.59%          42                 5    88.10%         319                23    92.79%           0                 0         -
lightway-core/src/connection/key_update.rs                        23                 7    69.57%           5                 0   100.00%          38                19    50.00%           0                 0         -
lightway-core/src/context.rs                                      93                25    73.12%          26                 7    73.08%         199                40    79.90%           0                 0         -
lightway-core/src/context/ip_pool.rs                               7                 3    57.14%           1                 0   100.00%           6                 0   100.00%           0                 0         -
lightway-core/src/context/server_auth.rs                          14                11    21.43%           4                 3    25.00%          24                20    16.67%           0                 0         -
lightway-core/src/io.rs                                            3                 3     0.00%           3                 3     0.00%          10                10     0.00%           0                 0         -
lightway-core/src/lib.rs                                           9                 6    33.33%           4                 1    75.00%          18                 9    50.00%           0                 0         -
lightway-core/src/metrics.rs                                       9                 9     0.00%           7                 7     0.00%          17                17     0.00%           0                 0         -
lightway-core/src/packet.rs                                       27                 7    74.07%           4                 1    75.00%          30                 6    80.00%           0                 0         -
lightway-core/src/plugin.rs                                       70                 8    88.57%          25                 5    80.00%         162                 9    94.44%           0                 0         -
lightway-core/src/utils.rs                                       111                19    82.88%          26                 0   100.00%         184                11    94.02%           0                 0         -
lightway-core/src/version.rs                                      49                 0   100.00%          24                 0   100.00%          94                 0   100.00%           0                 0         -
lightway-core/src/wire.rs                                        154                19    87.66%          39                 0   100.00%         263                 2    99.24%           0                 0         -
lightway-core/src/wire/auth_failure.rs                             9                 1    88.89%           3                 0   100.00%          19                 0   100.00%           0                 0         -
lightway-core/src/wire/auth_request.rs                           152                12    92.11%          37                 0   100.00%         290                 0   100.00%           0                 0         -
lightway-core/src/wire/auth_success_with_config_ipv4.rs           69                 4    94.20%          13                 0   100.00%         145                 0   100.00%           0                 0         -
lightway-core/src/wire/data.rs                                    21                 1    95.24%           7                 0   100.00%          43                 0   100.00%           0                 0         -
lightway-core/src/wire/data_frag.rs                               47                 1    97.87%          19                 0   100.00%          94                 0   100.00%           0                 0         -
lightway-core/src/wire/ping.rs                                    24                 3    87.50%           8                 0   100.00%          69                 0   100.00%           0                 0         -
lightway-core/src/wire/pong.rs                                    15                 2    86.67%           5                 0   100.00%          34                 0   100.00%           0                 0         -
lightway-core/src/wire/server_config.rs                           20                 2    90.00%           5                 0   100.00%          44                 0   100.00%           0                 0         -
lightway-server/src/args.rs                                       30                30     0.00%          28                28     0.00%          28                28     0.00%           0                 0         -
lightway-server/src/auth.rs                                      109                36    66.97%          21                 5    76.19%         150                28    81.33%           0                 0         -
lightway-server/src/connection.rs                                 50                50     0.00%          23                23     0.00%         107               107     0.00%           0                 0         -
lightway-server/src/connection_manager.rs                        105               105     0.00%          34                34     0.00%         217               217     0.00%           0                 0         -
lightway-server/src/connection_manager/connection_map.rs          90                 9    90.00%          27                 2    92.59%         274                 9    96.72%           0                 0         -
lightway-server/src/io/inside/tun.rs                              28                28     0.00%           8                 8     0.00%          34                34     0.00%           0                 0         -
lightway-server/src/io/outside/tcp.rs                             78                78     0.00%          10                10     0.00%          85                85     0.00%           0                 0         -
lightway-server/src/io/outside/udp.rs                            136               136     0.00%          18                18     0.00%         247               247     0.00%           0                 0         -
lightway-server/src/io/outside/udp/cmsg.rs                        47                16    65.96%          14                 5    64.29%         233                56    75.97%           0                 0         -
lightway-server/src/ip_manager.rs                                 82                25    69.51%          19                 4    78.95%         254                28    88.98%           0                 0         -
lightway-server/src/ip_manager/ip_pool.rs                        101                 1    99.01%          32                 0   100.00%         305                 0   100.00%           0                 0         -
lightway-server/src/lib.rs                                        94                94     0.00%          11                11     0.00%         143               143     0.00%           0                 0         -
lightway-server/src/main.rs                                       67                67     0.00%           9                 9     0.00%         171               171     0.00%           0                 0         -
lightway-server/src/metrics.rs                                    84                82     2.38%          75                73     2.67%         193               189     2.07%           0                 0         -
lightway-server/src/statistics.rs                                 56                24    57.14%           9                 4    55.56%         104                42    59.62%           0                 0         -
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
TOTAL                                                           4988              2140    57.10%        1114               475    57.36%        9104              3198    64.87%           0                 0         -

✅ Region coverage 57% passes
✅ Line coverage 64% passes

[kp-mariappan-ramasamy]

Think it is better if we should do a sanity check for this value for upper bound like 1 or 2 seconds.
Setting this as large value will make CPU run 100% for longer time.

What do you think ?

[xv-ian-c]

I think sysadmins need to understand the consequences of fiddling with these kinds of low level tunables.

[kp-mariappan-ramasamy]

LGTM except boundary check