feat(prof) I/O profiling preview

[realFlowControl]

Description

This adds I/O profiling preview to the PHP profiler on Linux machines (it is only compiled for Linux, but technically this is a ELF64 feature and could work on other OS that are using ELF64 too):

• adds DD_PROFILING_IO_ENABLED / datadog.profiling.io_enabled configuration (default false)
• adds new sample types:
  • socket_read_time
  • socket_write_time
  • file_read_time
  • file_write_time
  • socket_read_size
  • socket_write_size
  • file_read_size
  • file_write_size

Known limitations:

• tests, including correctness are missing
• benchmarks are missing
• GOT hooking code and I/O profiling code is mixed
• mmap() is not observed
• SQLite is not observed (probably due to missing mmap() support)

Those things will be added/handled in future PRs, also because this feature is still experimental. The sampling distances are best guess and will likely be adjusted later.

https://datadoghq.atlassian.net/browse/PROF-11288

Reviewer checklist

• Test coverage seems ok.
• Appropriate labels assigned.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 74.74%. Comparing base (f6a7e40) to head (016d5c8).

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #3083      +/-   ##
============================================
+ Coverage     72.95%   74.74%   +1.79%     
  Complexity     2790     2790              
============================================
  Files           139      112      -27     
  Lines         15280    11042    -4238     
  Branches       1047        0    -1047     
============================================
- Hits          11147     8253    -2894     
+ Misses         3580     2789     -791     
+ Partials        553        0     -553     

Flag	Coverage Δ
appsec-extension	?
tracer-php	74.74% <ø> (ø)

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see 27 files with indirect coverage changes

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[pr-commenter]

Benchmarks [ profiler ]

Benchmark execution time: 2025-02-14 10:52:33

Comparing candidate commit 016d5c8 in PR branch florian/poc-got-io-profiling with baseline commit f6a7e40 in branch master.

Found 1 performance improvements and 0 performance regressions! Performance is the same for 30 metrics, 5 unstable metrics.

scenario:walk_stack/1

• 🟩 wall_time [-289.108ns; -285.495ns] or [-2.341%; -2.312%]