[PATCH v3 0/2] selftests: cgroup: improve diagnostics for CPU test failures

[Sebastian Chlad <sebastianchlad@gmail.com>]

Hi,

While running cgroup selftests under CI, the `test_cpu` tests sometimes fail
and it is impossible to tell how significant is the deviation. Often times the failures
are very marginal, but the existing output does not provide enough context to
understand how far the actual values were from the expected ones.

This is an initial idea to get this sorted by adding a new helper: `values_close_report()`,
which prints detailed diagnostic information when two values differ by more than
a given tolerance.

This makes CI logs much more informative in the event of a close
failure without changing normal test behavior.
If the direction is fine, the next steps will be to extend this verbosity to additional
cgroup selftests for easier CI runs and debugging.

Changes since v1:
- Rename values_close_assert() -> values_close_report()
- Remove braces around single-line fprintf()
Changes since v2:
- sorry, I forgot to amend the git commit messages, so corrected here

Thanks,
SebChlad
Sebastian Chlad (2):
  selftests: cgroup: add values_close_report helper
  selftests: cgroup: Use values_close_report in test_cpu

 .../cgroup/lib/include/cgroup_util.h          | 20 +++++++++++++++++++
 tools/testing/selftests/cgroup/test_cpu.c     | 18 ++++++++---------
 2 files changed, 29 insertions(+), 9 deletions(-)

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2.51.0