ci: check benchmark timings only without coverage

[haakon-e]

Purpose

Make the timing checks in test/performance_tests.jl measure the code instead of the coverage instrumentation. They fail on every Julia 1.12 job since #811, although the code runs well within its budgets.

Content

The ci jobs ran the tests with coverage. On Julia 1.12, coverage slows the 1M bulk tendencies about 20-fold, so the timing budgets failed:

LinearizedAverage, Float64	Julia 1.10	Julia 1.12
without coverage	0.43 μs	0.41 μs
with coverage	3.1 μs	8.9 μs (budget 5.5 μs)
with coverage, 3 substeps	9.3 μs	26.4 μs (budget 18 μs)

Measured locally on main (Apple M-series); the coverage numbers on 1.12 match those in the CI logs of #811, #797 and #801.

• The ci jobs now run without coverage, so their benchmarks time the code itself. Coverage comes from the CodeCov workflow alone, which already runs the test suite with coverage on every pull request and uploads it.
• bench_press skips the timing check when coverage is on and keeps the allocation checks. Without this, a timing failure in the CodeCov job would fail the job and skip its coverage upload.

Locally on Julia 1.12, all 536 performance checks pass without coverage. With coverage, the 134 timing checks are reported as broken and the 402 others pass.

Codecov now receives one upload per push, from Julia 1.11 on Ubuntu, instead of seven, so lines that run only on another Julia version or operating system no longer count as covered.

This supersedes #760.

Breaking changes

None.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.93%. Comparing base (78764ba) to head (c939312).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #816      +/-   ##
==========================================
+ Coverage   93.62%   93.93%   +0.31%     
==========================================
  Files          59       55       -4     
  Lines        3201     3102      -99     
==========================================
- Hits         2997     2914      -83     
+ Misses        204      188      -16     

Components	Coverage Δ
src	93.93% <ø> (-0.43%)	⬇️
ext	∅ <ø> (∅)

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[imreddyTeja]

This pattern is nice. I didn't realize codecov slowed down execution that much! Is the slowdown only that extreme when using Julia 1.12?

[haakon-e]

This pattern is nice. I didn't realize codecov slowed down execution that much! Is the slowdown only that extreme when using Julia 1.12?

Good question. I only tried 1.10 and 1.12 because that's what our CI runs. There is still a ~7x slowdown on 1.10, compared to ~21x slowdown on 1.12. Not sure how much run-to-run variance there is.