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smoke scenarios for targeted and conservative 16/16 impact selection
Follow-up
Consume the generated matrix with validation jobs by mode (rust-crates, rust-source, native-artifact, native-package, packaging, and contract-tests), starting in report-only mode.
Found 16 performance improvements and 5 performance regressions! Performance is the same for 135 metrics, 0 unstable metrics.
Explanation
This is an A/B test comparing a candidate commit's performance against that of a baseline commit. Performance changes are noted in the tables below as:
🟩 = significantly better candidate vs. baseline
🟥 = significantly worse candidate vs. baseline
We compute a confidence interval (CI) over the relative difference of means between metrics from the candidate and baseline commits, considering the baseline as the reference.
If the CI is entirely outside the configured SIGNIFICANT_IMPACT_THRESHOLD (or the deprecated UNCONFIDENCE_THRESHOLD), the change is considered significant.
Feel free to reach out to #apm-benchmarking-platform on Slack if you have any questions.
More details about the CI and significant changes
You can imagine this CI as a range of values that is likely to contain the true difference of means between the candidate and baseline commits.
CIs of the difference of means are often centered around 0%, because often changes are not that big:
---------------------------------(------|---^--------)-------------------------------->
-0.6% 0% 0.3% +1.2%
| | |
lower bound of the CI --' | |
sample mean (center of the CI) -------------' |
upper bound of the CI ----------------------'
As described above, a change is considered significant if the CI is entirely outside the configured SIGNIFICANT_IMPACT_THRESHOLD (or the deprecated UNCONFIDENCE_THRESHOLD).
For instance, for an execution time metric, this confidence interval indicates a significantly worse performance:
----------------------------------------|---------|---(---------^---------)---------->
0% 1% 1.3% 2.2% 3.1%
| | | |
significant impact threshold --------------' | | |
lower bound of CI --------------' | |
sample mean (center of the CI) --------------------------' |
upper bound of CI ----------------------------------'
scenario:otlp/e2e_json/1x1000
🟥 execution_time [+358.516µs; +363.380µs] or [+8.929%; +9.050%]
scenario:otlp/encode_json/1x1000
🟥 execution_time [+338.561µs; +342.656µs] or [+19.954%; +20.196%]
scenario:otlp/encode_protobuf/1x1000
🟩 execution_time [-97.490µs; -95.328µs] or [-8.476%; -8.288%]
scenario:vec_map/as_deduped_map/already_deduped/8
🟩 execution_time [-0.610ns; -0.603ns] or [-4.212%; -4.158%]
scenario:vec_map/contains_key/128
🟩 execution_time [-1.129µs; -1.117µs] or [-7.167%; -7.091%]
🟩 throughput [+620127.884op/s; +627065.559op/s] or [+7.634%; +7.720%]
scenario:vec_map/contains_key/16
🟩 execution_time [-25.142ns; -24.697ns] or [-9.868%; -9.693%]
🟩 throughput [+6748568.244op/s; +6864316.508op/s] or [+10.746%; +10.931%]
scenario:vec_map/contains_key/64
🟩 execution_time [-341.779ns; -336.286ns] or [-8.116%; -7.986%]
🟩 throughput [+1320159.157op/s; +1341295.089op/s] or [+8.686%; +8.825%]
scenario:vec_map/contains_key/8
🟩 execution_time [-3.729ns; -3.589ns] or [-4.997%; -4.809%]
🟩 throughput [+5424277.211op/s; +5630019.711op/s] or [+5.060%; +5.252%]
scenario:vec_map/get_hit/128
🟩 throughput [+382257.620op/s; +390618.535op/s] or [+4.082%; +4.171%]
scenario:vec_map/get_hit/16
🟩 execution_time [-36.115ns; -35.786ns] or [-15.291%; -15.151%]
🟩 throughput [+12107806.294op/s; +12215721.546op/s] or [+17.873%; +18.033%]
scenario:vec_map/get_hit/8
🟩 execution_time [-11.063ns; -10.993ns] or [-17.016%; -16.910%]
🟩 throughput [+25053710.687op/s; +25225692.001op/s] or [+20.360%; +20.499%]
scenario:vec_map/get_miss/128
🟩 execution_time [-4.124ns; -3.825ns] or [-5.095%; -4.725%]
scenario:vec_map/get_miss/16
🟥 execution_time [+17.943ns; +18.375ns] or [+191.413%; +196.024%]
scenario:vec_map/get_miss/64
🟥 execution_time [+21.883ns; +22.487ns] or [+75.580%; +77.667%]
scenario:vec_map/get_miss/8
🟥 execution_time [+10.917ns; +11.148ns] or [+145.261%; +148.333%]
Benchmark execution time: 2026-09-11 14:08:26
Comparing candidate commit d334a78 in PR branch codex/downstream-impact-mvp-20260909 with baseline commit 132842f in branch main.
Found 3 performance improvements and 23 performance regressions! Performance is the same for 140 metrics, 10 unstable metrics.
Explanation
This is an A/B test comparing a candidate commit's performance against that of a baseline commit. Performance changes are noted in the tables below as:
🟩 = significantly better candidate vs. baseline
🟥 = significantly worse candidate vs. baseline
We compute a confidence interval (CI) over the relative difference of means between metrics from the candidate and baseline commits, considering the baseline as the reference.
If the CI is entirely outside the configured SIGNIFICANT_IMPACT_THRESHOLD (or the deprecated UNCONFIDENCE_THRESHOLD), the change is considered significant.
Feel free to reach out to #apm-benchmarking-platform on Slack if you have any questions.
More details about the CI and significant changes
You can imagine this CI as a range of values that is likely to contain the true difference of means between the candidate and baseline commits.
CIs of the difference of means are often centered around 0%, because often changes are not that big:
---------------------------------(------|---^--------)-------------------------------->
-0.6% 0% 0.3% +1.2%
| | |
lower bound of the CI --' | |
sample mean (center of the CI) -------------' |
upper bound of the CI ----------------------'
As described above, a change is considered significant if the CI is entirely outside the configured SIGNIFICANT_IMPACT_THRESHOLD (or the deprecated UNCONFIDENCE_THRESHOLD).
For instance, for an execution time metric, this confidence interval indicates a significantly worse performance:
----------------------------------------|---------|---(---------^---------)---------->
0% 1% 1.3% 2.2% 3.1%
| | | |
significant impact threshold --------------' | | |
lower bound of CI --------------' | |
sample mean (center of the CI) --------------------------' |
upper bound of CI ----------------------------------'
scenario:alloc_free/system/4096
🟥 execution_time [+12.000ns; +12.152ns] or [+14.628%; +14.814%]
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What does this change?
Adds the first, non-blocking phase of downstream impact analysis for libdatadog pull requests:
This phase intentionally reports potential impact only. It does not claim downstream compatibility yet.
Validation
python3 -m unittest scripts/tests/test_downstream_impact.py(7 tests)Follow-up
Consume the generated matrix with validation jobs by mode (
rust-crates,rust-source,native-artifact,native-package,packaging, andcontract-tests), starting in report-only mode.