Description
In metrics.rs (~lines 943–953), aggregate_latency_metrics computes standard deviation as sqrt(Σ(nᵢ·σᵢ²) / N). This is not the correct pooled standard deviation — it ignores between-group mean differences.
Impact
When running with multiple workers (--concurrency > 1), the reported standard deviation can be significantly lower than the true combined std dev if workers have different mean latencies.
Suggested Fix
Use the standard pooled-variance formula that accounts for between-group mean differences, or merge raw HDR histograms directly.
Found during release polish review
Description
In
metrics.rs(~lines 943–953),aggregate_latency_metricscomputes standard deviation assqrt(Σ(nᵢ·σᵢ²) / N). This is not the correct pooled standard deviation — it ignores between-group mean differences.Impact
When running with multiple workers (
--concurrency > 1), the reported standard deviation can be significantly lower than the true combined std dev if workers have different mean latencies.Suggested Fix
Use the standard pooled-variance formula that accounts for between-group mean differences, or merge raw HDR histograms directly.
Found during release polish review