Files
ComfyUI_frontend/scripts/perf-stats.ts
Christian Byrne 7b316eb9a2 feat: add statistical significance to perf report with z-score thresholds (#9305)
## Summary

Replace fixed 10%/20% perf delta thresholds with dynamic σ-based
classification using z-scores, eliminating false alarms from naturally
noisy duration metrics (10-17% CV).

## Changes

- **What**:
- Run each perf test 3× (`--repeat-each=3`) and report the mean,
reducing single-run noise
- Download last 5 successful main branch perf artifacts to compute
historical μ/σ per metric
- Replace fixed threshold flags with z-score significance: `⚠️
regression` (z>2), ` neutral/improvement`, `🔇 noisy` (CV>50%)
  - Add collapsible historical variance table (μ, σ, CV) to PR comment
- Graceful cold start: falls back to simple delta table until ≥2
historical runs exist
- New `scripts/perf-stats.ts` module with `computeStats`, `zScore`,
`classifyChange`
  - 18 unit tests for stats functions

- **CI time impact**: ~3 min → ~5-6 min (repeat-each adds ~2 min,
historical download <10s)

## Review Focus

- The `gh api` call in the new "Download historical perf baselines"
step: it queries the last 5 successful push runs on the base branch. The
`gh` CLI is available natively on `ubuntu-latest` runners and
auto-authenticates with `GITHUB_TOKEN`.
- `getHistoricalStats` averages per-run measurements before computing
cross-run σ — this is intentional since historical artifacts may also
contain repeated measurements after this change lands.
- The `noisy` classification (CV>50%) suppresses metrics like `layouts`
that hover near 0 and have meaningless percentage swings.

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-9305-feat-add-statistical-significance-to-perf-report-with-z-score-thresholds-3156d73d3650818d9360eeafd9ae7dc1)
by [Unito](https://www.unito.io)
2026-03-04 16:16:53 -08:00

64 lines
1.5 KiB
TypeScript

export interface MetricStats {
mean: number
stddev: number
min: number
max: number
n: number
}
export function computeStats(values: number[]): MetricStats {
const n = values.length
if (n === 0) return { mean: 0, stddev: 0, min: 0, max: 0, n: 0 }
if (n === 1)
return { mean: values[0], stddev: 0, min: values[0], max: values[0], n: 1 }
const mean = values.reduce((a, b) => a + b, 0) / n
const variance = values.reduce((sum, v) => sum + (v - mean) ** 2, 0) / (n - 1)
return {
mean,
stddev: Math.sqrt(variance),
min: Math.min(...values),
max: Math.max(...values),
n
}
}
export function zScore(value: number, stats: MetricStats): number | null {
if (stats.stddev === 0 || stats.n < 2) return null
return (value - stats.mean) / stats.stddev
}
export type Significance = 'regression' | 'improvement' | 'neutral' | 'noisy'
export function classifyChange(
z: number | null,
historicalCV: number
): Significance {
if (historicalCV > 50) return 'noisy'
if (z === null) return 'neutral'
if (z > 2) return 'regression'
if (z < -2) return 'improvement'
return 'neutral'
}
export function formatSignificance(
sig: Significance,
z: number | null
): string {
switch (sig) {
case 'regression':
return `⚠️ z=${z!.toFixed(1)}`
case 'improvement':
return `z=${z!.toFixed(1)}`
case 'noisy':
return 'variance too high'
case 'neutral':
return z !== null ? `z=${z.toFixed(1)}` : '—'
}
}
export function isNoteworthy(sig: Significance): boolean {
return sig === 'regression'
}