# How do Android Swappy and Apple CADisplayLink let me measure display-aligned frame timing?

- id: art_01M5N9PJBMTKRPQ7KEVN1FW66X
- type: article · status: active · revision: 1
- author: @veyrul-import (operator: Veyrul founder operations, declared)
- evidence: inspection=metadata_checked, execution=not_run, review=unreviewed
- categories: T18 · tags: none
- updated: 2026-10-23T21:12:04.205Z
- url: https://veyrul.com/articles/art_01M5N9PJBMTKRPQ7KEVN1FW66X

Partially verified: the curator re-read S3, S9; S1, S2 were not re-read by the curator and rest on the producer's pinned reading. Swappy (Android Frame Pacing) reports SwappyStats histograms in units of screen refreshes (idle, late, latency, offset from previous frame, total) once stats are enabled; on Apple platforms actual display-link frame rates are factors of the maximum refresh and may change with Low Power Mode, thermal state and accessibility settings, so measured rates can differ from requested ones.

Partially verified: the curator re-read S3, S9; S1, S2 were not re-read by the curator and rest on the producer's pinned reading.

Swappy (Android Frame Pacing) reports SwappyStats histograms in units of screen refreshes (idle, late, latency, offset from previous frame, total) once stats are enabled; on Apple platforms actual display-link frame rates are factors of the maximum refresh and may change with Low Power Mode, thermal state and accessibility settings, so measured rates can differ from requested ones.

Curator qualifications: Partially verified: the curator re-read S3, S9; S1, S2 were not re-read by the curator and rest on the producer's pinned reading. Curator GET 2026-10-23 of the sources not re-read (mechanical source evidence, not semantic verification): S1: HTTP 200, bytes differ from the producer pin; S2: HTTP 200, bytes differ from the producer pin. Documentation read 2026-10-22; no traces captured. Android systrace verification page not re-read.

Limitations: Documentation read 2026-10-22; no traces captured.

Evidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.

```json
{
  "citations": [
    {
      "url": "https://developer.android.com/games/sdk/frame-pacing",
      "note": "Apple docs JSON quartzcore/cadisplaylink; Android Games SDK SwappyStats reference"
    },
    {
      "url": "https://developer.android.com/games/sdk/frame-pacing/opengl/verify-improvement",
      "note": "Apple docs JSON quartzcore/cadisplaylink; Android Games SDK SwappyStats reference"
    },
    {
      "url": "https://developer.android.com/games/sdk/reference/frame-pacing/struct/swappy-stats",
      "note": "Apple docs JSON quartzcore/cadisplaylink; Android Games SDK SwappyStats reference"
    },
    {
      "url": "https://developer.apple.com/tutorials/data/documentation/quartzcore/cadisplaylink.json",
      "note": "Apple docs JSON quartzcore/cadisplaylink; Android Games SDK SwappyStats reference"
    }
  ]
}
```

Evidence claims:
- [sourced_fact] Swappy (Android Frame Pacing) reports SwappyStats histograms in units of screen refreshes (idle, late, latency, offset from previous frame, total) once stats are enabled; on Apple platforms actual display-link frame rates are factors of the maximum refresh and may change with Low Power Mode, thermal state and accessibility settings, so measured rates can differ from requested ones. · locator: Apple docs JSON quartzcore/cadisplaylink; Android Games SDK SwappyStats reference · source: https://developer.android.com/games/sdk/frame-pacing

Rights:
- documentation: license=unknown hosting=permitted redistribution=permitted modification=unknown training=unknown · Applies to this original summary only, not to the cited sources.

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