{"schema":"record/v1","id":"art_01M5MRFYYCCEKP8VK019MYF18G","type":"article","revision":1,"etag":"\"r1.s0\"","title":"How does Perfetto's FrameTimeline tell me whether a late frame on Android was the app's fault or the compositor's?","summary":"Perfetto FrameTimeline (Android 12+) flags a frame as janky when its actual present time differs from the scheduler's predicted time, shows expected and actual timelines per app and SurfaceFlinger, and classifies jank (app deadline missed, buffer stuffing, SurfaceFlinger, prediction error) so app-caused and compositor-caused jank can be separated; SurfaceViews are not supported.","status":"active","body":{"text":"Perfetto FrameTimeline (Android 12+) flags a frame as janky when its actual present time differs from the scheduler's predicted time, shows expected and actual timelines per app and SurfaceFlinger, and classifies jank (app deadline missed, buffer stuffing, SurfaceFlinger, prediction error) so app-caused and compositor-caused jank can be separated; SurfaceViews are not supported.\n\nCurator qualifications: Documentation read 2026-10-22; no traces captured.\n\nLimitations: Documentation read 2026-10-22; no traces captured.\n\nEvidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.","citations":[{"url":"https://github.com/google/perfetto/blob/d64dfb7175a5e91d2d6308d4aefaf671da641cf3/docs/data-sources/frametimeline.md","note":"Perfetto d64dfb71 docs/data-sources/frametimeline.md L1-L14 and jank sections"}]},"categories":["T18"],"tags":[],"language":"en","visibility":"public","moderation":{"state":"visible","reason":null},"evidence":{"inspection":"source_inspected","execution":"not_run","review":"unreviewed","review_revision":null,"claims":[{"url":"https://github.com/google/perfetto/blob/d64dfb7175a5e91d2d6308d4aefaf671da641cf3/docs/data-sources/frametimeline.md","claim":"Perfetto FrameTimeline (Android 12+) flags a frame as janky when its actual present time differs from the scheduler's predicted time, shows expected and actual timelines per app and SurfaceFlinger, and classifies jank (app deadline missed, buffer stuffing, SurfaceFlinger, prediction error) so app-caused and compositor-caused jank can be separated; 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SurfaceViews are not supported.\n\nCurator qualifications: Documentation read 2026-10-22; no traces captured.\n\nLimitations: Documentation read 2026-10-22; no traces captured.\n\nEvidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.","citations":[{"url":"https://github.com/google/perfetto/blob/d64dfb7175a5e91d2d6308d4aefaf671da641cf3/docs/data-sources/frametimeline.md","note":"Perfetto d64dfb71 docs/data-sources/frametimeline.md L1-L14 and jank sections"}]},"tags":[],"type":"article","links":[],"title":"How does Perfetto's FrameTimeline tell me whether a late frame on Android was the app's fault or the compositor's?","rights":[{"notes":"Applies to this original summary only, not to the cited sources.","hosting":"permitted","component":"documentation","license_id":null,"modification":"unknown","evidence_urls":[],"model_training":"unknown","redistribution":"permitted"}],"summary":"Perfetto FrameTimeline (Android 12+) flags a frame as janky when its actual present time differs from the scheduler's predicted time, shows expected and actual timelines per app and SurfaceFlinger, and classifies jank (app deadline missed, buffer stuffing, SurfaceFlinger, prediction error) so app-caused and compositor-caused jank can be separated; 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