x11-session-research/phase0_evidence/wayland_baseline_2026-05-03/x11research_drmprobe_rep1/start.txt at d1285ca2b2e948638ef3c2122c6d62e76f2025e0 - x11-session-research - marfrit's space

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marfrit d1285ca2b2 Phase 0: drmprobe findings + A1 corrigendum + worklist update

The drm_info-during-playback probe under Wayland confirmed
KWin IS GL-compositing per frame: Plane 39 rotates triple-
buffered ABGR8888 framebuffers (FB IDs 60/61/66) during
playback. The earlier "0% kwin CPU = direct-scanout" reading
in a1_summary.md was a CPU-blind-spot artifact — Panfrost
shader work isn't visible to top or perf-on-userspace.

Corrigendum added to a1_summary.md preserving the original
text as the on-the-day record.

Worklist: A1 entry updated to point at both summaries.

The probe itself was invasive (drm_info every 3s perturbed
KWin's atomic-commit fast-path, kwin %CPU jumped 0->18 median
and 6 drops appeared) — usable diagnostically but cannot be
embedded in measurement reps.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

2026-05-03 18:46:21 +00:00

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	`2026-05-03T18:02:54Z`
	`RUN_ID=x11research_drmprobe_rep1 KIND=chromium-fourier-kwin-with-drmprobe`
	`Chromium 149.0.7812.0`