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--- kwin_overlay_subsurface:phase2_source_findings [2026/05/02 18:55] – Phase 1 lock note + Phase 2 architectural map, file-level findings, hypothesis (concrete file:line) markus_fritsche
+++ kwin_overlay_subsurface:phase2_source_findings [2026/05/02 20:16] (current) – SUPERSEDED block-quote at top of Phase 2 hypothesis section, pointing at phase3_findings (prior preserved verbatim) markus_fritsche
@@ Line 214: / Line 214: @@
 ===== Phase 2 hypothesis — concrete, file:line =====
+> **SUPERSEDED 2026-05-02 by Phase 3 measurement.** Verdict: H1 rejected at N=1 across C0/C1/C2 + exploratory C3 stock-Brave. The symbol's self-time peaks at 0.15 % vs the 20 % threshold. See [[kwin_overlay_subsurface:phase3_findings|phase3_findings]]. The hypothesis text below is preserved as the "what we believed before measurement" record per the discipline rule (''feedback_phase_discipline.md''); do not edit it. New working hypothesis H1' (per-frame Wayland-protocol dispatch dominates) emerges from Phase 3 and gets its own Phase 2-prime source-read.
 **Per-frame cost in KWin's parent + wp_subsurface composite path on Mali-G52 panfrost lives in ''OpenGLSurfaceTexture::updateDmabufTexture'' (''src/scene/surfaceitem.cpp:472-501''), specifically the ''glEGLImageTargetTexture2DOES'' call at line 490 (multi-plane YUV) / line 496 (single-plane).**