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| kwin_overlay_subsurface:worklist [2026/05/02 17:51] – Phase 1 deliverables — initial upload from kwin_overlay_subsurface dossier markus_fritsche | kwin_overlay_subsurface:worklist [2026/05/02 20:16] (current) – Phase 3 — pass-1 LOCKED status note added under the Phase 3 heading markus_fritsche |
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| ===== Phase 1 — leading research question ===== | ===== Phase 1 — leading research question ===== |
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| | **Status: LOCKED 2026-05-02.** Answer in [[kwin_overlay_subsurface:phase2_source_findings|phase2_source_findings]] lead section. Outcome: NO on both promotion paths for windowed Brave on rockchip-drm — Phase 4 design space narrows to architect's hypothesis (a), dmabuf-to-GL-texture import-caching. |
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| **On what condition does KWin promote a ''wp_linux_dmabuf_v1'' surface to direct scanout versus falling back to GPU composite, and does the hantro NV12 ''DRM_FORMAT_MOD_LINEAR'' output satisfy those conditions on this DRM driver (rockchip-drm on RK3568, Mesa 26.0.5)?** | **On what condition does KWin promote a ''wp_linux_dmabuf_v1'' surface to direct scanout versus falling back to GPU composite, and does the hantro NV12 ''DRM_FORMAT_MOD_LINEAR'' output satisfy those conditions on this DRM driver (rockchip-drm on RK3568, Mesa 26.0.5)?** |
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| ===== Phase 3 — measurement (validate hypotheses with hot-path data) ===== | ===== Phase 3 — measurement (validate hypotheses with hot-path data) ===== |
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| | **Status: pass-1 LOCKED 2026-05-02.** H1 rejected at N=1 across C0/C1/C2 + exploratory C3 stock-Brave. Verdict and full data in [[kwin_overlay_subsurface:phase3_findings|phase3_findings]]. Pass-2 replicates deferred — replication does not change a verdict reached two orders of magnitude beyond the threshold. Phase 4 design space pivots to H1' (Wayland-protocol dispatch as the kwin CPU cost) and to a new H1''-drops question (drops are not CPU-caused, per the Brave-vs-chromium-fourier inversion). Phase 2-prime source-read of ''KWin::Display::dispatchEvents'' and the libwayland-server arrival path becomes the new Phase 4 prerequisite. |
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| * [ ] **Highest-value first measurement**: ''perf record -p $(pgrep kwin_wayland)'' during BOTH cage and direct-Brave runs. Same clip, same 70 s window. Convert hypothesis from Phase 2 into hot-path evidence. Architect: "single highest-value remaining measurement, and it's cheap." | * [ ] **Highest-value first measurement**: ''perf record -p $(pgrep kwin_wayland)'' during BOTH cage and direct-Brave runs. Same clip, same 70 s window. Convert hypothesis from Phase 2 into hot-path evidence. Architect: "single highest-value remaining measurement, and it's cheap." |
