====== kwin_overlay_subsurface — KWin per-frame compositor cost on parent + wp_subsurface ======

A scope-narrow campaign to identify and remove the per-frame cost in KWin's overlay-subsurface composite path on Mali-G52 / panfrost / KDE Plasma 6.6.4 Wayland (PineTab2, RK3568). Spun off from [[ohm_gl_fix:start|ohm_gl_fix]] on 2026-05-02 after Phase 3 re-measurement isolated KWin specifically as the residual drop source on the in-scope use case (Brave/Chromium 1080p30 H.264).

  * Local dossier: ''~/src/kwin_overlay_subsurface/'' on boltzmann (canonical scope + reference list)
  * Reference target: **ohm** — PineTab2, Rockchip RK3568 (4× Cortex-A55, Mali-G52 MP2, hantro G1/G2 VPU). Kernel ''6.19.10-danctnix1-1-pinetab2''. Mesa 26.0.5. KDE Plasma 6.6.4 Wayland.

===== Status — Phase 1 locked 2026-05-02 =====

  * [[kwin_overlay_subsurface:readme|README — campaign overview]] — scope, hardware target, sources of truth, pre-MR checklist, non-upstreaming default.
  * [[kwin_overlay_subsurface:worklist|Worklist — phase plan with leading question]] — Phase 1 leading research question, Phase 2 source-archaeology reading list, Phases 3-8 outline.
  * [[kwin_overlay_subsurface:phase0_findings|Phase 0 findings — handover from ohm_gl_fix]] — decisive cage vs KWin A/B, what's ruled out, A2 trajectory pattern, software stack at handover.
  * [[kwin_overlay_subsurface:phase1_lock|Phase 1 lock — locked metric cells]] — one-line goal, four binding cells, reference floor, measurement protocol.
  * [[kwin_overlay_subsurface:phase2_source_findings|Phase 2 source archaeology — Phase 1 leading question answer + Phase 2 stub]] — **the new artefact**. Short answer NO; Phase 4 design space narrows to the import-caching hypothesis only.
  * [[kwin_overlay_subsurface:phase3_protocol|Phase 3 measurement protocol — pre-registered hypothesis, falsification table, orchestration handshake]] — **the new artefact**. 9-run perf-record campaign locked 2026-05-02; H1: ''glEGLImageTargetTexture2DOES'' ≥ 20 % of ''kwin_wayland'' self-time in C1, ≥ 10 pp above cage.
  * [[kwin_overlay_subsurface:phase3_findings|Phase 3 measurement findings — pass-1 LOCKED, H1 rejected, H1' emerges]] — **the new artefact**. Pass-1 verdict 2026-05-02: target symbol peaks at 0.15 % vs the 20 % threshold; per-frame Wayland-protocol dispatch dominates instead; Brave-vs-chromium-fourier inversion shows drops are not CPU-caused.
  * [[kwin_overlay_subsurface:metrics|metrics.csv — locked Phase 1 cells]] — schema + locked rows; raw CSV as attachment.
  * [[kwin_overlay_subsurface:ohm_tooling_revert_log|ohm tooling revert log]] — every package / one-off installed on ohm during the campaign, for Phase 8 close-out.

===== Phase 1 evidence (raw attachments) =====

  * [[kwin_overlay_subsurface:evidence:ohm_drm_info_2026-05-02|ohm_drm_info_2026-05-02.json (inlined)]] — full ''drm_info'' JSON dump from ohm (rockchip-drm plane format/modifier blob + connector/CRTC enumeration).
  * [[kwin_overlay_subsurface:evidence:ohm_modetest_planes_2026-05-02|ohm_modetest_planes_2026-05-02.txt (inlined)]] — ''modetest -p'' plane output on ohm, used to cross-check the JSON.
  * [[kwin_overlay_subsurface:evidence:metrics_csv|metrics.csv (inlined)]] — raw CSV of locked binding cells.

===== Sibling =====

  * [[ohm_gl_fix:start|ohm_gl_fix]] — Mali-G52 EGL/dmabuf import efficiency campaign. Closed 2026-05-02 with the explicit re-scope into this campaign. Phase 0 of this campaign inherits its evidence, A2 trajectory, decisive A/B, and software stack.

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//Namespace landing created 2026-05-02 alongside the Phase 1 leading-question lock (commit ''595a130'' on master in the local dossier).//