Cycle 4 (LPF wd=8) closure: M1=100%, R=0.34, M4=+4.1%, PASS
Fourth daedalus-fourier kernel — VP9 8-tap inner loop filter wd=8
h_8_8 variant. Width extension of cycle 2's wd=4; completes VP9
inner-edge LPF coverage. Full cycle Phase 1-7 + M4'''' in one
combined go (cycle compressed since incremental from cycle 2).
Phase 5 review explicitly skipped (incremental ~30-line shader
delta from cycle 2 + same geometry + cycle-2 RED-pattern checks
still apply). Flagged in docs/k4_lpf8_phase4_7.md per dev_process.md
"Skipping phases is a deliberate choice that should be flagged."
Phase 6 v1 first-light: M1'''' 100.0000% bit-exact (65536/65536)
first try. Shaderdb shows 231 inst, 4 hardware threads, 0 spills,
27 max-temps, 48 uniforms — compiler at the latency-hiding ceiling.
Performance:
M3'''' NEON (single-core) 52.382 Medge/s
M2'''' QPU isolation 17.847 Medge/s
R'''' 0.341 → ORANGE band
30fps floor margin 9.2x (isolation), 20.3x (mixed)
M4'''' concurrent matrix:
NEON 4-core 37.823 Medge/s <- baseline
QPU only 14.867 Medge/s
MIXED NEON-3 + QPU 39.389 Medge/s <- +4.1% PASS
Verdict: YELLOW-via-M4'''' PASS. Deploy wd=8 LPF on QPU alongside
cycle 2 wd=4. Combined VP9 inner-edge LPF coverage now complete.
Cross-cycle LPF comparison:
| | wd=4 (k2) | wd=8 (k4) |
| M3 NEON | 48.3 | 52.4 |
| M2 QPU iso | 19.6 | 17.8 |
| R iso | 0.41 | 0.34 |
| M4 delta | +6.9% | +4.1% |
| 30fps mixed | 7.2x | 20.3x |
| Verdict | GO QPU | GO QPU |
NEW finding (Phase 9 lesson): NEON gets faster per edge as filter
width grows (20.7 → 19.1 ns wd=4 → wd=8). The relative QPU loss
grows with width. wd=16 would probably flip negative based on the
trend line.
Deployment recipe with cycle 4:
IDCT 8x8 (k1) -> QPU (R=0.92, +7% mixed)
LPF wd=4 (k2) -> QPU (R=0.41, +7% mixed)
LPF wd=8 (k4) -> QPU (R=0.34, +4% mixed)
MC 8h (k3) -> CPU (R=0.067, -19% mixed)
Entropy -> CPU (structural)
VP9 inner-edge LPF coverage complete. Project continues to higgs
deployment plumbing or further kernels per user direction.
New artifacts:
- src/v3d_lpf_h_8_8.comp — GLSL shader
- tests/vp9_lpf8_ref.c — standalone C ref
- tests/bench_neon_lpf8.c — M1+M3 bench
- tests/bench_v3d_lpf8.c — M1+M2 bench
- tests/bench_concurrent_lpf8.c — M4 pthread bench
- docs/k4_lpf8_phase1_3.md + phase4_7.md — combined cycle docs
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
marfrit
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