perf: wave 3 follow-up improvements

[Autoparallel]

Summary

• supersedes perf: more improvements #20 with the same follow-up work rebased cleanly onto main
• adds bench_diffgeo coverage to the perf smoke/deep GitHub workflows, including fallback reporting when the baseline branch predates that benchmark target
• specializes DEC curvature traversal for direct SoA/CSR storage
• updates the Wave 3 notes with the continuation profiler pass and rejected experiments

Validation

• cmake --build build -j8
• ctest --test-dir build --output-on-failure -j8
• 14/14 passing locally

Measured Impact

• bench_curvature_kernel/400: 888653 ns -> 816836 ns CPU (-8.08%)
• bench_geometry Grid 1000x1000 curvature: 5.716 ms -> 5.358 ms (-6.26%)
• bench_geometry Grid 1000x1000 structure: 14.516 ms -> 13.661 ms (-5.89%)
• perf CI now reports bench_diffgeo on follow-up branches even when main lacks the target, instead of silently omitting it

Notes

• the continuation profile and rejected experiments are recorded in notes/perf/20260306-wave3/

[github-actions]

Perf Smoke Report

Baseline ref: main
Baseline: e0e8e9f93e5aa434e0ab8e7dde63316c6160b5f9
Backend: parallel
Threads: 4

PR smoke: bench_geometry (baseline e0e8e9f)

• Baseline source: artifacts/perf/base/bench_geometry_base.txt
• Current source: artifacts/perf/head/bench_geometry_head.txt
• Baseline commit: e0e8e9f93e5aa434e0ab8e7dde63316c6160b5f9
• Comparable benchmarks: 16/16
• Improved: 2 | Regressed: 14

Top Wins

Benchmark	Baseline	Current	Delta
bench_geometry_flow_ms/100x100	79.000 us	78.000 us	-1.27%
bench_geometry_flow_ms/250x250	474.000 us	473.000 us	-0.21%

Top Regressions

Benchmark	Baseline	Current	Delta
bench_geometry_structure_ms/100x100	432.000 us	485.000 us	+12.27%
bench_geometry_structure_ms/1000x1000	95.640 ms	106.204 ms	+11.05%
bench_geometry_structure_ms/250x250	5.100 ms	5.522 ms	+8.27%
bench_geometry_frame_ms/1000x1000	214.942 ms	229.595 ms	+6.82%
bench_geometry_structure_ms/500x500	24.228 ms	25.868 ms	+6.77%

Full Comparison

Benchmark	Baseline	Current	Delta	Status
bench_geometry_curvature_ms/1000x1000	109.488 ms	113.456 ms	+3.62%	regressed
bench_geometry_curvature_ms/100x100	1.110 ms	1.140 ms	+2.70%	regressed
bench_geometry_curvature_ms/250x250	6.773 ms	7.085 ms	+4.61%	regressed
bench_geometry_curvature_ms/500x500	27.218 ms	28.838 ms	+5.95%	regressed
bench_geometry_flow_ms/1000x1000	9.814 ms	9.935 ms	+1.23%	regressed
bench_geometry_flow_ms/100x100	79.000 us	78.000 us	-1.27%	improved
bench_geometry_flow_ms/250x250	474.000 us	473.000 us	-0.21%	improved
bench_geometry_flow_ms/500x500	2.445 ms	2.452 ms	+0.29%	regressed
bench_geometry_frame_ms/1000x1000	214.942 ms	229.595 ms	+6.82%	regressed
bench_geometry_frame_ms/100x100	1.621 ms	1.703 ms	+5.06%	regressed
bench_geometry_frame_ms/250x250	12.347 ms	13.080 ms	+5.94%	regressed
bench_geometry_frame_ms/500x500	53.891 ms	57.158 ms	+6.06%	regressed
bench_geometry_structure_ms/1000x1000	95.640 ms	106.204 ms	+11.05%	regressed
bench_geometry_structure_ms/100x100	432.000 us	485.000 us	+12.27%	regressed
bench_geometry_structure_ms/250x250	5.100 ms	5.522 ms	+8.27%	regressed
bench_geometry_structure_ms/500x500	24.228 ms	25.868 ms	+6.77%	regressed

PR smoke: bench_dod (baseline e0e8e9f)

• Baseline source: artifacts/perf/base/bench_dod_base.json
• Current source: artifacts/perf/head/bench_dod_head.json
• Baseline commit: e0e8e9f93e5aa434e0ab8e7dde63316c6160b5f9
• Comparable benchmarks: 11/11
• Improved: 3 | Regressed: 8

Top Wins

Benchmark	Baseline	Current	Delta
bench_curvature_kernel/400	14.887 ms	12.694 ms	-14.73%
bench_curl_energy/2000/16	1.854 ms	1.791 ms	-3.41%
bench_diffusion_build/2000	23.676 ms	23.520 ms	-0.66%

Top Regressions

Benchmark	Baseline	Current	Delta
bench_eigenbasis/2000/16	17.634 ms	18.191 ms	+3.16%
bench_flow_kernel/400	3.168 ms	3.250 ms	+2.57%
bench_markov_step/2000	40.304 us	40.693 us	+0.97%
bench_1form_gram/2000/16	922.350 us	927.913 us	+0.60%
bench_weak_derivative/2000/16	144.261 us	145.113 us	+0.59%

Full Comparison

Benchmark	Baseline	Current	Delta	Status
bench_1form_gram/2000/16	922.350 us	927.913 us	+0.60%	regressed
bench_curl_energy/2000/16	1.854 ms	1.791 ms	-3.41%	improved
bench_curvature_kernel/400	14.887 ms	12.694 ms	-14.73%	improved
bench_diffusion_build/2000	23.676 ms	23.520 ms	-0.66%	improved
bench_eigenbasis/2000/16	17.634 ms	18.191 ms	+3.16%	regressed
bench_flow_kernel/400	3.168 ms	3.250 ms	+2.57%	regressed
bench_hodge_solve/2000/16	146.058 us	146.261 us	+0.14%	regressed
bench_markov_multi_step/2000/20	807.024 us	810.383 us	+0.42%	regressed
bench_markov_multi_step/20000/20	8.631 ms	8.632 ms	+0.01%	regressed
bench_markov_step/2000	40.304 us	40.693 us	+0.97%	regressed
bench_weak_derivative/2000/16	144.261 us	145.113 us	+0.59%	regressed

PR smoke: bench_pipelines (baseline e0e8e9f)

• Baseline source: artifacts/perf/base/bench_pipelines_base.json
• Current source: artifacts/perf/head/bench_pipelines_head.json
• Baseline commit: e0e8e9f93e5aa434e0ab8e7dde63316c6160b5f9
• Comparable benchmarks: 10/10
• Improved: 4 | Regressed: 6

Top Wins

Benchmark	Baseline	Current	Delta
bench_hodge_phase_weak_derivative	5.201 ms	5.047 ms	-2.96%
bench_pipeline_diffusion_main/20	31.800 ms	31.459 ms	-1.07%
bench_pipeline_spectral_main	57.898 ms	57.525 ms	-0.64%
bench_pipeline_diffusion_main/100	35.666 ms	35.656 ms	-0.03%

Top Regressions

Benchmark	Baseline	Current	Delta
bench_hodge_phase_gram	6.458 ms	6.665 ms	+3.21%
bench_hodge_phase_curl_energy	52.176 ms	53.758 ms	+3.03%
bench_hodge_phase_eigenbasis	676.718 ms	689.545 ms	+1.90%
bench_pipeline_hodge_main	820.761 ms	832.987 ms	+1.49%
bench_hodge_phase_circular	12.681 ms	12.770 ms	+0.70%

Full Comparison

Benchmark	Baseline	Current	Delta	Status
bench_hodge_phase_circular	12.681 ms	12.770 ms	+0.70%	regressed
bench_hodge_phase_curl_energy	52.176 ms	53.758 ms	+3.03%	regressed
bench_hodge_phase_eigenbasis	676.718 ms	689.545 ms	+1.90%	regressed
bench_hodge_phase_gram	6.458 ms	6.665 ms	+3.21%	regressed
bench_hodge_phase_solve	5.409 ms	5.409 ms	+0.01%	regressed
bench_hodge_phase_weak_derivative	5.201 ms	5.047 ms	-2.96%	improved
bench_pipeline_diffusion_main/100	35.666 ms	35.656 ms	-0.03%	improved
bench_pipeline_diffusion_main/20	31.800 ms	31.459 ms	-1.07%	improved
bench_pipeline_hodge_main	820.761 ms	832.987 ms	+1.49%	regressed
bench_pipeline_spectral_main	57.898 ms	57.525 ms	-0.64%	improved

PR smoke: bench_diffgeo (baseline e0e8e9f)

• Baseline source: artifacts/perf/base/bench_diffgeo_base.json
• Current source: artifacts/perf/head/bench_diffgeo_head.json
• Baseline commit: e0e8e9f93e5aa434e0ab8e7dde63316c6160b5f9
• Comparable benchmarks: 10/10
• Improved: 1 | Regressed: 9

Top Wins

Benchmark	Baseline	Current	Delta
bench_diffgeo_phase_circular/4000/64/32/32	12.595 ms	12.558 ms	-0.30%

Top Regressions

Benchmark	Baseline	Current	Delta
bench_diffgeo_phase_eigenbasis/1000/50/32/32	53.242 ms	55.938 ms	+5.06%
bench_diffgeo_phase_k2_up/4000/64/32/32	106.383 ms	107.353 ms	+0.91%
bench_diffgeo_phase_eigenbasis/4000/64/32/32	562.468 ms	565.953 ms	+0.62%
bench_diffgeo_phase_circular/1000/50/32/32	3.866 ms	3.889 ms	+0.60%
bench_diffgeo_phase_structure_build/1000/50/32/32	11.868 ms	11.932 ms	+0.54%

Full Comparison

Benchmark	Baseline	Current	Delta	Status
bench_diffgeo_phase_circular/1000/50/32/32	3.866 ms	3.889 ms	+0.60%	regressed
bench_diffgeo_phase_circular/4000/64/32/32	12.595 ms	12.558 ms	-0.30%	improved
bench_diffgeo_phase_eigenbasis/1000/50/32/32	53.242 ms	55.938 ms	+5.06%	regressed
bench_diffgeo_phase_eigenbasis/4000/64/32/32	562.468 ms	565.953 ms	+0.62%	regressed
bench_diffgeo_phase_k1_up/4000/64/32/32	76.475 ms	76.527 ms	+0.07%	regressed
bench_diffgeo_phase_k2_up/4000/64/32/32	106.383 ms	107.353 ms	+0.91%	regressed
bench_diffgeo_phase_structure_build/1000/50/32/32	11.868 ms	11.932 ms	+0.54%	regressed
bench_diffgeo_phase_structure_build/4000/64/32/32	47.901 ms	47.966 ms	+0.14%	regressed
bench_diffgeo_pipeline/1000/50/32/32	121.459 ms	122.056 ms	+0.49%	regressed
bench_diffgeo_pipeline/4000/64/32/32	833.608 ms	836.911 ms	+0.40%	regressed