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feat(cuda): add a FastLanes delta decode kernel - #9535

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joseph-isaacs merged 2 commits into
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ji/cuda-delta-kernel
Aug 25, 2026
Merged

feat(cuda): add a FastLanes delta decode kernel#9535
joseph-isaacs merged 2 commits into
developfrom
ji/cuda-delta-kernel

bench(cuda): measure FastLanes delta decode

0b47892
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CodSpeed HQ / CodSpeed Performance Analysis failed Aug 24, 2026 in 0s

Performance Regression: -12.05%

⚠️ Unknown Walltime execution environment detected

Using the Walltime instrument on standard Hosted Runners will lead to inconsistent data.

For the most accurate results, we recommend using CodSpeed Macro Runners: bare-metal machines fine-tuned for performance measurement consistency.

⚠️ Different runtime environments detected

Some benchmarks with significant performance changes were compared across different runtime environments,
which may affect the accuracy of the results.

Open the report in CodSpeed to investigate

⚡ 1 improved benchmark
❌ 3 regressed benchmarks
✅ 2019 untouched benchmarks
⏩ 12 skipped benchmarks1
🗄️ 1 archived benchmark run2

Warning

Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

Mode Benchmark BASE HEAD Efficiency
WallTime words_gather_dispatch_avx512[1024] 9 ns 13 ns -30.77%
WallTime words_gather_scalar_avx2[65536] 8.2 µs 9.4 µs -12.03%
Simulation cold_misaligned[(16, 64)] 382.7 µs 429.1 µs -10.82%
WallTime cuda/bitpacked_u16/unpack/5bw[100M] 613.2 µs 556.8 µs +10.14%

Tip

Investigate this regression by commenting @codspeedbot fix this regression on this PR, or directly use the CodSpeed MCP with your agent.


Comparing ji/cuda-delta-kernel (0b47892) with develop (62648ef)

Open in CodSpeed

Footnotes

  1. 12 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports.

  2. 1 benchmark was run, but is now archived. If it was deleted in another branch, consider rebasing to remove it from the report. Instead if it was added back, click here to restore it.