A multi-agent kernel loop optimized three Gemma-4-12B decode kernels for an unfamiliar NPU, hitting a 9.293x geomean speedup on a scarce shared device
AspireAI community · arXiv (MICRO 2026 competition)
Frontier models write correct CUDA kernels for familiar hardware but collapse on accelerators whose architecture and programming language they have rarely seen, so this case study targets the FuriosaAI RNGD NPU and its sparsely documented Rust DSL. The agent loop built its own target knowledge: it wrote and checked a summary of the DSL documentation, microbenchmarked the chip, recorded compiler-derived legality rules, and revisited that knowledge when the toolchain changed, then searched over per-kernel Design Trees with cheap screening before spending scarce device time. Over 12 days on a shared device it optimized three Gemma-4-12B decode kernels to a 9.293x geomean speedup over the official baseline, each landing within 1.25x of the cycles needed just to move its own weights, and the entry was part of the NPU Model Optimization Competition at MICRO 2026. The honest limit is hardware scope: this is one accelerator and one DSL, with the device shared between two jobs at a time.
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Two sparse-autoencoder analyses have resisted scaling: matching semantically similar features across layers, and compressing large feature circuits into interpretable supernodes. This paper argues both are the same underlying problem, estimating semantic distances between SAE features that sit on different activation manifolds. Its representation treats each feature not as a single decoder vector but as an activation-weighted distribution over the hidden states expressing it, projects those distributions into a shared reference space, and compares them with Wasserstein distance. The representation is proved invariant to activation rescaling and stable under perturbation, and recovers true matches under finite-sample margin conditions. Empirically it outperformed decoder-vector and LLM-based baselines and captured subtle functional distinctions between related features, and it compressed large feature circuits into interpretable supernodes automatically. The limitation is that this is interpretability tooling: the paper demonstrates better feature matching and circuit compression, not that downstream interpretability claims become more accurate.