通过约束二值优化,智能删减Transformer块实现大模型高效压缩。
LLM Compression by Block Removal with Constrained Binary Optimization
- 将删块压缩建模为可映射到自旋玻璃系统的约束二值优化问题。
- 在Llama-3.3-70B上实现50%压缩,MMLU得分提升23个百分点。
- 适用于任意架构,对复杂结构模型仍保持优异性能。
本文将大型语言模型(LLMs)通过最优删除Transformer块(块移除)实现压缩的问题,建模为约束二值优化(CBO)问题,并将其映射到物理系统(伊辛玻璃),其能量可作为下游模型性能的强代理。该方法能高效排序大量候选删块配置,获得多个高质量、非平凡解,超越仅移除连续区域的方法。在深度压缩场景下表现突出,如对Llama-3.3-70B-Instruct实现50%压缩时,MMLU基准得分相比其他最先进(SOTA)删块方法提升近23个百分点。在轻度压缩下,于Llama-3.1-8B-Instruct、Qwen3-14B(含重训练前后)及Llama-3.3-70B-Instruct等模型上表现与现有方法相当。该方法计算高效,仅需在校准数据集上进行少量激活参数的前向与反向传播。此外,我们证明使用优质启发式求解器可在极短时间内获得下游任务表现良好的解,当精确求解不可行时尤为适用。该方法可直接应用于任何架构,我们在NVIDIA-Nemotron-3-Nano-30B-A3B-FP8模型上验证其通用性,该模型具有高度非均匀且复杂的块结构,在移除2个注意力层或3个专家混合层时,优于当前最先进方法,在AIME25和GPQA任务上表现更佳。
原文摘要 · Abstract (English)
In this paper, we formulate the compression of large language models (LLMs) by optimally deleting transformer blocks (``block removal'') as a constrained binary optimization (CBO) problem that can be mapped to a physical system (Ising glass), whose energies are a strong proxy for downstream model performance. This formulation enables an efficient ranking of a large number of candidate block-removal configurations yielding many high-quality, non-trivial solutions beyond those only removing consecutive regions. Our method performs strongly in the deep compression regime, such as for 50% compression of Llama-3.3-70B-Instruct, where we achieve an almost 23 percentage point increase on the MMLU benchmark compared to other state-of-the-art (SOTA) block-removal methods. For lighter compression, it performs on par with those methods across several benchmarks for Llama-3.1-8B-Instruct, Qwen3-14B (both before and after retraining), as well as Llama-3.3-70B-Instruct. The approach is computationally efficient and requires only forward and backward passes on a calibration dataset for a few active parameters. Additionally, we demonstrate that using good heuristic solvers for the CBO problem provides solutions that perform well on downstream tasks in negligible runtime when it is unfeasible to solve the problem exactly. The method can be readily applied to any architecture. We illustrate this generality on the recent NVIDIA-Nemotron-3-Nano-30B-A3B-FP8 model, which exhibits a highly inhomogeneous and challenging block structure, and where we outperform SOTA for AIME25 and GPQA when removing either 2 attention layers or 3 mixture-of-experts layers.
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