Gyges: Dynamic Cross-Instance Parallelism Transformation for Efficient LLM Inference

Abstract: Efficiently processing the dynamics of requests, especially the context length variance, is important in LLM serving scenarios. However, there is an intrinsic trade-off: while leveraging parallelism strategies, such as Tensor Parallelism (TP), can coordinate multiple GPUs to accommodate larger context lengths, it inevitably results in degraded overall throughput. In this paper, we propose Cross-Instance Parallelism Transformation (Gyges), which adaptively adjusts the parallelism strategies of running instances to align with the dynamics of incoming requests. We design (1) a page-friendly, header-centric layout to accelerate KV cache transformations; (2) dedicated weight padding to accelerate model weight transformations; and (3) a transformation-aware scheduler to cooperatively schedule requests and parallelism transformations, optimizing the overall performance. Evaluations using real-world traces show that Gyges improves throughput by 1.75x-6.57x compared to state-of-the-art solutions.