GPU Utilization

GPU Utilization refers to the percentage of time a Graphics Processing Unit’s compute units are actively performing calculations versus being idle or waiting for data. In the context of large-language-model (LLM) inference and training, high utilization is critical for cost-efficiency and throughput.

Key Bottlenecks

  • Memory Bandwidth: Often the limiting factor in inference, where the GPU waits for weights and activations to be fetched from VRAM.
  • Compute Bound: Occurs when the GPU is fully engaged in matrix multiplications, typical in pre-fill phases or training.
  • KV-Cache Management: Inefficient handling of Key-Value caches can lead to fragmented memory usage and reduced effective utilization during long-context generation.

Optimization Strategies

  • Batching: Dynamic batching groups multiple requests to maximize parallel processing.
  • PagedAttention: Techniques like those used in vLLM reduce memory fragmentation.
  • DualPath Architecture: Recent advancements focus on decoupling compute paths to optimize throughput specifically for KV-Cache operations.

Recent Developments

References