Flash-Decoding: Optimizing Long-Context Inference
As Large Language Models move toward context windows of millions of tokens, the standard KV cache management becomes a bottleneck. Flash-Decoding builds upon Flash-Attention to optimize the decoding phase, which is traditionally serial and memory-bound.
How it Works
Instead of processing the entire KV cache in a single thread, Flash-Decoding:
- Splits the keys and values into smaller blocks.
- Computes the attention for each block in parallel.
- Rescales and merges the partial results using a final reduction step.
Performance Gains
This parallelization results in a nearly 10x speedup for inference on long sequences, enabling practical use cases for document-level reasoning and multi-modal context processing.