What problem does it solve?
Flash Attention reduces the high time and memory cost of transformer self-attention, especially for long sequences that otherwise run into slowdowns and GPU out-of-memory errors.
Core Features & Use Cases
- Speedup for attention: Delivers 2–4x faster attention (or more on supported GPUs) by using IO-aware tiling and recomputation.
- Memory efficiency for long sequences: Cuts attention memory usage dramatically (reported 10–20x reduction) so longer contexts can fit.
- Multiple integration paths: Works via PyTorch native SDPA (PyTorch 2.2+), the flash-attn library (advanced attention features), and FlashAttention-3 FP8 on H100.
Use case example: You are training or serving a Llama-/GPT-style model and need to handle 4K–32K tokens per request, but standard attention is too memory-hungry—use this skill to enable Flash Attention and unlock longer contexts on the same hardware.
Quick Start
Use the AI to show how to switch your transformer attention to PyTorch native Flash Attention using F.scaled_dot_product_attention (and verify the speed/memory change).