Deep systems understanding · Study map 43 of 85
Fusion and CUDA graphs: less dispatch, fewer round trips
Suggested preparation: FlashAttention: avoid writing the giant scratchpad
Picture it
Imagine an assembly line where a part is repeatedly taken off the belt, carried to a supervisor for inspection, and then put back. Fusion merges these steps, keeping the part in the worker's hands for multiple modifications without the wasteful handoffs. CUDA graphs take this a step further by recording the entire symphony of tasks into a single sheet of music. Instead of the conductor calling out each note individually, the orchestra plays the whole fluid sequence uninterrupted.
What to understand
- Kernel fusion, layouts, tiling, and mixed precision
- Graph capture, shape buckets, padding, compilation, and warmup
Follow the references
1 · Tutorials
Triton · GPU programming tutorials ↗Compare vector addition, fused softmax, and matrix multiplication tutorials.
2 · Documentation
vLLM · Optimization and tuning ↗Read the CUDA graph and compilation guidance for your engine version.
Make it concrete
Compare graph-enabled and eager execution on one supported engine. Sweep batch shapes; record latency and extra memory as well as capture/warmup time.
You understand it when…
Why might a shape-changing workload reduce the value of a captured graph?
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