Show Notes
GPU hardware is only as useful as the code running on it. For deep learning teams chasing faster training loops and tighter inference times, the bottleneck isn't always the model or the data pipeline — sometimes it's the abstraction layer between your workload and the silicon. This episode of
Development explores
building custom CUDA kernels for deep learning performance, making the case that going low-level isn't just for systems programmers — it's a practical tool for anyone serious about squeezing the most out of their GPU.
The episode walks through the full arc of writing, integrating, and optimizing a custom CUDA kernel, covering:
- What CUDA kernels actually are — functions that execute simultaneously across thousands of GPU threads, each handling a small slice of your data, rather than running once on a single processor.
- Why built-in library kernels fall short — PyTorch and TensorFlow ship highly tuned kernels for common operations, but those kernels must handle every possible edge case; a custom kernel only has to handle yours, and that specificity is where the speed lives.
- The GPU execution model — understanding how threads, blocks, shared memory, and grids fit together is the foundation for writing kernels that are actually efficient rather than just correct.
- Key performance concepts — memory coalescing (keeping consecutive threads on consecutive addresses), shared memory (loading data once for a whole block instead of hitting slow global memory repeatedly), and warp efficiency (minimizing branch divergence so no threads sit idle).
- Integrating with existing frameworks — both PyTorch and TensorFlow offer real extension mechanisms so a custom kernel can be called from Python just like any native operation, keeping it inside your actual training pipeline.
- Testing, debugging, and profiling — GPU bugs can be subtle and nearly correct; rigorous output verification and tools like NVIDIA Nsight Systems and Nsight Compute are essential for catching errors and pinpointing the next bottleneck to fix.
The episode is candid about the trade-off: custom kernels mean taking on memory management, thread organization, and low-level error handling — real costs that generic library calls spare you from. But for teams working with novel architectures, non-standard data transformations, or production latency targets that off-the-shelf ops can't meet, that investment in control pays dividends that compound across every training run. More from the show:
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What is DEV?
Software and web development from the side that has to ship it and then live with it. Architecture decisions with a cost attached, scoping, technical debt, hiring and vendor selection, and the AI tooling question every engineering team is now answering whether they planned to or not.
Each episode takes one decision — rewrite or refactor, framework choice, build versus buy, how to scope a fixed-bid project honestly — and works through the tradeoffs, including the ones that only show up in year two. Written for engineering leads, technical founders and the people who fund them. Five or six minutes, no hand-waving.
Topics include rewrite versus refactor, build versus buy, scoping fixed-bid work honestly, technical debt you should keep, framework and platform choices, hiring and vendor selection, code review culture, and where AI tooling actually helps.
Produced by DEV.co, web and software development. Full details, services and further reading at https://dev.co