# Arithmetic intensity

> Arithmetic intensity: Operations done per byte read from memory. Low intensity means bandwidth is the limit; high intensity means compute is.

Canonical: https://llmdojo.dev/glossary/arithmetic-intensity

Also called operations per byte.

Operations done per byte read from memory. Low intensity means bandwidth is the limit; high intensity means compute is.

Learn it in the lesson: [Two kinds of slow](https://llmdojo.dev/learn/inference-optimization/where-the-time-goes/two-kinds-of-slow) (Inference and Model Optimization · Where the Time Goes: Memory, Compute and Batching).

## Interview questions about Arithmetic intensity

- [What's the difference between compute-bound and memory bandwidth-bound work, and which one is decode?](https://llmdojo.dev/interview/q/what-s-the-difference-between-compute-bound-and-memory-bandwidth-bound-work)
- [How would you show, on a given machine, that decode is bandwidth-bound and prefill compute-bound?](https://llmdojo.dev/interview/q/how-would-you-show-on-a-given-machine-that-decode-is-bandwidth)
- [Your LLM training and serving is slow. Reason about memory-bound versus compute-bound kernels, the cost of materializing the attention matrix, HFU versus MFU, and which GPU profiling signals you'd read.](https://llmdojo.dev/interview/q/your-llm-training-and-serving-is-slow-reason-about-memory-bound-versus)

## Related
- [Compute-bound](https://llmdojo.dev/glossary/compute-bound)
- [Memory bandwidth-bound](https://llmdojo.dev/glossary/bandwidth-bound)
- [Roofline](https://llmdojo.dev/glossary/roofline)
- [Model bandwidth utilization (MBU)](https://llmdojo.dev/glossary/mbu)
- [Continuous batching](https://llmdojo.dev/glossary/continuous-batching)
- [Glossary of every term](https://llmdojo.dev/glossary)