Interactive models
The figures make a few important relationships manipulable. Predict the direction before changing a value; treat the result as a lower bound or consistency check, never as a substitute for measurement.
Roofline explorer
Connect peak arithmetic, memory bandwidth, and arithmetic intensity.
Next question: if measurement is well below this roof, which dependency, instruction, parallelism, or traffic assumption is wrong?
KV-cache capacity
Estimate cache memory for a decoder using layers, KV heads, head dimension, precision, tokens, and concurrency.
This excludes block tail waste, page tables, allocator metadata, prefix sharing, tensor-parallel sharding, workspaces, and safety headroom. Add those before sizing a service.
Predict
Write the regime, trend, or break-even point before touching a profiler.
Measure
Capture a controlled baseline with correctness and workload context.
Explain
Reconcile model and observation. The mismatch is often the lesson.