bench/decimal tutorial

This page shows how to run the IEEE decimal arithmetic benchmarks and how to read their output. The suite compares implementation paths on identical inputs with paired measurements; see the bench tutorial for the toolkit and the artifact format.

Quick start

From the repository root:

just bench decimal

The runner executes the skipped performance tests of src/bench/decimal on the native target in release mode and writes .tmp/bench/SUITE.jsonl (all observations) and .tmp/bench/SUITE.analysis.txt (the reduced lines), where SUITE is the name given to just bench.

Everyday tasks

Read the analysis lines

The analysis file contains MAREMARK_HOTSPOT=decimal/OP/DATASET core_pct=… full_pct=…. A core_pct value is the median paired difference between the core path and the kernel, in percent of the kernel’s median time; full_pct is the same for the checked path against the core path. Positive values mean the higher layer is slower.

Check the plans without measuring

sh tools/run_moon_clean_exec.sh test src/bench/decimal --target native

runs only the plan tests, which compile every specification.

Going further

• Change datasets or implementations in the *_test.mbt files; keep the reference oracle so a faster but wrong path fails the run.
• Compare two runs only when their recorded environments agree.
• The performance audit and the performance/ pages summarize measured results.

Common pitfalls

• Benchmarks are skipped in normal moon test runs; use just bench.
• Results depend on the machine; percentages are more stable than absolute microseconds.

Next steps

• bench/decimal API
• bench/decimal design
• bench design for the statistics.