Benchmarks

#[builder] generates code that is easily optimizable by the compiler. This has been tested by the benchmarks below. The benchmarks compare regular positional function call syntax and builder syntax for functions annotated with #[builder].

In many cases rustc generates the same assembly code for the builder syntax as it would for a regular function call. Even when generated assembly differs, the performance differences are negligible.

TIP

Don't take these microbenchmarks for granted. Do your own performance measurements in your application in real conditions. Feel free to open an issue if you find performance problems in bon.

Wallclock statistics

Benchmark	Description	Assembly output	Run time
args_3	3 args of primitive types	Equal	regular: 6.6536ns builder: 6.6494ns
args_5	5 args of primitive types	Equal	regular: 7.9592ns builder: 7.9731ns
args_10	10 args of primitive types	Ordering diff	regular: 18.082ns builder: 18.217ns
args_10_structs	10 args of primitive types and structs	Equal	regular: 5.0784ns builder: 5.0481ns
args_10_alloc	10 args of primitive and heap-allocated types	Instructions diff	regular: 86.090ns builder: 86.790ns
args_20	20 args of primitive types	Ordering diff	regular: 37.381ns builder: 37.623ns

High-precision statistics

Benchmark	Instructions count	L1 accesses	L2 accesses	RAM accesses
args_3	regular: 106 builder: 106	regular: 136 builder: 136	regular: 2 builder: 2	regular: 4 builder: 4
args_5	regular: 124 builder: 124	regular: 161 builder: 161	regular: 1 builder: 1	regular: 9 builder: 9
args_10	regular: 281 builder: 281	regular: 381 builder: 380	regular: 2 builder: 2	regular: 19 builder: 20
args_10_structs	regular: 73 builder: 73	regular: 108 builder: 108	regular: 2 builder: 2	regular: 10 builder: 10
args_10_alloc	regular: 2025 builder: 2026	regular: 2823 builder: 2823	regular: 3 builder: 2	regular: 35 builder: 35
args_20	regular: 554 builder: 554	regular: 768 builder: 769	regular: 3 builder: 3	regular: 34 builder: 33

Conditions

The code was compiled with opt-level = 3 and debug = 0.

Hardware

The benchmarks were run on a dedicated root server AX51-NVMe on Hetzner.

• OS: Ubuntu 22.04.4 (Linux 5.15.0-76-generic)
• CPU: AMD Ryzen 7 3700X 8-Core Processor (x86_64)
• RAM: 62.8 GiB

References

The source code of the benchmarks is available here.