µbench

"micro bench", as in: microcontroller

what

This is a tiny crate that attempts to help you benchmark things running on microcontrollers.

This is not a particularly good crate. It:

• does not attempt to be statistically rigorous
• does not try to mitigate the effects of CPU caches/frequency scaling/OS context switches, etc. on benchmarks
• does not really provide machinery for host-side processing
• does not attempt to mimic the output of the test::bench module
• does not make use of the defmt ecosystem [^1] (in order to support boards that do not have probe-rs support)

[^1]: Nothing precludes you from writing a Reporter that makes use of defmt machinery but this crate does not ship with one. The default reporter is naive, uses core::fmt, and is space inefficient.

µbench is very much intended to be a stopgap; it is my sincere hope that this crate will be obviated in the near future.

However, as of this writing, there seems to be a real dearth of solutions aimed at users who just want to: run some code on their device and get back cycle counts, without needing to spin up a debugger. Hence this crate.

The closest thing out there (that I am aware of) that serves this use case is liar which is, unfortunately, just a tiny bit too barebones when the std feature is disabled.

how does it work?

(overview of the traits:

• Benchmark which can be: fn, closure impling FnMut, custom impl with setup + teardown
  • these take some Inp data by reference
• BenchmarkRunner lets you actually run benchmarks; two kinds
  • single (constructible with single)
    • exactly one Benchmark impl
  • suite (constructible with suite)
    • zero or more Benchmark impls that are all run on the same input data
  • each of these also take some impl IntoIterator<Item = T> as an input source where T: Debug
    • this can be things like a range (0..10), an array (["hey", "there"]), an iterator ((0..10).map(|x| 2u32.pow(x))), etc.
• to actually run the benchmarks you need:
  • a Metric
    • some way to actually measure the benchmarks; i.e. time, cycle counts
  • a Reporter
    • some way to report out the results of the benchmarking )

usage