Command-Line Options

Note: If cargo bench fails with an error message about an unknown argument, see the FAQ. benchmarks accept a number of custom command-line parameters. This is a list of the most common options. Run cargo bench -- -h to see a full list.

  • To filter benchmarks, use cargo bench -- <filter> where <filter> is a regular expression matching the benchmark ID. For example, running cargo bench -- fib_20 would only run benchmarks whose ID contains the string fib_20, while cargo bench -- fib_\d+ would also match fib_300.
  • To print more detailed output, use cargo bench -- --verbose
  • To disable colored output, use cargo bench -- --color never
  • To disable plot generation, use cargo bench -- --noplot
  • To iterate each benchmark for a fixed length of time without saving, analyzing or plotting the results, use cargo bench -- --profile-time <num_seconds>. This is useful when profiling the benchmarks. It reduces the amount of unrelated clutter in the profiling results and prevents' normal dynamic sampling logic from greatly increasing the runtime of the benchmarks.
  • To save a baseline, use cargo bench -- --save-baseline <name>. To compare against an existing baseline, use cargo bench -- --baseline <name>. For more on baselines, see below.
  • To test that the benchmarks run successfully without performing the measurement or analysis (eg. in a CI setting), use cargo test --benches.
  • To override the default plotting backend, use cargo bench -- --plotting-backend gnuplot or cargo bench --plotting-backend plotters. gnuplot is used by default if it is installed.
  • To change the CLI output format, use cargo bench -- --output-format <name>. Supported output formats are:
  • criterion - Use Criterion's normal output format
  • bencher - An output format similar to the output produced by the bencher crate or nightly libtest benchmarks. Though this provides less information than the criterion format, it may be useful to support external tools that can parse this output.


By default, will compare the measurements against the previous run (if any). Sometimes it's useful to keep a set of measurements around for several runs. For example, you might want to make multiple changes to the code while comparing against the master branch. For this situation, supports custom baselines.

  • --save-baseline <name> will compare against the named baseline, then overwrite it.
  • --baseline <name> will compare against the named baseline without overwriting it.
  • --load-baseline <name> will load the named baseline as the new data set rather than the previous baseline.

Using these options, you can manage multiple baseline measurements. For instance, if you want to compare against a static reference point such as the master branch, you might run:

git checkout master
cargo bench -- --save-baseline master
git checkout feature
cargo bench -- --save-baseline feature
git checkout optimizations

# Some optimization work here

# Measure again
cargo bench
# Now compare against the stored baselines without overwriting it or re-running the measurements
cargo bench -- --load-baseline new --baseline master
cargo bench -- --load-baseline new --baseline feature