{{*set actionverb="Benchmark"}} {{*set nouns="benchmarks"}}
cargo-bench - Execute benchmarks of a package
cargo bench
[options] [benchname] [--
bench-options]
Compile and execute benchmarks.
The benchmark filtering argument benchname and all the arguments following
the two dashes (--
) are passed to the benchmark binaries and thus to
libtest (rustc's built in unit-test and micro-benchmarking framework). If
you are passing arguments to both Cargo and the binary, the ones after --
go
to the binary, the ones before go to Cargo. For details about libtest's
arguments see the output of cargo bench -- --help
and check out the rustc
book's chapter on how tests work at
https://doc.rust-lang.org/rustc/tests/index.html.
As an example, this will run only the benchmark named foo
(and skip other
similarly named benchmarks like foobar
):
cargo bench -- foo --exact
Benchmarks are built with the --test
option to rustc
which creates an
executable with a main
function that automatically runs all functions
annotated with the #[bench]
attribute. Cargo passes the --bench
flag to
the test harness to tell it to run only benchmarks.
The libtest harness may be disabled by setting harness = false
in the target
manifest settings, in which case your code will need to provide its own main
function to handle running benchmarks.
Note: The
#[bench]
attribute is currently unstable and only available on the nightly channel. There are some packages available on crates.io that may help with running benchmarks on the stable channel, such as Criterion.
By default, cargo bench
uses the bench
profile, which enables
optimizations and disables debugging information. If you need to debug a
benchmark, you can use the --profile=dev
command-line option to switch to
the dev profile. You can then run the debug-enabled benchmark within a
debugger.
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When no target selection options are given, cargo bench
will build the
following targets of the selected packages:
- lib — used to link with binaries and benchmarks
- bins (only if benchmark targets are built and required features are available)
- lib as a benchmark
- bins as benchmarks
- benchmark targets
The default behavior can be changed by setting the bench
flag for the target
in the manifest settings. Setting examples to bench = true
will build and
run the example as a benchmark. Setting targets to bench = false
will stop
them from being benchmarked by default. Target selection options that take a
target by name ignore the bench
flag and will always benchmark the given
target.
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{{#options}}
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{{/options}}
{{#options}} {{> options-target-dir }} {{/options}}
By default the Rust test harness hides output from benchmark execution to keep
results readable. Benchmark output can be recovered (e.g., for debugging) by
passing --nocapture
to the benchmark binaries:
cargo bench -- --nocapture
{{#options}}
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{{/options}}
{{#options}} {{> options-manifest-path }}
{{> options-locked }} {{/options}}
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The --jobs
argument affects the building of the benchmark executable but
does not affect how many threads are used when running the benchmarks. The
Rust test harness runs benchmarks serially in a single thread.
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-
Build and execute all the benchmarks of the current package:
cargo bench
-
Run only a specific benchmark within a specific benchmark target:
cargo bench --bench bench_name -- modname::some_benchmark
{{man "cargo" 1}}, {{man "cargo-test" 1}}