cargo-bench(1)
NAME
cargo-bench --- Execute benchmarks of a package
SYNOPSIS
cargo bench [options] [benchname] [-- bench-options]
DESCRIPTION
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 a
special executable by linking your code with libtest. The executable
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, regardless of whether the harness is libtest or a custom harness.
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.
Working directory of benchmarks
The working directory of every benchmark is set to the root directory of the
package the benchmark belongs to.
Setting the working directory of benchmarks to the package's root directory
makes it possible for benchmarks to reliably access the package's files using
relative paths, regardless from where cargo bench was executed from.
OPTIONS
Benchmark Options
Package Selection
By default, when no package selection options are given, the packages selected
depend on the selected manifest file (based on the current working directory if
--manifest-path is not given). If the manifest is the root of a workspace then
the workspaces default members are selected, otherwise only the package defined
by the manifest will be selected.
The default members of a workspace can be set explicitly with the
workspace.default-members key in the root manifest. If this is not set, a
virtual workspace will include all workspace members (equivalent to passing
--workspace), and a non-virtual workspace will include only the root crate itself.
Target Selection
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, replacing the example's main function with
the libtest harness.
Setting targets to bench = false will stop them from being benchmarked by
default. Target selection options that take a target by name (such as
--example foo) ignore the bench flag and will always benchmark the given
target.
See Configuring a target for more information on per-target settings.
Binary targets are automatically built if there is an integration test or
benchmark being selected to benchmark. This allows an integration
test to execute the binary to exercise and test its behavior.
The CARGO_BIN_EXE_<name>
environment variable
is set when the integration test is built so that it can use the
env macro to locate the
executable.
Passing target selection flags will benchmark only the specified targets.
Note that --bin, --example, --test and --bench flags also
support common Unix glob patterns like *, ? and []. However, to avoid your
shell accidentally expanding glob patterns before Cargo handles them, you must
use single quotes or double quotes around each glob pattern.
Feature Selection
The feature flags allow you to control which features are enabled. When no
feature options are given, the default feature is activated for every
selected package.
See the features documentation for more details.
Compilation Options
Output Options
Display 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 --no-capture to the benchmark binaries:
cargo bench -- --no-capture
Manifest Options
Common Options
Miscellaneous Options
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.
While cargo bench involves compilation, it does not provide a --keep-going
flag. Use --no-fail-fast to run as many benchmarks as possible without
stopping at the first failure. To "compile" as many benchmarks as possible, use
--benches to build benchmark binaries separately. For example:
cargo build --benches --release --keep-going
cargo bench --no-fail-fast
ENVIRONMENT
See the reference for details on environment variables that Cargo reads.
EXIT STATUS
0: Cargo succeeded.101: Cargo failed to complete.
EXAMPLES
-
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 -- some_benchmark