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.

       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
          <https://doc.rust-lang.org/nightly/unstable-book/library-features/test.html>
          is currently unstable and only available on the nightly channel
          <https://doc.rust-lang.org/book/appendix-07-nightly-rust.html>. There
          are some packages available on crates.io
          <https://crates.io/keywords/benchmark> that may help with running
          benchmarks on the stable channel, such as Criterion
          <https://crates.io/crates/criterion>.

       By default, cargo bench uses the bench profile
       <https://doc.rust-lang.org/cargo/reference/profiles.html#bench>, 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
       --no-run
           Compile, but don’t run benchmarks.

       --no-fail-fast
           Run all benchmarks regardless of failure. Without this flag, Cargo
           will exit after the first executable fails. The Rust test harness
           will run all benchmarks within the executable to completion, this
           flag only applies to the executable as a whole.

   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.

       -p spec…, --package spec…
           Benchmark only the specified packages. See cargo-pkgid(1) for the
           SPEC format. This flag may be specified multiple times and supports
           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
           pattern.

       --workspace
           Benchmark all members in the workspace.

       --all
           Deprecated alias for --workspace.

       --exclude SPEC…
           Exclude the specified packages. Must be used in conjunction with the
           --workspace flag. This flag may be specified multiple times and
           supports 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 pattern.

   Target Selection
       When no target selection options are given, cargo bench will build the
       following targets of the selected packages:

       o  lib — used to link with binaries and benchmarks

       o  bins (only if benchmark targets are built and required features are
          available)

       o  lib as a benchmark

       o  bins as benchmarks

       o  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 bencharmked
       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
       <https://doc.rust-lang.org/cargo/reference/cargo-targets.html#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
       <https://doc.rust-lang.org/cargo/reference/environment-variables.html#environment-variables-cargo-sets-for-crates>
       is set when the integration test is built so that it can use the env
       macro <https://doc.rust-lang.org/std/macro.env.html> 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.

       --lib
           Benchmark the package’s library.

       --bin name…
           Benchmark the specified binary. This flag may be specified multiple
           times and supports common Unix glob patterns.

       --bins
           Benchmark all binary targets.

       --example name…
           Benchmark the specified example. This flag may be specified multiple
           times and supports common Unix glob patterns.

       --examples
           Benchmark all example targets.

       --test name…
           Benchmark the specified integration test. This flag may be specified
           multiple times and supports common Unix glob patterns.

       --tests
           Benchmark all targets in test mode that have the test = true
           manifest flag set. By default this includes the library and binaries
           built as unittests, and integration tests. Be aware that this will
           also build any required dependencies, so the lib target may be built
           twice (once as a unittest, and once as a dependency for binaries,
           integration tests, etc.). Targets may be enabled or disabled by
           setting the test flag in the manifest settings for the target.

       --bench name…
           Benchmark the specified benchmark. This flag may be specified
           multiple times and supports common Unix glob patterns.

       --benches
           Benchmark all targets in benchmark mode that have the bench = true
           manifest flag set. By default this includes the library and binaries
           built as benchmarks, and bench targets. Be aware that this will also
           build any required dependencies, so the lib target may be built
           twice (once as a benchmark, and once as a dependency for binaries,
           benchmarks, etc.). Targets may be enabled or disabled by setting the
           bench flag in the manifest settings for the target.

       --all-targets
           Benchmark all targets. This is equivalent to specifying --lib --bins
           --tests --benches --examples.

   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
       <https://doc.rust-lang.org/cargo/reference/features.html#command-line-feature-options>
       for more details.

       -F features, --features features
           Space or comma separated list of features to activate. Features of
           workspace members may be enabled with package-name/feature-name
           syntax. This flag may be specified multiple times, which enables all
           specified features.

       --all-features
           Activate all available features of all selected packages.

       --no-default-features
           Do not activate the default feature of the selected packages.

   Compilation Options
       --target triple
           Benchmark for the given architecture. The default is the host
           architecture. The general format of the triple is
           <arch><sub>-<vendor>-<sys>-<abi>. Run rustc --print target-list for
           a list of supported targets. This flag may be specified multiple
           times.

           This may also be specified with the build.target config value
           <https://doc.rust-lang.org/cargo/reference/config.html>.

           Note that specifying this flag makes Cargo run in a different mode
           where the target artifacts are placed in a separate directory. See
           the build cache
           <https://doc.rust-lang.org/cargo/guide/build-cache.html>
           documentation for more details.

       --profile name
           Benchmark with the given profile. See the the reference
           <https://doc.rust-lang.org/cargo/reference/profiles.html> for more
           details on profiles.

       --ignore-rust-version
           Benchmark the target even if the selected Rust compiler is older
           than the required Rust version as configured in the project’s
           rust-version field.

       --timings=fmts
           Output information how long each compilation takes, and track
           concurrency information over time. Accepts an optional
           comma-separated list of output formats; --timings without an
           argument will default to --timings=html. Specifying an output format
           (rather than the default) is unstable and requires
           -Zunstable-options. Valid output formats:

           o  html (unstable, requires -Zunstable-options): Write a
              human-readable file cargo-timing.html to the target/cargo-timings
              directory with a report of the compilation. Also write a report
              to the same directory with a timestamp in the filename if you
              want to look at older runs. HTML output is suitable for human
              consumption only, and does not provide machine-readable timing
              data.

           o  json (unstable, requires -Zunstable-options): Emit
              machine-readable JSON information about timing information.

   Output Options
       --target-dir directory
           Directory for all generated artifacts and intermediate files. May
           also be specified with the CARGO_TARGET_DIR environment variable, or
           the build.target-dir config value
           <https://doc.rust-lang.org/cargo/reference/config.html>. Defaults to
           target in the root of the workspace.

   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 --nocapture to the benchmark binaries:

           cargo bench -- --nocapture

       -v, --verbose
           Use verbose output. May be specified twice for “very verbose”
           output which includes extra output such as dependency warnings and
           build script output. May also be specified with the term.verbose
           config value
           <https://doc.rust-lang.org/cargo/reference/config.html>.

       -q, --quiet
           Do not print cargo log messages. May also be specified with the
           term.quiet config value
           <https://doc.rust-lang.org/cargo/reference/config.html>.

       --color when
           Control when colored output is used. Valid values:

           o  auto (default): Automatically detect if color support is
              available on the terminal.

           o  always: Always display colors.

           o  never: Never display colors.

           May also be specified with the term.color config value
           <https://doc.rust-lang.org/cargo/reference/config.html>.

       --message-format fmt
           The output format for diagnostic messages. Can be specified multiple
           times and consists of comma-separated values. Valid values:

           o  human (default): Display in a human-readable text format.
              Conflicts with short and json.

           o  short: Emit shorter, human-readable text messages. Conflicts with
              human and json.

           o  json: Emit JSON messages to stdout. See the reference
              <https://doc.rust-lang.org/cargo/reference/external-tools.html#json-messages>
              for more details. Conflicts with human and short.

           o  json-diagnostic-short: Ensure the rendered field of JSON messages
              contains the “short” rendering from rustc. Cannot be used
              with human or short.

           o  json-diagnostic-rendered-ansi: Ensure the rendered field of JSON
              messages contains embedded ANSI color codes for respecting
              rustc’s default color scheme. Cannot be used with human or
              short.

           o  json-render-diagnostics: Instruct Cargo to not include rustc
              diagnostics in JSON messages printed, but instead Cargo itself
              should render the JSON diagnostics coming from rustc. Cargo’s
              own JSON diagnostics and others coming from rustc are still
              emitted. Cannot be used with human or short.

   Manifest Options
       --manifest-path path
           Path to the Cargo.toml file. By default, Cargo searches for the
           Cargo.toml file in the current directory or any parent directory.

       --frozen, --locked
           Either of these flags requires that the Cargo.lock file is
           up-to-date. If the lock file is missing, or it needs to be updated,
           Cargo will exit with an error. The --frozen flag also prevents Cargo
           from attempting to access the network to determine if it is
           out-of-date.

           These may be used in environments where you want to assert that the
           Cargo.lock file is up-to-date (such as a CI build) or want to avoid
           network access.

       --offline
           Prevents Cargo from accessing the network for any reason. Without
           this flag, Cargo will stop with an error if it needs to access the
           network and the network is not available. With this flag, Cargo will
           attempt to proceed without the network if possible.

           Beware that this may result in different dependency resolution than
           online mode. Cargo will restrict itself to crates that are
           downloaded locally, even if there might be a newer version as
           indicated in the local copy of the index. See the cargo-fetch(1)
           command to download dependencies before going offline.

           May also be specified with the net.offline config value
           <https://doc.rust-lang.org/cargo/reference/config.html>.

   Common Options
       +toolchain
           If Cargo has been installed with rustup, and the first argument to
           cargo begins with +, it will be interpreted as a rustup toolchain
           name (such as +stable or +nightly). See the rustup documentation
           <https://rust-lang.github.io/rustup/overrides.html> for more
           information about how toolchain overrides work.

       --config KEY=VALUE or PATH
           Overrides a Cargo configuration value. The argument should be in
           TOML syntax of KEY=VALUE, or provided as a path to an extra
           configuration file. This flag may be specified multiple times. See
           the command-line overrides section
           <https://doc.rust-lang.org/cargo/reference/config.html#command-line-overrides>
           for more information.

       -C PATH
           Changes the current working directory before executing any specified
           operations. This affects things like where cargo looks by default
           for the project manifest (Cargo.toml), as well as the directories
           searched for discovering .cargo/config.toml, for example. This
           option must appear before the command name, for example cargo -C
           path/to/my-project build.

           This option is only available on the nightly channel
           <https://doc.rust-lang.org/book/appendix-07-nightly-rust.html> and
           requires the -Z unstable-options flag to enable (see #10098
           <https://github.com/rust-lang/cargo/issues/10098>).

       -h, --help
           Prints help information.

       -Z flag
           Unstable (nightly-only) flags to Cargo. Run cargo -Z help for
           details.

   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.

       -j N, --jobs N
           Number of parallel jobs to run. May also be specified with the
           build.jobs config value
           <https://doc.rust-lang.org/cargo/reference/config.html>. Defaults to
           the number of logical CPUs. If negative, it sets the maximum number
           of parallel jobs to the number of logical CPUs plus provided value.
           If a string default is provided, it sets the value back to defaults.
           Should not be 0.

       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
       <https://doc.rust-lang.org/cargo/reference/environment-variables.html>
       for details on environment variables that Cargo reads.

EXIT STATUS
       o  0: Cargo succeeded.

       o  101: Cargo failed to complete.

EXAMPLES
       1. Build and execute all the benchmarks of the current package:

              cargo bench

       2. Run only a specific benchmark within a specific benchmark target:

              cargo bench --bench bench_name -- modname::some_benchmark

SEE ALSO
       cargo(1), cargo-test(1)

