CARGO-BENCH(1)		    General Commands Manual		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
	  <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:

       •   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
       <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 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 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/reference/build-cache.html>
	   documentation for more details.

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

       --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:

	   •   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.

	   •   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:

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

	   •   always: Always display colors.

	   •   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:

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

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

	   •   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.

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

	   •   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.

	   •   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.

       --ignore-rust-version
	   Ignore rust-version specification in packages.

       --locked
	   Asserts that the exact same dependencies and versions are used as
	   when the existing Cargo.lock file was originally generated. Cargo
	   will exit with an error when either of the following scenarios
	   arises:

	   •   The lock file is missing.

	   •   Cargo attempted to change the lock file due to a different
	       dependency resolution.

	   It may be used in environments where deterministic builds are
	   desired, such as in CI pipelines.

       --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>.

       --frozen
	   Equivalent to specifying both --locked and --offline.

       --lockfile-path PATH
	   Changes the path of the lockfile from the default
	   (<workspace_root>/Cargo.lock) to PATH. PATH must end with
	   Cargo.lock (e.g. --lockfile-path
	   /tmp/temporary-lockfile/Cargo.lock). Note that providing
	   --lockfile-path will ignore existing lockfile at the default path,
	   and instead will either use the lockfile from PATH, or write a new
	   lockfile into the provided PATH if it doesn’t exist.	 This flag can
	   be used to run most commands in read-only directories, writing
	   lockfile into the provided PATH.

	   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 #14421
	   <https://github.com/rust-lang/cargo/issues/14421>).

   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
       •   0: Cargo succeeded.

       •   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)

								CARGO-BENCH(1)