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.
--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.
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.
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.
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.
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.
--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:
•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.
--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.
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-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>.
+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.
-h, --help
Prints help information.
-Z flag
Unstable (nightly-only) flags to Cargo. Run cargo -Z
help for details.
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. Should not be 0.
--keep-going
Build as many crates in the dependency graph as possible,
rather than aborting the build on the first one that fails to build. Unstable,
requires -Zunstable-options.