futhark-bench

SYNOPSIS

futhark bench [options…] programs…

DESCRIPTION

This tool is the recommended way to benchmark Futhark programs. Programs are compiled using the specified backend (futhark c by default), then run a number of times for each test case, and the average runtime printed on standard output. Refer to futhark-test for information on how to format test data. A program will be ignored if it contains no data sets - it will not even be compiled.

If compilation of a program fails, then futhark bench will abort immediately. If execution of a test set fails, an error message will be printed and benchmarking will continue (and --json will write the file), but a non-zero exit code will be returned at the end.

OPTIONS

--backend=name

The backend used when compiling Futhark programs (without leading futhark, e.g. just opencl).

--concurrency=NUM

The number of benchmark programs to prepare concurrently. Defaults to the number of cores available. Prepare means to compile the benchmark, as well as generate any needed datasets. In some cases, this generation can take too much memory, in which case lowering --concurrency may help.

--entry-point=name

Only run entry points with this name.

--exclude-case=TAG

Do not run test cases that contain the given tag. Cases marked with “nobench” or “disable” are ignored by default.

--futhark=program

The program used to perform operations (eg. compilation). Defaults to the binary running futhark bench itself.

--ignore-files=REGEX

Ignore files whose path match the given regular expression.

--json=file

Write raw results in JSON format to the specified file.

--no-tuning

Do not look for tuning files.

--pass-option=opt

Pass an option to benchmark programs that are being run. For example, we might want to run OpenCL programs on a specific device:

futhark bench prog.fut --backend=opencl --pass-option=-dHawaii
--pass-compiler-option=opt

Pass an extra option to the compiler when compiling the programs.

--runner=program

If set to a non-empty string, compiled programs are not run directly, but instead the indicated program is run with its first argument being the path to the compiled Futhark program. This is useful for compilation targets that cannot be executed directly (as with futhark-pyopencl on some platforms), or when you wish to run the program on a remote machine.

--runs=count

The number of runs per data set.

--skip-compilation

Do not run the compiler, and instead assume that each benchmark program has already been compiled. Use with caution.

--timeout=seconds

If the runtime for a dataset exceeds this integral number of seconds, it is aborted. Note that the time is allotted not per run, but for all runs for a dataset. A twenty second limit for ten runs thus means each run has only two seconds (minus initialisation overhead).

A negative timeout means to wait indefinitely.

-v, --verbose

Print verbose information about what the benchmark is doing. Pass multiple times to increase the amount of information printed.

--tuning=EXTENSION

For each program being run, look for a tuning file with this extension, which is suffixed to the name of the program. For example, given --tuning=tuning (the default), the program foo.fut will be passed the tuning file foo.fut.tuning if it exists.

WHAT FUTHARK BENCH MEASURES

futhark bench measures the time it takes to run the given Futhark program by passing the -t FILE option to the generated program. See the man page for the specific compiler to see exactly what is measured.

EXAMPLES

The following program benchmarks how quickly we can sum arrays of different sizes:

-- How quickly can we reduce arrays?
--
-- ==
-- nobench input { 0i64 }
-- output { 0i64 }
-- input { 100i64 }
-- output { 4950i64 }
-- compiled input { 10000i64 }
-- output { 49995000i64 }
-- compiled input { 1000000i64 }
-- output { 499999500000i64 }

let main(n: i64): i64 =
  reduce (+) 0 (iota n)