futhark-bench [–runs=count | –compiler=program | –json | –no-validate] programs...


This program is used to benchmark Futhark programs. In addition to the notation used by futhark-test(1), this program also supports the dataset keyword nobench. This is used to indicate datasets that are worthwhile for testing, but too small to be worth benchmarking.

Programs are compiled using the specified compiler (futhark-c by default), then run a number of times for each data set, and the average runtime printed on standard output. A program will be ignored if it contains no data sets - it will not even be compiled. Only data sets that use the default entry point (main) are considered.

If compilation or running fails, an error message will be printed and benchmarking will continue, but a non-zero exit code will be returned at the end.


--runs=count The number of runs per data set.
 The program used to compile Futhark programs. This option can be passed multiple times, resulting in multiple compilers being used for each test case. The specified program must support the same interface as futhark-c.
--json=file Write raw results in JSON format to the specified file.

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 --compiler=futhark-opencl --pass-option=-dHawaii

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.


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

-- How quickly can we reduce arrays?
-- ==
-- nobench input { 0 }
-- output { 0 }
-- input { 100 }
-- output { 4950 }
-- compiled input { 100000 }
-- output { 704982704 }
-- compiled input { 100000000 }
-- output { 887459712 }

let main(n: i32): i32 =
  reduce (+) 0 (iota n)


futhark-c(1), futhark-test(1)