fortran time measurement

compilers

compiler	version
Intel Parallel Studio XE Composer Edition for Fortran	17.0.4.210
PGI Visual Fortran for Windows	18.7
GNU gfortran	7.3.0 (for Ubuntu on WSL)

compiler options

compiler	options
Intel	/O2 /Qopenmp
PGI	-mp -fast -tp=px
GNU	-fopenmp -Ofast

results

compiler	subroutine	execution time [s] 1 thread	2 threads	4 threads
Intel	system_clock	0.113	0.069	0.048
	cpu_time	0.109	0.115	0.109
	date_and_time	0.114	0.060	0.029
	omp_get_wtime	0.112	0.057	0.027
PGI	system_clock	0.112	0.063	0.050
	cpu_time	0.111	0.057	0.028
	date_and_time	0.112	0.057	0.028
	omp_get_wtime	0.111	0.057	0.028
GNU	system_clock	0.113	0.063	0.045
	cpu_time	0.109	0.094	0.031
	date_and_time	0.113	0.058	0.029
	omp_get_wtime	0.113	0.057	0.028

using QueryPerformanceCounter on Windows

compiler

compiler	version
Intel OneAPI	2021.1

compiler options

/O2 /Qopenmp /fpp

interface

    interface
        !! get the current value of the performance counter.
        function QueryPerformanceCounter(lPerformanceCount_count) result(is_succeeded) &
                                                                  bind(c, name="QueryPerformanceCounter")
            use, intrinsic :: iso_c_binding
            implicit none
            integer(c_long_long) :: lPerformanceCount_count
                !! current performance-counter value [count]
            logical(c_bool) :: is_succeeded
                !! nonzero (i.e. .true.) if the function succeeds
        end function QueryPerformanceCounter

        !! get the frequency of the performance counter.
        function QueryPerformanceFrequency(lFrequency_countPerSec) result(is_supported) &
                                                                   bind(c, name="QueryPerformanceFrequency")
            use, intrinsic :: iso_c_binding
            implicit none
            integer(c_long_long) :: lFrequency_countPerSec
                !! current performance-counter frequency [count/sec]<br>
                !! nonzero if the hardware running the program supports a high-resolution performance counter.
            logical(c_bool) :: is_supported
                !! nonzero (i.e. .true.) if the hardware supports a high-resolution performance counter
        end function QueryPerformanceFrequency
    end interface

results

The benchmark was run on a computer different from the one that ran the benchmark in the table above.

average

subroutine	execution time [s] 1 thread	2 threads	4 threads
system_clock	0.1206000	0.0668000	0.0486000
cpu_time	0.1250000	0.1218750	0.1156250
date_and_time	0.1228000	0.0636000	0.0312000
omp_get_wtime	0.1215305	0.0630220	0.0306592
QueryPerformanceCounter	0.1225477	0.0632070	0.0307012

run 1

subroutine	execution time [s] 1 thread	2 threads	4 threads
system_clock	0.1210000	0.0670000	0.0580000
cpu_time	0.1250000	0.1250000	0.1093750
date_and_time	0.1230000	0.0640000	0.0310000
omp_get_wtime	0.1207541	0.0637126	0.0313544
QueryPerformanceCounter	0.1213031	0.0639479	0.0307539

run 2

subroutine	execution time [s] 1 thread	2 threads	4 threads
system_clock	0.1210000	0.0670000	0.0460000
cpu_time	0.1250000	0.1093750	0.1250000
date_and_time	0.1230000	0.0640000	0.0300000
omp_get_wtime	0.1218192	0.0626389	0.0303834
QueryPerformanceCounter	0.1245900	0.0634314	0.0321276

run 3

subroutine	execution time [s] 1 thread	2 threads	4 threads
system_clock	0.1210000	0.0670000	0.0470000
cpu_time	0.1250000	0.1250000	0.1093750
date_and_time	0.1210000	0.0630000	0.0310000
omp_get_wtime	0.1215437	0.0627777	0.0300892
QueryPerformanceCounter	0.1215240	0.0620971	0.0307394

run 4

subroutine	execution time [s] 1 thread	2 threads	4 threads
system_clock	0.1200000	0.0660000	0.0460000
cpu_time	0.1250000	0.1250000	0.1250000
date_and_time	0.1230000	0.0630000	0.0310000
omp_get_wtime	0.1217981	0.0629676	0.0299242
QueryPerformanceCounter	0.1223847	0.0627128	0.0300906

run 5

subroutine	execution time [s] 1 thread	2 threads	4 threads
system_clock	0.1200000	0.0670000	0.0460000
cpu_time	0.1250000	0.1250000	0.1093750
date_and_time	0.1240000	0.0640000	0.0310000
omp_get_wtime	0.1217372	0.0630133	0.0298754
QueryPerformanceCounter	0.1229365	0.0638458	0.0297715