Is MEX known to be slow on macOS?

Question: Is MEX known to be slow on macOS?

Here, "slow" refers to the speed of setting MEX up, of compiling MEX code, and of running the MEX function.

I have done some timing using GitHub Actions. The hardware specification is as follows. It is copied from the official documentation of GitHub Actions. The detailed information of CPU (frequency etc) and memory is not available.

GNU/Linux (ubuntu 20.04) and Windows (Windows Server 2019):

• 2-core CPU
• 7 GB of RAM memory
• 14 GB of SSD disk space

macOS (macOS Big Sur 11):

• 3-core CPU
• 14 GB of RAM memory
• 14 GB of SSD disk space

Here is the data obtained.

System: GNU/Linux | Language: C | MATLAB: 2021b | Time: 2022.02.26 05:46:36
MEX configured to use 'gcc' for C language compilation.
- Time for setting MEX up: 0.477950 seconds
- Time for mexifying timestwo: 4.500026 seconds
- Time for 100 runs of timestwo: 0.003845 seconds

System: Windows | Language: C | MATLAB: 2021b | Time: 2022.02.26 05:47:56
MEX configured to use 'Microsoft Visual C++ 2019 (C)' for C language compilation.
- Time for setting MEX up: 2.518557 seconds
- Time for mexifying timestwo: 4.416958 seconds
- Time for 100 runs of timestwo: 0.004215 seconds

System: macOS | Language: C | MATLAB: 2021b | Time: 2022.02.26 05:49:01
MEX configured to use 'Xcode with Clang' for C language compilation.
- Time for setting MEX up: 17.602277 seconds
- Time for mexifying timestwo: 5.979585 seconds
- Time for 100 runs of timestwo: 0.130843 seconds


System: GNU/Linux | Language: Fortran | MATLAB: 2021b | Time: 2022.02.26 05:46:20
MEX configured to use 'gfortran' for FORTRAN language compilation.
- Time for setting MEX up: 0.835881 seconds
- Time for mexifying timestwo: 2.768746 seconds
- Time for 100 runs of timestwo: 0.003279 seconds

System: Windows | Language: Fortran | MATLAB: 2021b | Time: 2022.02.26 05:51:04
MEX configured to use 'Intel oneAPI 2021 for Fortran with Microsoft Visual Studio 2019' for FORTRAN language compilation.
- Time for setting MEX up: 1.660305 seconds
- Time for mexifying timestwo: 3.495534 seconds
- Time for 100 runs of timestwo: 0.003299 seconds

System: macOS | Language: Fortran | MATLAB: 2021b | Time: 2022.02.26 05:49:47
MEX configured to use 'Intel Fortran Composer XE' for FORTRAN language compilation.
- Time for setting MEX up: 248.263933 seconds
- Time for mexifying timestwo: 87.093711 seconds
- Time for 100 runs of timestwo: 0.078741 seconds

It turns out that MEX is much slower on macOS than on GNU/Linux or Windows: slow to set up, slow to mexify, and the MEX function is slow to run. In particular, it is about 300 times slower to set up MEX for Fortran on macOS than on Linux. However, note that the significant difference probably comes from the virtual environment of GitHub Actions. On local machines, the difference may not be that dramatic.

If you are interested in the timing, below is the code I used for it. It is also available on GitHub.

function mex_time(language)
% MEX_TIME measures the running time of MATLAB concerning MEX. 

orig_warning_state = warning;
warning('off','all');

if nargin == 1 && (isa(language, 'char') || isa(language, 'string')) && strcmpi(language, 'Fortran')
    language = 'Fortran';
    timestwo_src = 'timestwo.F';
else
    language = 'C';
    timestwo_src = 'timestwo.c';
end

if ismac
    sys = 'macOS';
elseif isunix
    sys = 'GNU/Linux';
elseif ispc
    sys = 'Windows';
else
    error('Platform not supported.')
end

matlab_version = version('-release');
date_time = datestr(now,'yyyy.mm.dd HH:MM:SS');

fprintf('\nSystem: %s | Language: %s | MATLAB: %s | Time: %s\n\n', sys, language, matlab_version, date_time);

tic;
mex('-setup', language);
fprintf('\n- Time for setting MEX up: %f seconds\n\n', toc);

clear('timestwo');
tic;
mex(fullfile(matlabroot, 'extern', 'examples', 'refbook', timestwo_src));
fprintf('\n- Time for mexifying timestwo: %f seconds\n', toc);

tic;
for i = 1 : 100
    timestwo(i);
end
fprintf('\n- Time for 100 runs of timestwo: %f seconds\n\n', toc);
delete('timestwo.*');

warning(orig_warning_state);

You may try

mex_time('C');
mex_time('Fortran'); 

on you computer and post the results here. Thank you very much.

(See the discussions on StackOverflow and GitHub)