MATLAB Answers

1

Best way to do memory testing?

Asked by Shaun VanWeelden on 31 Jan 2013
Accepted Answer by Jan
Hi,
My name is Shaun VanWeelden and I am working on a project to look at script performance. A large part of what I do is gather code to evaluate and see what errors are thrown, etc. I also try and do performance testing (using tic toc) and memory usage. We currently do memory testing the following way:
%Get initial memory being used
[user, sys] = memory ;
mStart = user.MemUsedMATLAB ;
%Get initial start time
tic
%Run the actual script, the 'evalc" suppresses all output,
%do "eval" without the c to see program output
evalc(the script);
%Figure out how long script took to run
time=toc;
%Calculate total memory used and add it to the cell array
[user, sys] = memory ;
mtotal = user.MemUsedMATLAB - mStart;
But this has provided very inconsistent results due to the large number of other things going on inside the testing script. I was wondering if there was a better way to get the individual scripts we are testing’s memory use.
Thank you and let me know if you have any additional questions!
-Shaun VanWeelden

  2 Comments

what does a typical "the script" look like?
Almost anything to be honest, lets just say if I wanted to run every product demo and evaluate it or something like that, it needs to be a pretty flexible program, whats your ideas? Even if it won't work completely with what I am trying to do

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3 Answers

Answer by Jan
on 31 Jan 2013
 Accepted Answer

A lot of important details of the memory usage cannot be measured by calling memory before and after calling a script or a function. Example:
function out = func1
out = rand(1000, 1000);
for ii = 1:numel(out)
out(ii) = sqrt(sin(abs(out(ii) - 1)));
end
end
function out = func2
tmp = rand(1000, 1000);
out = sqrt(sin(abs(tmp - 1)));
end

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Answer by Image Analyst
on 1 Feb 2013

Did you see the "profile" function in the help?

  1 Comment

Very helpful, thank you!

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Answer by Shashank Prasanna on 1 Feb 2013

Since we are talking undocumented, do check out feature('memstats') I am not sure how you will use this, but it gives a lot more information than memory does.

  1 Comment

Interesting to compare to structs returned by memory() ..
>> T = evalc('feature(''memstats'')') ;
>> str2mat(regexp(T, '(?<=Use:\s*)\d+', 'match'))

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