FFT bench on Linux machine

I have Intel i7 4790k and MATLAB 2015a on Windows 7 SP1. The bench for this configuration: 0.1366 0.0575 0.0412 0.0883 0.3454 0.4137

I installed Linux Gentoo and MATLAB 2016a on this machine yesterday. And bench: 0.1612 0.1028 0.0639 0.0745 0.4773 0.3888

Why fft is slowly in 2 times? It it a bug at compiling FFTW library for Linux in MATLAB? Or bench is not intended to compare two different versions of MATLAB?

Answer 1

[Steven Lord]

Do not use different releases' version of bench to perform comparisons. I believe there is a note to that effect at the bottom of the results figure (unless someone removed it recently.)

If you absolutely must use bench to compare two releases run the older release's version of bench on both. But in this scenario, you're comparing oranges and grapefruit, since you're changing operating systems. They're both citrus fruits, but if you hand me a glass of grapefruit juice instead of orange juice I will notice it at first sip.

[Viacheslav Klimentyev]

Thanks for your response! I found a solution for compare two different versions. I opened bench.m and analyzed code. In 2015b fft size is 2^22 and in 2016a it is 2^23, i.e. bench results are correct.

[Steven Lord]

Yes. Changes to the bench problem sizes are one of the reasons why we tell people not to compare bench results across releases.