0
Not a bug

R2018a_update3 (Linux) slow down MCT fft related functions

Michal Kvasnicka 6 months ago • updated 6 months ago 8

After installation of R2018a_update3 (Ubuntu 16.04 64 bit) was observed significant slow down of some MCT built-in functions (especially fft, ifft,fft2 and ifft2).

Answer

Answer

I see, thank you for clarification.  MATLAB is huge, maybe something went wrong during update.

But definitely, this it is not a toolbox bug :).

When re-apply all 3 available R2018a updates the situation is again normal ... now significant slow-down. Strange!!!???

Under review

I am not sure why this is happening.

But I suspect that freshly installed MATLAB might do some extra work in the background (building cache to speed-up startup time in future, or something similar). Do you see intensive processes in the background?

I have Matlab R2018a + update 2 working well with MTC. After install of R2018a_update3 I have got the above mentioned problem even after restart and Matlab warm up, so the cache should be already build. Then I reinstall all updates 1 + 2 + 3 again over this current Matlab installation and then everything works very well again.

Answer

I see, thank you for clarification.  MATLAB is huge, maybe something went wrong during update.

But definitely, this it is not a toolbox bug :).

OK ... I am happy now :)


Just one observation: during this problem all cores (+ logical threads) were fully used when MCT fft related (fft, ifft, fft2, ifft2) functions was tested by mp.Test. But these functions was terribly slow (~100x slow down).

Yes, these functions try to use all available cores. If functions were slow - this means that other processes were intensively using the same cores.

This is what is the really strange ... there were no additional processes just MATLAB.


I think we can forget this strange episode ...