[Octave-bug-tracker] [bug #46830] Multiplication about 4x slower than Matlab

[Armin Müller]

Follow-up Comment #7, bug #46830 (project octave):

Another benchmark:

Windows 7, 64 bit, i7-2620M (2 cores, 4 threads)

Octave 4.2.0, 32 bit

        a = rand (6000);
        tic; a * a; toc
        Elapsed time is 21.4271 seconds.

utilizing 4 threads

        a = rand (6000);
        tic; a .* a; toc
        Elapsed time is 0.116012 seconds.

utilizing 1 thread


Matlab R2015b, 64bit

        a = rand (6000);
        tic; a * a; toc
        Elapsed time is 13.481621 seconds.

utilizing 2 threads

        a = rand (6000);
        tic; a .* a; toc
        Elapsed time is 0.097478 seconds.

utilizing 2 threads


So, for me:
1) Both Octave and Matlab use parallelization, to a greater or lesser extent
2) Octave eats +50% runtime and +100% resources when multiplying matrices. =>
Maybe here, some improvement might be achieved be means of using other library
functions, but not "4x slower" as the ticket is saying.
3) When doing element-wise multiplication, both are on a par with runtime and
Octave is saving resources. This seems to be consistent with the reports of
Philip and Marco.
4) No clue about the GPU
Also, it may be that a bigger difference can be seen when using 6 CPU cores
(as Ceral has reported) as compared to 2 CPU cores on my machine. A benchmark
with varying the number of available CPU cores might be helpful.

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