[Octave-bug-tracker] [bug #44703] 10X slowdown on Windows XP vs. Linux

[Philip Nienhuis]

Follow-up Comment #5, bug #44703 (project octave):

I'm also surprised, if not flabbergasted. 
Note that years ago, Octave on Linux also ran slower than on Windows and both
were slower than OS/2; I think OS/2 was twice as fast as Linux (AFAIU OS/2 in
its time had a superior threading model).
But yes 3 X slower is, well, ridiculous :-) - esp. as I ran the GUIs on
Windows and the CLI on Linux to avoid workspace pane updates.

I've built the Windows versions with MXE & OpenBLAS (cross-build;
--enable-windows-64); the Linux one (64-bit indexing) also with MXE (native
build) and (IIRC) OpenBLAS, with the configure options outlined by JWE in a
bug report from some months ago:

https://savannah.gnu.org/bugs/index.php?43319, see comment#13 there.

I also tried a "regular" Linux build with the 32-bit indexing libs supplied by
Mageia, without OpenBLAS; that had about the same execution time as the 64-bit
indexing Octave. So that may be a clue that OpenBLAS wasn't invoked on Linux.

I'm not very sure I've also specified the --enable-openblas option, but
OpenBLAS was built and in the .tgz, I figure just symlinking libblas.so to
libopenblas.so would suffice?

Just to be sure, in the Windows version I copied librefblas.dll to libblas.dll
and tried again:

>> tic; lintst; toc
100 / 100 passed
Elapsed time is 10.9646 seconds.
>>


...so it seems OpenBLAS or refBLAS don't make much difference.
There seems to be a lot of overhead elsewhere in Octave.

FWIW, my desktop system:
Gigabyte Z87-HD3 mobo, 8 GB RAM
Core i5-4570 3.2GHz
500 GB SSD
Windows 7 Prof. 64-bit  &  Mageia-4 Linux 64-bit


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