Re: LAPACK speed in Windows distribution

[Alexander Mamonov]

Hello Tatsuro,

I understand that performance of ATLAS depends greatly on the system
which was used to compile it. Since the Windows binary distributions
already ship with several different LAPACK libraries built for
different architectures, maybe it would make sense to add a little
code to the installer, that would test the performance of these
libraries (at the time of installation) to choose the one that gives
the optimal performance for a given machine?
Thank you for providing the build kit for MinGW users. May I suggest
that you expand the kit by including in it all dependencies required
to build Octave. This will provide a simple drop-in solution for
Windows users: install MinGW/MSYS -> add the kit -> build Octave. If
you think it's worth doing, I can provide you with a set of binaries
that I have built with octave-forge patches and scripts
(https://octave.svn.sourceforge.net/svnroot/octave/trunk/octave-forge/admin/Windows/mingw32/).

Regards,
Alex

2009/5/11 Tatsuro MATSUOKA <address@hidden>:
> Hello
>
> --- Alexander Mamonov wrote:
>
>> I have recently built Octave from recent sources with MinGW, and the
>> first thing I tried was
>> > tic; lu(rand(1000,1000)); toc;
>> For my build of Octave I compiled a plain vanilla unoptimized LAPACK
>> from netlib (LAPACK-lite), and the result of 0.5 sec versus M*lab's
>> 0.24 sec was not surprising to me. Then I compared it with Octave
>> 3.0.2 (MinGW) and 3.0.3 (VC) from octave-forge. Both were installed
>> with ATLAS chosen by the installer for my machine (SSE3 I believe). To
>> my astonishment both 3.0.2 and 3.0.3 have consistently shown a result
>> of 1.4sec. That's almost three times slower than the unoptimized (!)
>> LAPACK, and roughly six times slower than the result of the commercial
>> competitor.
>> I want Windows maintainers to be aware of this issue, so that some
>> improvements can be made in future versions.
>> Regards,
>>
>> Alex
> Speed on ATLAS strongly depend on the difference in CPU architecture and/or 
> code generated by the
> complier. I think it is very difficult problem to solve for generally 
> provided binaries.
>
> If you need higher performance for matrix, you should try to build ATLAS or 
> GotoBLAS by your computer
> and build octave on cygwin or MinGW.
>
> In my computer (HT^Pentium, prescott 3.4GHz ), I have got 4 times higher 
> Matrix calculation
> performance than that obtained octave 3.0.2 (MinGW).
>
> If you want to build octave from source, I have prepared library kit for 
> MinGW build.
>
> http://www.tatsuromatsuoka.com/octave/Eng/Win/index.html
>
> 0005 OctaveBuild.zip, 8,380,551 bytes, 2009-04-28, md5 
> 3587b65873be7d5e2b38a671162fa61e, octave build
> tool kit under the MinGW
> 0006 ReadmeBriefOctBuildMingw.html, 11,748 bytes, 2009-05-04, md5 
> 1a52737ad283dfd8178159edc1720dc3,
> Brief explanation for the octave build tool kit under the MinGW, plese read 
> this before use.
>
> Regards
>
> Tatsuro
>
>
>
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