[Numpy-discussion] [ANN] numscons 0.3.0 release
Thu Jan 24 22:03:10 CST 2008
Matthew Brett wrote:
> Hi David,
> Thanks again for doing this. I've been playing with the compilation -
> should I email you direct with questions, to the lists?
I don't think it would be inappropriate to use the current lists for that.
> Basically, I'm trying to understand the library discovery, linking
> steps - ATLAS in particular.
Don't trust the included doc: it is not up-to-date, and that's the part
which I totally redesigned since I wrote the initial doc.
For things like FFT, BLAS, LAPACK, things are a bit complicated.
Fortunately, for "normal" libraries, things are much easier: you use the
This function can check for a library, headers, and check for symbol in
the library. site.cfg customization is also automatically taken care of.
I also intend to add the possibility to check for libraries which use
For BLAS/LAPACK/FFT, the basic principles are:
- I make a distinction between "API libraries" (called meta
libraries in numscons) and "implementation libraries" (called perflib in
- Meta libraries uses perflibs: FFT/BLAS/LAPACK may use
- For each meta library and each perflib, a Check function is
defined: CheckMKL, CheckCBLAS, etc...
- For a perflib check to succeed, I try to compile, link and run
code snippets. Any failure means the Check* function will return failure.
- When a perflib Check* succeeds, the meta library check checks that
another code snippet can be compiled/linked/run. For example, if
CheckMKL succeeds in CheckCBLAS, I will compile/link/run a cblas program
using MKL configuration.
- Both perflib and meta libraries are customizable through site.cfg
(I tried to keep backward compatibility at this level with numpy.distutils).
I still have the feeling that it is over-designed, but BLAS/LAPACK
libraries are really a PITA. Every perflib has slightly different
conventions, and I wanted to use common code for all of them as much as
possible . Also, the configuration is not inside python code anymore:
libraries, frameworks, link flags are all defined in perflib.cfg.
 This design also allow some funky stuff: for example, when using sun
performance libraries with sun tools, because of something which look
like a bug to me, the sunperf are not linked when building a shared
library. So I link a code snippet, and parse the linker output to get
the necessary libraries; this is totally transparent to BLAS/LAPACK
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