On 02/18/2013 05:26 PM, rif wrote: > I have no answer to the question, but I was curious as to why directly > calling the cblas would be 10x-20x slower in the first place. That > seems surprising, although I'm just learning about python numerics.
The statement was that directly (on the Cython level) calling cblas is 10x-20x slower than going through the (slow) SciPy wrapper routines. That makes a lot of sense if the matrices are smalle nough. Dag Sverre > > > On Mon, Feb 18, 2013 at 7:38 AM, Sergio Callegari > <sergio.calleg...@gmail.com <mailto:sergio.calleg...@gmail.com>> wrote: > > Hi, > > I have a project that includes a cython script which in turn does > some direct > access to a couple of cblas functions. This is necessary, since some > matrix > multiplications need to be done inside a tight loop that gets called > thousands > of times. Speedup wrt calling scipy.linalg.blas.cblas routines is > 10x to 20x. > > Now, all this is very nice on linux where the setup script can > assure that the > cython code gets linked with the atlas dynamic library, which is the > same > library that numpy and scipy link to on this platform. > > However, I now have trouble in providing easy ways to use my project in > windows. All the free windows distros for scientific python that I have > looked at (python(x,y) and winpython) seem to repackage the windows > version of > numpy/scipy as it is built in the numpy/scipy development sites. > These appear > to statically link atlas inside some pyd files. So I get no atlas > to link > against, and I have to ship an additional pre-built atlas with my > project. > > All this seems somehow inconvenient. > > In the end, when my code runs, due to static linking I get 3 > replicas of 2 > slightly different atlas libs in memory. One coming with > _dotblas.pyd in numpy, > another one with cblas.pyd or fblas.pyd in scipy. And the last one > as the one > shipped in my code. > > Would it be possible to have a win distro of scipy which provides some > pre built atlas dlls, and to have numpy and scipy dynamically link > to them? > This would save memory and also provide a decent blas to link to for > things > done in cython. But I believe there must be some problem since the > scipy site > says > > "IMPORTANT: NumPy and SciPy in Windows can currently only make use > of CBLAS and > LAPACK as static libraries - DLLs are not supported." > > Can someone please explain why or link to an explanation? > > Unfortunately, not having a good, prebuilt and cheap blas > implementation in > windows is really striking me as a severe limitation, since you > loose the > ability to prototype in python/scipy and then move to C or Cython > the major > bottlenecks to achieve speed. > > Many thanks in advance! > > _______________________________________________ > NumPy-Discussion mailing list > NumPy-Discussion@scipy.org <mailto:NumPy-Discussion@scipy.org> > http://mail.scipy.org/mailman/listinfo/numpy-discussion > > > > > _______________________________________________ > NumPy-Discussion mailing list > NumPy-Discussion@scipy.org > http://mail.scipy.org/mailman/listinfo/numpy-discussion > _______________________________________________ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
