On Mon, Feb 18, 2013 at 9:28 AM, Dag Sverre Seljebotn < d.s.seljeb...@astro.uio.no> wrote:
> 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. > For really small matrices, not using blas at all provides another speedup. Chuck > > 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 >
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