Hi Vaclav, what I did is just removed flags "-DEIGEN_DONT_VECTORIZE -DEIGEN_DONT_ALIGN -DEIGEN_DISABLE_UNALIGNED_ARRAY_ASSERT" for some builds. I had a couple of strange crashes somewhere in quaternion-calculation, but now it seems OK. The speedup, which I measured was only about 2%, so I am not sure, that it gives a positive effect. So, from my point of view the vectorization in Yade code at the moment is useless.
2014-07-30 8:58 GMT+02:00 Václav Šmilauer <[email protected]>: > 1. supporting aligned types with boost::python (in minieigen) is hard or > impossible, see http://lists.boost.org/boost-users/2008/04/35638.php , > http://stackoverflow.com/questions/17364949/make-boostpython-respect-data-alignment> > , > http://stackoverflow.com/questions/13177573/how-to-expose-aligned-class-with-boost-python > . But actually there seems to be no definitive statement that it is "not > supported" and perhaps boost::python does the right thing automatically and > problems come from elsewhere. I contacted the authors of boost::python > directly to clarify that, there was no reaction. > > 2. All libraries MUST be compiled with EIGEN_NO_ALIGN or without it, mixing > those will lead to crashes (packet instruction on unaligned address, leads > to SIGFPU or SIGSEGV or SIGILL - don't remember anymore) I see. We mostly use minieigen (without vectorization) from packages and do not link minieigen directly to libyade. It seems, there are no crashes at least. > 3. Vectorization is only meaningful when compiling for targets supporting > packet instructions from the SSE2 set (IIRC) and higher. Compiling with > -march=i686 (which is what debian packages do by default) will probably > produce functioning builds, but they will effectively have no vectorization. > For that, -march=native (or something higher than i686 in general) is > needed. AFAIK (and according to Eigen3 FAQ) SSE2 instructions are enabled for x86-64 archs by default [1]. Not sure about Debian. -march is not in default flags either. Default flags, used for Debian packages are the following: dpkg-buildflags --get CXXFLAGS -g -O2 -fstack-protector --param=ssp-buffer-size=4 -Wformat -Werror=format-security Maybe there are some "hidden" flags for each particular arch. So, generally, I think the code should be adopted to use vectorization (large matrices, simple operations with them etc.). Just enabling it, does not give any visible benefit. [1] http://eigen.tuxfamily.org/index.php?title=FAQ#How_can_I_enable_vectorization.3F Cheers Anton _______________________________________________ Mailing list: https://launchpad.net/~yade-dev Post to : [email protected] Unsubscribe : https://launchpad.net/~yade-dev More help : https://help.launchpad.net/ListHelp
