Hi, I saw on the mailing list and in the NEWS file that some unsafe math transformations were disabled for the reference BLAS implementation that is used in R. We have a set of performance tests for the OpenMx library, and some of the tests have a x3-10 slowdown in R 2.12.0 versus 2.11.1. When I copy the shared library libRblas.0.dylib from the 2.11.1 installation into the 2.12.0 installation, the slowdown goes away. It seems reasonable that BLAS should conform to IEEE requirements. For the purposes of our library, we are considering two options but I need some advice on both choices:
1) Compile the reference BLAS implementation with unsafe optimizations and include it as a part of the OpenMx library. I can't seem to reproduce the speed of the 2.11.1 reference BLAS library. What compiler, which version of the compiler, and what flags are used when an R binary is distributed? My test machine is a Mac Pro, that may change the answer. 2) Is there any support for adding a libRblas.unsafe.dylib shared library in the R installation, much like libRblas.veclib.dylib is currently included in OS X binaries? Then we could just change the OpenMx shared library to use the unsafe library when we give it to users. We currently change the OpenMx shared library to use the reference blas implementation, because it is faster than the veclib implementation for small matrices. Thank you! --Michael
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