Is it possible to switch between BLAS libraries without recompiling program?

Question

For example can I have Atlas, OpenBlas, MKL installed on my Ubuntu 14.04 at the same time and switch between them without recompiling Caffe?

Answer 1

You could also do it without changing system wide settings, for example by adding the library you want to use to the LD_PRELOAD or LD_LIBRARY_PATH environment variables. The first library on this path will be the one used to resolve the symbols against.

For example, you could run with

LD_PRELOAD=/path/to/blas/lib.so ./my_executable_using_caffe

You can see that this approach would be extremely useful as part of a benchmarking script for different implementations since it doesn't affect the benchmarking environment itself. For example (in bash):

my_libraries=/path/to/blas1.so /path/to/blas2.so

for lib in $my_libraries
do
  LD_PRELOAD=${lib} ./my_executable_using_caffe
done

This approach, based on dynamic linking, applies to any other shared library your program is compiled against.