blas_lapack: add multithreading variant consistent in all implementations.

Question

build on Ubuntu 16 + gcc 5.4.0:

• [x] spack install openblas multithreading=none
• [x] spack install openblas multithreading=pthreads
• [x] spack install openblas multithreading=openmp
• [x] spack install atlas multithreading=none
• [x] spack install atlas multithreading=pthreads
• [x] spack install intel-mkl multithreading=none
• [x] spack install intel-mkl multithreading=openmp
• [x] spack install elemental

macOS Sierra + clang + gfortran: - [x] spack install openblas multithreading=none - [x] spack install openblas multithreading=pthreads - [x] spack install mumps+mpi ^intel-mkl ^mpich

in the later case for externally provided intel-mkl.0.128 in opt/intel we have:

LIBBLAS = -L/opt/intel/mkl/lib -L/usr/lib -lmkl_intel_lp64 -lmkl_core -lmkl_sequential -lpthread -lm -ldl
SCALAP = -L/opt/intel/mkl/lib -lmkl_scalapack_lp64 -lmkl_blacs_mpich_lp64

• [x] spack install dealii+mpi~sundials ^intel-mkl ^mpich

$ otool -L /Users/davydden/spack/opt/spack/darwin-sierra-x86_64/clang-8.1.0-apple/dealii-develop-n6julmgj2gj6twxodwe275zys4ily3fw/lib/libdeal_II.dylib  | grep "mkl"
    /libmkl_scalapack_lp64.dylib (compatibility version 0.0.0, current version 0.0.0)
    /libmkl_blacs_mpich_lp64.dylib (compatibility version 0.0.0, current version 0.0.0)
    /libmkl_intel_lp64.dylib (compatibility version 0.0.0, current version 0.0.0)
    /libmkl_core.dylib (compatibility version 0.0.0, current version 0.0.0)
    /libmkl_sequential.dylib (compatibility version 0.0.0, current version 0.0.0)

p.s. none value is there as we need at least two values.

fixes https://github.com/LLNL/spack/issues/1697

该提问来源于开源项目：spack/spack

Answer 1

while looking into PRs you might give a brief look at this one :smile:
I would like it to be merged in some near future as it fixes a bug where threaded openblas was used everywhere and could potentially lead to issues when downstream libraries use tbb. As an example, see dealii google forum.