[ViennaCL-devel] Other BLAS backends

[Karl R. <ru...@iu...>]

Hi Alex,

I've spent some more thoughts on how to separate the linear algebra 
backends suitably. Currently, some OpenCL statements are mixed into the 
vector<> and matrix<> classes, while the operations are clearly 
separated via calls to externally defined functions (e.g. prod_impl()), 
cf. vector_operations.hpp and matrix_operations.hpp.

To simplify your development efforts I could continue this separation 
and also move initialization routines to separate header files. In the 
best case, all that is necessary for a CPU-only fallback is to have e.g. 
in vector.hpp something like

#ifdef VIENNACL_NO_OPENCL
  #include "viennacl/linalg/vector-operations-cpu.hpp"
#else
  #include "viennacl/linalg/vector-operations-opencl.hpp"
#endif

Going one step further, we could even separate the convenience types 
from the BLAS backend and support something like

#if defined VIENNACL_USE_SSE_BLAS
  #include "viennacl/linalg/vector-operations-sse.hpp"
#elif defined VIENNACL_USE_OPENCL_BLAS
  #include "viennacl/linalg/vector-operations-opencl.hpp"
#elif defined VIENNACL_USE_OPENMP_BLAS
  #include "viennacl/linalg/vector-operations-openmp.hpp"
...
#else
  #include "viennacl/linalg/vector-operations-fallback.hpp"
#endif

We probably won't have the development resources for supporting a whole 
zoo of different backends, yet I like the idea of a clean separation. 
What do you think?

Best regards,
Karli

PS: cc'ed to viennacl-devel




On 07/29/2012 06:49 AM, Alex Christensen wrote:
> I made tred2 not copy memory, and it works with ublas matrices.  My goal
> is to make a backend so that defining VIENNACL_NO_OPENCL makes existing
> code work without a gpu (or even linking to an OpenCL library).  I'll
> let you know if I run into any problems.  Hopefully the existing QR code
> will work with that.
>
> Since the LU routines don't do partial pivoting, should I include my cpu
> LU function with partial pivoting?  Should I include my cholesky
> function also, maybe as a separate header?  The only cholesky function I
> have found in ViennaCL is in spai.
>
> Alex
>