Cactus Code Thorn OpenCL
Author(s)    : Erik Schnetter
Maintainer(s): Cactus team
Licence      : GPL, public domain
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1. Purpose

Configure with OpenCL; see <http://www.khronos.org/opencl/>.



From the web site:

OpenCL - The open standard for parallel programming of heterogeneous
systems

OpenCL(TM) is the first open, royalty-free standard for
cross-platform, parallel programming of modern processors found in
personal computers, servers and handheld/embedded devices. OpenCL
(Open Computing Language) greatly improves speed and responsiveness
for a wide spectrum of applications in numerous market categories from
gaming and entertainment to scientific and medical software.



2. Available implementations

There seem to be four OpenCL implementations available at this time.
Unfortunately, they each have their drawbacks:

- AMD: Available at
  <http://developer.amd.com/zones/openclzone/pages/default.aspx>. This
  supports both CPUs and ATI GPUs. Unfortunately, the OpenCL compiler
  seems to produce code with a low quality.

- Apple: Included with the operating system, available by default.
  This supports both CPU and GPU. The compiler is based on LLVM.
  Unfortunately, there seem to be serious bugs -- for example, I can't
  get the cos function to provide correct results.

- FreeOCL: Open source, available at
  <https://code.google.com/p/freeocl/>. This is a stand-alone
  implementation for CPUs only.

- Intel: Available at
  <http://software.intel.com/en-us/articles/opencl-sdk/>. This
  supports only (Intel?) CPUs. The compiler is based on LLVM, and the
  implementation is also based on Intel's TBB (Threading Building
  Blocks).

- Nvidia: Available at <http://developer.nvidia.com/opencl>, included
  in their CUDA distribution. This supports only GPUs.

- pocl: Open source, available at <https://launchpad.net/pocl>. This
  OpenCL implementation is based on LLVM.

In addition, Wikipedia <http://en.wikipedia.org/wiki/OpenCL> lists two
IBM implementations for their Power processor and for Intel compatible
CPUs, respectively. The latter may be identical with or similar to
AMD's implementation.



3. Disassembling OpenCL code

Intel:

env PATH=$PATH:/usr/local/intel_ocl_sdk_1.5_x64/usr/lib64/OpenCL/vendors/intel CLASSPATH=/usr/local/intel_ocl_sdk_1.5_x64/usr/lib64/OpenCL/vendors/intel LD_LIBRARY_PATH=/usr/local/intel_ocl_sdk_1.5_x64/usr/lib64/OpenCL/vendors/intel /usr/local/intel_ocl_sdk_1.5_x64/usr/bin/ioc -input=mk-mclachlan-cl-rhs/ML_BSSN_CL_InitRHS.cl -asm=ML_BSSN_CL_InitRHS.cl.s