PyOpenCL FAQ [Edit]

General Questions [Edit]

Which implementations was PyOpenCL tested against? [Edit]

So far, the following:

• AMD Stream SDK 2.01

• Nvidia's OpenCL GPU driver

• Apple Snow Leopard

• Apple Lion

Should I use PyOpenCL or PyCUDA? [Edit]

Good question. I put together a page that presents arguments that help you decide. The answer will likely depend on your particular situation. In most cases, "it doesn't matter" is probably the correct answer.

Build Questions [Edit]

I get a compilation error with CUDA 3.2 [Edit]

Does your error look like this?

In file included from src/wrapper/wrap_cl.hpp:23,
                 from src/wrapper/wrap_cl.cpp:1:
/home/andreas/pool/cuda-3.2/include/CL/cl_ext.h:166: error: expected constructor, destructor, or type conversion before ‘!’ token
In file included from src/wrapper/wrap_cl.cpp:1:
src/wrapper/wrap_cl.hpp: In member function ‘boost::python::list pyopencl::device::create_sub_devices(boost::python::api::object)’:
src/wrapper/wrap_cl.hpp:549: error: ‘clCreateSubDevicesEXT_fn’ was not declared in this scope
src/wrapper/wrap_cl.hpp:549: error: expected ‘;’ before ‘cl_create_sub_devices’
src/wrapper/wrap_cl.hpp:553: error: ‘cl_create_sub_devices’ was not declared in this scope
src/wrapper/wrap_cl.hpp:564: error: ‘cl_create_sub_devices’ was not declared in this scope
src/wrapper/wrap_cl.hpp:570: error: ‘cl_create_sub_devices’ was not declared in this scope

If so, the problem is that Nvidia shipped a broken cl_ext.h header with CUDA 3.2. Upgrade to CUDA 4.0, or use the patch below to set things straight. If neither of these is an option, configure PyOpenCL with CL_ENABLE_DEVICE_FISSION = False.

--- CL/cl_ext.h     2011-04-24 00:17:26.479673000 -0400
+++ CL/cl_ext.h 2011-04-17 14:53:45.814178002 -0400
@@ -21,7 +21,7 @@
  * MATERIALS OR THE USE OR OTHER DEALINGS IN THE MATERIALS.
  ******************************************************************************/
 
-/* $Revision: 11687 $ on $Date: 2010-06-12 03:47:22 +0530 (Sat, 12 Jun 2010) $ */
+/* $Revision: 11928 $ on $Date: 2010-07-13 21:34:56 +0530 (Tue, 13 Jul 2010) $ */
 
 /* cl_ext.h contains OpenCL extensions which don't have external */
 /* (OpenGL, D3D) dependencies.                                   */
@@ -163,7 +163,7 @@
                             cl_device_id * /*out_devices*/,
                             cl_uint * /*num_devices*/ ) CL_EXT_SUFFIX__VERSION_1_1;
 
-    extern CL_API_ENTRY cl_int 
+    typedef CL_API_ENTRY cl_int 
     ( CL_API_CALL * clCreateSubDevicesEXT_fn)(  cl_device_id /*in_device*/,
                                                 const cl_device_partition_property_ext * /* properties */,
                                                 cl_uint /*num_entries*/,

Unfortunately, there isn't enough version information available in these headers to catch the problem ahead of time.

I have <insert random compilation problem> with gcc 4.1 or older. Help! [Edit]

Try adding:

CXXFLAGS = ['-DBOOST_PYTHON_NO_PY_SIGNATURES', '-DBOOST_NO_INCLASS_MEMBER_INITIALIZATION']

to your pyopencl/siteconf.py or $HOME/.aksetup-defaults.py.

Usage Questions [Edit]

Can I get syntax highlighting for CL code included in Python? [Edit]

Yes. In Vim, use the file contrib/pyopencl.vim and see the comments therein. (This file will be added in version 2011.1. You can alternatively get it from git)

Packing up parameters is getting tedious. Help? [Edit]

Check out Yapocis, by Sean True.