View Full Version : How many CUDA registers uses an OpenCL kernel

08-11-2009, 10:34 AM
Hello, I need to know how many registers my OpenCL kernel uses. I am down to executing the kernel in blocks with dimensions 2x4, which is too small to have a practical value. I have written CUDA equvalent of my kernel and it is able to run in blocksize of 8x32.

08-11-2009, 04:06 PM
Use clGetKernelWorkGroupInfo(kernel, CL_KERNEL_WORK_GROUP_SIZE, ..) to determine the max. work-group size that can be used for kernel.

08-12-2009, 06:55 AM
I have exported the kernel's intermediate PTX code into a text file, and then used the ptxas.exe to compile it in verbose mode. This yielded what I needed to know, in term of registers usage. Well, I need to know how to limit the registers, i.e. something similar to "--maxrregcount" as the ptxas option. Any ideas someone?

08-12-2009, 11:47 AM
you can try to use the compilation parameters you can set with opencl.

but in experienced that the parameters don't work with the first 2 releases (maybe it works with the conformant release).
i prefer to wait for the optimized version of the nvidia opencl release.

08-13-2009, 06:50 AM
I have no idea where to look for the vendor-specific compiler options. I have tried --help, but the program throws me out without the chance of debugging. I have tried "--maxrregcount" in addition to the clBuildProgram(..) build options, but the program throws me out again.