On 30/01/14 21:37, Andreas Kloeckner wrote: > One thing that sort of killed sub-buffers for me as far as usefulness is > concerned is that they are allowed to have restrictive (and > platform-dependent!) alignment requirements, based on > cl.device_info.MEM_BASE_ADDR_ALIGN. On all the platforms where I > checked, that value is 1024 or 4096.
Yes, I was similarly disappointed by this requirement. Further, the spec also disallows creating sub-buffers of sub-buffers. This (almost certainly arbitrary) requirement requires extra bookkeeping on the part of application developers. (Whenever I make a sub-buffer I also need to retain a reference to the original buffer and the offset of the sub buffer.) Interestingly the NVIDIA OpenCL implementation allows one to forgo both of the above requirements. > Your offsets appear fine with respect to that, so I'm not sure what > you're up against here. Looks like an Nvidia bug from here... More than likely. My only thought is if pyopencl would be thrown by: "The implementation may return the same cl_mem object with the reference count incremented appropriately for multiple calls to clCreateSubBuffer that use the same values for buffer, flags, buffer_create_type and buffer_create_info points to the same descriptor or descriptors that describe values that are exactly the same." Regards, Freddie.
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