We're developing using openCL, and have one dev machine with an NVIDIA GTX 260, and another with an ATI 4870. These both seem to be mid-range cards, and are similarly priced.
However, I'm sorry to say we are getting approximately 5x the performance from the NVIDIA card, than from the ATI. We're using the same openCL kernel, and the SDKs of the respective companies - in the case of the ATI, Stream SDK 2.0 beta 4.
Is this performance gulf due to the early stage of ATI's OpenCL support? Is the implementation not well optimised yet? If so, how soon can we expect this gap to close? Or were we mistaken about the equivalence of the two cards?
To be honest, I was expecting more from the 4870 - certainly the specs seemed to imply it was fairly powerful - however, currently my CPU (core2 quad 2.4GHz) can outperform it by roughly a factor of two. Something definitely seems amiss!
Many thanks for any information