With the holiday season in full swing, whether you are just a casual photographer or professional, Darktable is easily one of the best photography workflow applications and it's free software! Darktable has offered OpenCL acceleration for providing faster performance on GPUs and with the imminent Darktable 2.2 release there is even better OpenCL results. For those curious about the OpenCL performance of Darktable, I've done some Darktable 2.2-RC1 benchmarks on a variety of NVIDIA GeForce and AMD Radeon graphics cards under Ubuntu Linux.
The AMD cards tested for this comparison were using the AMDGPU-PRO 16.40 binary driver, which appeared to work fine with Darktable's OpenCL implementation. Tested cards included the Radeon R7 260X, R9 285, R9 290, RX 460, RX 470, RX 480, and R9 Fury. Unfortunately, no open-source results to share for this article due to the current Clover-based stack leaving a lot to be desired, but at least the new ROCm stack will be in better shape soon enough.
With the NVIDIA testing, the 375.10 driver was used and GeForce hardware tested included the GeForce GTX 680, GTX 780 Ti, GTX 950, GTX 960, GTX 970, GTX 980, GTX 980 Ti, GTX 1050, GTX 1050 Ti, GTX 1060, GTX 1070, and GTX 1080. There are more NVIDIA cards than AMD simply due to having more GeForce GPUs (thanks to NVIDIA for their review samples) and also the AMDGPU-PRO support currently being limited to GCN 1.1 and newer graphics processors. Besides the GPU benchmarks, a CPU-only run was also done with the Skylake Xeon v5 E3-1280 CPU too.