Before revision:  Finally we demonstrate a 6-18 \times speedup versus CPU in an X-ray diffraction 3D iterative reconstruction task at 10^{-12} accuracy, observing excellent multi-GPU weak scaling up to one rank per GPU.
After revision:  Finally we demonstrate a 5-12 \times speedup versus CPU in an X-ray diffraction 3D iterative reconstruction task at 10^{-12} accuracy, observing excellent multi-GPU weak scaling up to one rank per GPU.