  We introduce an extremely computation-efficient CNN architecture named
ShuffleNet, which is designed specially for mobile devices with very limited
computing power (e.g., 10-150 MFLOPs). The new architecture utilizes two new
operations, pointwise group convolution and channel shuffle, to greatly reduce
computation cost while maintaining accuracy. Experiments on ImageNet
classification and MS COCO object detection demonstrate the superior
performance of ShuffleNet over other structures, e.g. lower top-1 error
(absolute 7.8%) than recent MobileNet on ImageNet classification task, under
the computation budget of 40 MFLOPs. On an ARM-based mobile device, ShuffleNet
achieves ~13x actual speedup over AlexNet while maintaining comparable
accuracy.
