about GPU acceleration

Dear all,
I am running an MD simulation with lammps-17Nov16 under Linux peration system. The software was built with gpu package. When my model was discribed by a lj/cut/coul/cut potential, the GPU acceleration was effective. But when I used the lj/smooth/linear potential, there was almost no difference between using GPU or not. Besides, I have checked the GPU utilization with nvidia-smi command. It was always 0%.
May I have your suggestions? Many thanks for your reply.

Fan

There has to be a /gpu version of a pair style in order to have GPU acceleration.
If you use the -sf flag, LAMMPS will fall back to the CPU version, if no GPU version exists. For details please see the manual, which explains this and more in great detail.
Axel