NVPROF on Jetson TK1: Kernel Time Fluctuation

Hi, I have this problem with a kernel profiling on a Jetson TK1. I have a C program that launches a kernel 30 times. With ssh I launch nvprof and the times returned are differents. Some times the avarege time of the 30 executions is 90 ms, other times is 24 ms or 15 ms. Why there is this fluctuation?

I fixed the GPU clock and I resolved