The relationship between ISP and GPU

Hi,ererybody

My customer sensor is ov4689.The sensor frame rate is 30fps.I have ported it to tx1’ISP. I capture camera’frame with tegra_multimedia_api.I have a program run on tx1’s GPU.

Then I found the time I read frames is not constant.When the load on GPU is high,the time read frames is long(about 110ms),but when the load is low,the time is short(about 40ms).

My question:
1.What 's the relationship between ISP and GPU ?
2.Is ISP part of GPU ?
3.Do ISP and GPU share part of the resources?

@CalmCar
ISP and GPU are two dependency HW. Your problem may relative to the APP that use the GPU for some image post processing and block the pipeline cause the frame drop.