CentOS - May 2018 - CentOS 7.5 and GPU memory

Is there a way to "control" how much GPU memory the OS uses ?
Back on CentOS 7.4 it "seemed" to use less. I want / need to tell 7.5
to
use less.\ or no GPU memory.  I have a video application that needs more of
the GPU memory and not so much the OS taking that memory.

How do I do that?

Thanks,

Jerry