How to monitor what's using the GPU

Something very funny since I'm using my GPU for holiday mining. When I run calculation on Maple, my GPU falls dramatically. Which I find very odd. It shouldn't be like this at all - I have enough cores to and RAM to rum CPU calculation together with GPU one.
So anyway, here's how you find what's using your GPU:
$fuser -v /dev/nvidiactl
It shows just the ethminer for me. You can do also:
$fuser -v /dev/nvidia*
if you want to see all the nvidia stuff.

Some other useful commands (source):

lspci -vnnn | perl -lne 'print if /^\d+\:.+(\[\S+\:\S+\])/' | grep VGA

this shows which is your active VGA controller.
Other things:

nvidia-settings

doesn't appear to work on my system. Claims I don't have the nvidia xdriver.
This one:

sudo lshw -C display

shows the two controllers.
A very cool more complicated command:
sudo lspci  -v -s  $(sudo lspci | grep ' VGA ' | cut -d" " -f 1)
will give you a lot  of info on your main VGA.
I think I have mentioned here already the
$nvidia-smi
A cool thing is also to use Chrome and about:gpu where you can find all kinds of info.