How to get workload

You can find gpu info at /sys/devices/platform/*.gpu
'cat utilisation' then you can get gpu workload.

How to stress test the GPU

The mali GPU support only openGLES. So we have to use glmark2-es2 to do stress test. glmark2 is opengl application, glmark2-es2 is EGL/opengles application.
Use below command to do the test

glmark2-es2 --off-screen

or
glmark2-es2 --benchmark refract --run-forever --off-screen

If gpu usage not got to 90~100%, maybe the test case limited by cpu or some other things.
So you'd better increase cpu freq and ddr freq when test gpu performance.