GPU EUs Active
The metric GPU EUs Active represents the percentage of time when the GPU execution units (EUs) were actively executing pixel, geometry, or vertex shader instructions.
If GPU EUs Active is 80 it means that EUs where active 80% of the rendering time for selected ergs.
If the EUs are not active, it means that they are either stalled waiting for a request to be fulfilled, or idle. You can see how much of the non-active time is caused by stalls by examining the GPU EUs Stalled metric. If the total EU busy time (GPU EUs Active + GPU EUs Stalled) is significantly lower than 100%, this indicates that there are stalls elsewhere in the rendering pipeline.