1. "Automatic graphics switching" needs to be turned off under system preferences>energy saver.
2. I believe to capture real GPU power usage at that point, we need to use BattOr rather than Intel MSRs.

From discussion on Mac GPU power test doc: https://docs.google.com/document/d/1FVwxT21R4p2EffmSlKtnOqfO_UE0VSKF-fvYUgtp08o/edit#heading=h.9izw1ok58jgj

Annie Sullivan	
"""
I just wanted to double-check this point: at Mac team's request we actually have ordered dual-GPU macs for deployment in the lab (alonside low-end macbook airs and the existing retina macbook pros). We don't do anything special to tell those machines which GPU to use. We still care about this config, right?
"""

Erik Chen
"""
To force discrete GPU, the setting "automatic graphics switching" under Settings>power needs to be disabled. Furthermore, I believe Intel MSRs won't capture the power usage of the discrete GPU, and that we have to use BattOrs. Do you want me to file a bug?
"""