@hazelnot so, this games commonly follow a cadence more or less along these lines:
1. read input events from controller
2. update game state
3. render a new frame image
4. present the new frame to the display
steps 1 and 2 happen on the CPU. step three starts with a bunch of up front work on the CPU to schedule work on the GPU, and step 4 is usually initiated on the CPU before 3 finishes on the GPU and then some complicated stuff happens