// Call after picking out a frame, so 0 means starvation.
void update_policy(std::chrono::steady_clock::time_point now,
std::chrono::steady_clock::time_point expected_next_frame,
// Call after picking out a frame, so 0 means starvation.
void update_policy(std::chrono::steady_clock::time_point now,
std::chrono::steady_clock::time_point expected_next_frame,