  We introduce the family of limited model information control design methods,
which construct controllers by accessing the plant's model in a constrained
way, according to a given design graph. We investigate the closed-loop
performance achievable by such control design methods for fully-actuated
discrete-time linear time-invariant systems, under a separable quadratic cost.
We restrict our study to control design methods which produce structured static
state feedback controllers, where each subcontroller can at least access the
state measurements of those subsystems that affect its corresponding subsystem.
We compute the optimal control design strategy (in terms of the competitive
ratio and domination metrics) when the control designer has access to the local
model information and the global interconnection structure of the
plant-to-be-controlled. Lastly, we study the trade-off between the amount of
model information exploited by a control design method and the best closed-loop
performance (in terms of the competitive ratio) of controllers it can produce.
