Microarchitectural Simulation and Control of di/dt-induced Power Supply Voltage Variation

As the power consumption of modern highperformance microprocessors increases beyond 100W, power becomes an increasingly important design consideration. This paper presents a novel technique to simulate power supply voltage variation as a result of varying activity levels within the microprocessor when executing typical software. The voltage simulation capability may be added to existing microarchitecture simulators that determine the activities of each functional block on a clock-by-clock basis. We then discuss how the same technique can be implemented in logic on the microprocessor die to enable real-time computation of current consumption and power supply voltage. When used in a feedback loop, this logic makes it possible to control the microprocessor's activities to reduce demands on the power delivery system. With on-die voltage computation and di/dt control, we show that a significant reduction in power supply voltage variation may be achieved with little performance loss or average power increase.