Fine-grained on-line power monitoring for soft microprocessor based system-on-chip

Today's CMOS technologies allow larger circuit designs to fit on a single chip. However, this advantage comes at a high price of increased process-voltage-temperature (PVT) variations. FPGAs and their designs are no exceptions to such variations. In fact, the same bit file loaded into two different FPGAs of the same model can produce a significant difference in power and thermal characteristics due to variations that exist within the chip. Since it is increasingly difficult to control physical variations through manufacturing tasks, there is a need for practical ways to sense chip variations to provide a way for circuit designers to compensate or avoid its negative effects. One of the most critical aspects of such variation is power. Therefore, we developed and demonstrated a high accuracy on-chip on-line Energy-per-Component (EPC) measurement technology on Xilinx FPGAs since 2011. However, we found that the hardware overhead associated with such method limited the use of the technology. Therefore, our follow-up work in Energy-per-Operation (EPO) on Spartan FPGA with OpenRISC SoC produced an equally accurate power monitoring technology with drastically lower hardware overhead. While this method made our technology more practical for SoC designs on FPGAs, it did not produce component level power dissipation data that previous EPC method provided. Therefore, we extend this prior work with a new algorithm to extract EPC values from EPO result. Despite the lower hardware overhead, this change ended up improving the accuracy of the power result by unraveling the instruction-level abstraction into component-level energy consumption.