Voltage Noise in Production Processors

Abstract—Parameter variations have become a dominant challenge in microprocessor design. Voltage variation is especially daunting because it happens so rapidly. We measure and characterize voltage variation in a running Intel R￿ CoreTM 2 Duo processor. By sensing on-die voltage as the processor runs singlethreaded, multi-threaded, and multi-program workloads, we determine the average supply voltage swing of the processor to be only 4%, far from the processor’s 14% worst-case operating voltage margin. While such large margins guarantee correctness, they penalize performance and power efficiency. We investigate and quantify the benefits of designing a processor for typical-case (rather than worst-case) voltage swings, assuming that a fail-safe mechanism protects it from infrequently occurring large voltage fluctuations. With today’s processors, such resilient designs could yield 15% to 20% performance improvements. But we also show that in future systems, these gains could be ...

• Type: Journal
• Year: 2011
• Where: MICRO
• Authors: Vijay Janapa Reddi, Svilen Kanev, Wonyoung Kim, Simone Campanoni, Michael D. Smith, Gu-Yeon Wei, David Brooks
• Keywords: Guarantee Correctness, Hardware, MICRO 2011, Microprocessor Design, Voltage Swings