Showing papers by "Seokhyeong Kang published in 2010"
18 Jan 2010
TL;DR: This work proposes a design-level approach to trading off reliability and voltage (power) in, e.g., microprocessor designs through techniques for power-aware slack redistribution that shift the timing slack of frequently-exercised, near-critical timing paths in a power- and area-efficient manner.
Abstract: Modern digital IC designs have a critical operating point, or “wall of slack”, that limits voltage scaling. Even with an error-tolerance mechanism, scaling voltage below a critical voltage - so-called overscaling - results in more timing errors than can be effectively detected or corrected. This limits the effectiveness of voltage scaling in trading off system reliability and power. We propose a design-level approach to trading off reliability and voltage (power) in, e.g., microprocessor designs. We increase the range of voltage values at which the (timing) error rate is acceptable; we achieve this through techniques for power-aware slack redistribution that shift the timing slack of frequently-exercised, near-critical timing paths in a power- and area-efficient manner. The resulting designs heuristically minimize the voltage at which the maximum allowable error rate is encountered, thus minimizing power consumption for a prescribed maximum error rate and allowing the design to fail more gracefully. Compared with baseline designs, we achieve a maximum of 32.8% and an average of 12.5% power reduction at an error rate of 2%. The area overhead of our techniques, as evaluated through physical implementation (synthesis, placement and routing), is no more than 2.7%.
159 citations
01 Apr 2010
TL;DR: In this paper, the authors present a power-aware slack redistribution technique to increase the range of voltages over which the incidence of operational (timing) errors is acceptable for soft architectures.
Abstract: Current processor designs have a critical operating point that sets a hard limit on voltage scaling. Any scaling beyond the critical voltage results in exceeding the maximum allowable error rate, i.e., there are more timing errors than can be effectively and gainfully detected or corrected by an error-tolerance mechanism. This limits the effectiveness of voltage scaling as a knob for reliability/power tradeoffs. In this paper, we present power-aware slack redistribution, a novel design-level approach to allow voltage/reliability tradeoffs in processors. Techniques based on power-aware slack redistribution reapportion timing slack of the frequently-occurring, near-critical timing paths of a processor in a power- and area-efficient manner, such that we increase the range of voltages over which the incidence of operational (timing) errors is acceptable. This results in soft architectures — designs that fail gracefully, allowing us to perform reliability/power tradeoffs by reducing voltage up to the point that produces maximum allowable errors for our application. The goal of our optimization is to minimize the voltage at which a soft architecture encounters the maximum allowable error rate, thus maximizing the range over which voltage scaling is possible and minimizing power consumption for a given error rate. Our experiments demonstrate 23% power savings over the baseline design at an error rate of 1%. Observed power reductions are 29%, 29%, 19%, and 20% for error rates of 2%, 4%, 8%, and 16% respectively. Benefits are higher in the face of error recovery using Razor. Area overhead of our techniques is up to 2.7%.
88 citations
13 Jun 2010
TL;DR: It is shown that significant power benefits are possible from a recovery-driven design flow that deliberately allows errors caused by voltage overscaling to occur during nominal operation, while relying on an error recovery technique to tolerate these errors.
Abstract: Conventional CAD methodologies optimize a processor module for correct operation, and prohibit timing violations during nominal operation. In this paper, we propose recovery-driven design, a design approach that optimizes a processor module for a target timing error rate instead of correct operation. We show that significant power benefits are possible from a recovery-driven design flow that deliberately allows errors caused by voltage overscaling ([10],[3]) to occur during nominal operation, while relying on an error recovery technique to tolerate these errors. We present a detailed evaluation and analysis of such a CAD methodology that minimizes the power of a processor module for a target error rate. We demonstrate power benefits of up to 25%, 19%, 22%, 24%, 20%, 28%, and 20% versus traditional P&R at error rates of 0.125%, 0.25%, 0.5%, 1%, 2%, 4%, and 8%, respectively. Coupling recovery-driven design with an error recovery technique enables increased efficiency and additional power savings.
43 citations
22 Mar 2010
TL;DR: This work states that timing exceptions in IC implementation processes help reduce pessimism that arises from unnecessary timing constraints by masking non-functional critical paths and expects this positive impact since timing exceptions reduce the number of constraints that the design optimization must satisfy.
Abstract: Timing exceptions in IC implementation processes, especially timing verification, help reduce pessimism that arises from unnecessary timing constraints by masking non-functional critical paths. Ideally, timing exceptions should always be helpful for quality of results (QOR) metrics such as area or number of timing violations, and for design turnaround time (TAT) metrics such as tool runtime and number of design iterations.We expect this positive impact since timing exceptions reduce the number of constraints that the design optimization must satisfy.