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http://www.cs.virginia.edu/~krw7c/avf.html Bit Read? Bit has error protectio n benign fault no error yes no Does bit matter? no Does bit matter? Particle Strike Causes Bit Flip! Detection only Detection & Correction benign fault no error benign fault no error Silent Data Corruption yes no True Detected Unrecoverabl e Error False Detected Unrecoverabl e Error yes no Outliers We identify strong correlations between structural AVF values and a small set of processor metrics. Using linear and quadratic regression, we came up with an AVF characterization that uses only a few variables. These characterizations can be used to predict AVF accurately! FIT = Failure in Time = 1 failure in a billion hours Intel Corporation 1 10 100 1000 10000 100000 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 D ata C orruption FIT 1000 M TBF G oal FIT ifallflips m anifestas errors FIT if10% offlips m anifestas errors •Transient faults due to particle strikes are a key challenge in microprocessor design. • As transistor counts increase exponentially, per-chip faults are a growing burden. • Spatial and temporal redundancy techniques are used to protect against faults. • Redundancy techniques assume that any fault will result in a visible program error (i.e., the Architectural Vulnerability Factor (AVF)) is 100 percent. • Over-design can hurt performance and drain power. AVF bit = Probability Bit Matters = # of Visible Errors # of Bit Flips from Particle Strikes As soft errors become more of a problem, protection will be needed even for every day PCs. Providing total redundancy is too expensive and assumes that AVF is 100%. Our work shows that AVF varies over time. n 0 Kristen Walcott, Greg Humphreys, Sudhanva Gurumurthi University of Virginia {walcott, humper, gurumurthi}@cs.virginia.edu Dynamic Prediction of Architectural Vulnerability What bits matter? Computer Science at the UNIVERSITY of VIRGINIA Rising Problem Dynamic AVF Prediction Calculating Vulnerability With an accurate predictor, redundancy may be turned on only when vulnerability is high. Preliminary results show that partial redundancy provides a significant performance boost over full redundancy. Next we will perform a more rigorous exploration of the design space of partial redundant multithreading implementations and investigate Future Work Prediction Results Challen ge
