A study of the relationship between the performance and dependability of a fault-tolerant computer

This thesis studies the relationship by creating a tool (FTAPE) that integrates a high stress workload generator with fault injection and by using the tool to evaluate system performance under error conditions. The workloads are comprised of processes which are formed from atomic components that represent CPU, memory, and I/O activity. The fault injector is software-implemented and is capable of injecting any memory addressable location, including special registers and caches. This tool has been used to study a Tandem Integrity S2 Computer. Workloads with varying numbers of processes and varying compositions of CPU, memory, and I/O activity are first characterized in terms of performance. Then faults are injected into these workloads. The results show that as the number of concurrent processes increases, the mean fault latency initially increases due to increased contention for the CPU. However, for even higher numbers of processes (less than 3 processes), the mean latency decreases because long latency faults are paged out before they can be activated

Techniques for Aging, Soft Errors and Temperature to Increase the Reliability of Embedded On-Chip Systems

This thesis investigates the challenge of providing an abstracted, yet sufficiently accurate reliability estimation for embedded on-chip systems. In addition, it also proposes new techniques to increase the reliability of register files within processors against aging effects and soft errors. It also introduces a novel thermal measurement setup that perspicuously captures the infrared images of modern multi-core processors

RAID Organizations for Improved Reliability and Performance: A Not Entirely Unbiased Tutorial (1st revision)

RAID proposal advocated replacing large disks with arrays of PC disks, but as the capacity of small disks increased 100-fold in 1990s the production of large disks was discontinued. Storage dependability is increased via replication or erasure coding. Cloud storage providers store multiple copies of data obviating for need for further redundancy. Varitaions of RAID based on local recovery codes, partial MDS reduce recovery cost. NAND flash Solid State Disks - SSDs have low latency and high bandwidth, are more reliable, consume less power and have a lower TCO than Hard Disk Drives, which are more viable for hyperscalers.Comment: Submitted to ACM Computing Surveys. arXiv admin note: substantial text overlap with arXiv:2306.0876

Cross-layer Soft Error Analysis and Mitigation at Nanoscale Technologies

This thesis addresses the challenge of soft error modeling and mitigation in nansoscale technology nodes and pushes the state-of-the-art forward by proposing novel modeling, analyze and mitigation techniques. The proposed soft error sensitivity analysis platform accurately models both error generation and propagation starting from a technology dependent device level simulations all the way to workload dependent application level analysis

Proposal of an Adaptive Fault Tolerance Mechanism to Tolerate Intermittent Faults in RAM

[EN] Due to transistor shrinking, intermittent faults are a major concern in current digital systems. This work presents an adaptive fault tolerance mechanism based on error correction codes (ECC), able to modify its behavior when the error conditions change without increasing the redundancy. As a case example, we have designed a mechanism that can detect intermittent faults and swap from an initial generic ECC to a specific ECC capable of tolerating one intermittent fault. We have inserted the mechanism in the memory system of a 32-bit RISC processor and validated it by using VHDL simulation-based fault injection. We have used two (39, 32) codes: a single error correction-double error detection (SEC-DED) and a code developed by our research group, called EPB3932, capable of correcting single errors and double and triple adjacent errors that include a bit previously tagged as error-prone. The results of injecting transient, intermittent, and combinations of intermittent and transient faults show that the proposed mechanism works properly. As an example, the percentage of failures and latent errors is 0% when injecting a triple adjacent fault after an intermittent stuck-at fault. We have synthesized the adaptive fault tolerance mechanism proposed in two types of FPGAs: non-reconfigurable and partially reconfigurable. In both cases, the overhead introduced is affordable in terms of hardware, time and power consumption.This research was supported in part by the Spanish Government, project TIN2016-81,075-R, and by Primeros Proyectos de Investigacion (PAID-06-18), Vicerrectorado de Investigacion, Innovacion y Transferencia de la Universitat Politecnica de Valencia (UPV), project 20190032.Baraza Calvo, JC.; Gracia-Morán, J.; Saiz-Adalid, L.; Gil Tomás, DA.; Gil, P. (2020). Proposal of an Adaptive Fault Tolerance Mechanism to Tolerate Intermittent Faults in RAM. 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Characterization of multi-bit soft error events in advanced SRAMs. IEEE International Electron Devices Meeting 2003. doi:10.1109/iedm.2003.1269335Schroeder, B., Pinheiro, E., & Weber, W.-D. (2011). DRAM errors in the wild. Communications of the ACM, 54(2), 100-107. doi:10.1145/1897816.1897844BanaiyanMofrad, A., Ebrahimi, M., Oboril, F., Tahoori, M. B., & Dutt, N. (2015). Protecting caches against multi-bit errors using embedded erasure coding. 2015 20th IEEE European Test Symposium (ETS). doi:10.1109/ets.2015.7138735Kim, J., Sullivan, M., Lym, S., & Erez, M. (2016). All-Inclusive ECC: Thorough End-to-End Protection for Reliable Computer Memory. 2016 ACM/IEEE 43rd Annual International Symposium on Computer Architecture (ISCA). doi:10.1109/isca.2016.60Hwang, A. A., Stefanovici, I. A., & Schroeder, B. (2012). Cosmic rays don’t strike twice. ACM SIGPLAN Notices, 47(4), 111-122. doi:10.1145/2248487.2150989Gil-Tomás, D., Gracia-Morán, J., Baraza-Calvo, J.-C., Saiz-Adalid, L.-J., & Gil-Vicente, P.-J. (2012). Studying the effects of intermittent faults on a microcontroller. Microelectronics Reliability, 52(11), 2837-2846. doi:10.1016/j.microrel.2012.06.004Plasma CPU Modelhttps://opencores.org/projects/plasmaArlat, J., Aguera, M., Amat, L., Crouzet, Y., Fabre, J.-C., Laprie, J.-C., … Powell, D. (1990). Fault injection for dependability validation: a methodology and some applications. IEEE Transactions on Software Engineering, 16(2), 166-182. doi:10.1109/32.44380Gil-Tomas, D., Gracia-Moran, J., Baraza-Calvo, J.-C., Saiz-Adalid, L.-J., & Gil-Vicente, P.-J. (2012). Analyzing the Impact of Intermittent Faults on Microprocessors Applying Fault Injection. IEEE Design & Test of Computers, 29(6), 66-73. doi:10.1109/mdt.2011.2179514Rashid, L., Pattabiraman, K., & Gopalakrishnan, S. (2010). Modeling the Propagation of Intermittent Hardware Faults in Programs. 2010 IEEE 16th Pacific Rim International Symposium on Dependable Computing. doi:10.1109/prdc.2010.52Amiri, M., Siddiqui, F. M., Kelly, C., Woods, R., Rafferty, K., & Bardak, B. (2016). FPGA-Based Soft-Core Processors for Image Processing Applications. Journal of Signal Processing Systems, 87(1), 139-156. doi:10.1007/s11265-016-1185-7Hailesellasie, M., Hasan, S. R., & Mohamed, O. A. (2019). MulMapper: Towards an Automated FPGA-Based CNN Processor Generator Based on a Dynamic Design Space Exploration. 2019 IEEE International Symposium on Circuits and Systems (ISCAS). doi:10.1109/iscas.2019.8702589Mittal, S. (2018). A survey of FPGA-based accelerators for convolutional neural networks. Neural Computing and Applications, 32(4), 1109-1139. doi:10.1007/s00521-018-3761-1Intel Completes Acquisition of Alterahttps://newsroom.intel.com/news-releases/intel-completes-acquisition-of-altera/#gs.mi6ujuAMD to Acquire Xilinx, Creating the Industry’s High Performance Computing Leaderhttps://www.amd.com/en/press-releases/2020-10-27-amd-to-acquire-xilinx-creating-the-industry-s-high-performance-computingKim, K. H., & Lawrence, T. F. (s. f.). Adaptive fault tolerance: issues and approaches. [1990] Proceedings. Second IEEE Workshop on Future Trends of Distributed Computing Systems. doi:10.1109/ftdcs.1990.138292Gonzalez, O., Shrikumar, H., Stankovic, J. A., & Ramamritham, K. (s. f.). Adaptive fault tolerance and graceful degradation under dynamic hard real-time scheduling. Proceedings Real-Time Systems Symposium. doi:10.1109/real.1997.641271Jacobs, A., George, A. D., & Cieslewski, G. (2009). Reconfigurable fault tolerance: A framework for environmentally adaptive fault mitigation in space. 2009 International Conference on Field Programmable Logic and Applications. doi:10.1109/fpl.2009.5272313Shin, D., Park, J., Park, J., Paul, S., & Bhunia, S. (2017). Adaptive ECC for Tailored Protection of Nanoscale Memory. IEEE Design & Test, 34(6), 84-93. doi:10.1109/mdat.2016.2615844Silva, F., Muniz, A., Silveira, J., & Marcon, C. (2020). CLC-A: An Adaptive Implementation of the Column Line Code (CLC) ECC. 2020 33rd Symposium on Integrated Circuits and Systems Design (SBCCI). doi:10.1109/sbcci50935.2020.9189901Mukherjee, S. S., Emer, J., Fossum, T., & Reinhardt, S. K. (s. f.). Cache scrubbing in microprocessors: myth or necessity? 10th IEEE Pacific Rim International Symposium on Dependable Computing, 2004. Proceedings. doi:10.1109/prdc.2004.1276550Saleh, A. M., Serrano, J. J., & Patel, J. H. (1990). Reliability of scrubbing recovery-techniques for memory systems. IEEE Transactions on Reliability, 39(1), 114-122. doi:10.1109/24.52622X9SRA User’s Manual (Rev. 1.1)https://www.manualshelf.com/manual/supermicro/x9sra/user-s-manual-1-1.htmlChishti, Z., Alameldeen, A. R., Wilkerson, C., Wu, W., & Lu, S.-L. (2009). Improving cache lifetime reliability at ultra-low voltages. Proceedings of the 42nd Annual IEEE/ACM International Symposium on Microarchitecture - Micro-42. doi:10.1145/1669112.1669126Datta, R., & Touba, N. A. (2011). Designing a fast and adaptive error correction scheme for increasing the lifetime of phase change memories. 29th VLSI Test Symposium. doi:10.1109/vts.2011.5783773Kim, J., Lim, J., Cho, W., Shin, K.-S., Kim, H., & Lee, H.-J. (2016). Adaptive Memory Controller for High-performance Multi-channel Memory. JSTS:Journal of Semiconductor Technology and Science, 16(6), 808-816. doi:10.5573/jsts.2016.16.6.808Yuan, L., Liu, H., Jia, P., & Yang, Y. (2015). Reliability-Based ECC System for Adaptive Protection of NAND Flash Memories. 2015 Fifth International Conference on Communication Systems and Network Technologies. doi:10.1109/csnt.2015.23Zhou, Y., Wu, F., Lu, Z., He, X., Huang, P., & Xie, C. (2019). SCORE. ACM Transactions on Architecture and Code Optimization, 15(4), 1-25. doi:10.1145/3291052Lu, S.-K., Li, H.-P., & Miyase, K. (2018). Adaptive ECC Techniques for Reliability and Yield Enhancement of Phase Change Memory. 2018 IEEE 24th International Symposium on On-Line Testing And Robust System Design (IOLTS). doi:10.1109/iolts.2018.8474118Chen, J., Andjelkovic, M., Simevski, A., Li, Y., Skoncej, P., & Krstic, M. (2019). Design of SRAM-Based Low-Cost SEU Monitor for Self-Adaptive Multiprocessing Systems. 2019 22nd Euromicro Conference on Digital System Design (DSD). doi:10.1109/dsd.2019.00080Wang, X., Jiang, L., & Chakrabarty, K. (2020). LSTM-based Analysis of Temporally- and Spatially-Correlated Signatures for Intermittent Fault Detection. 2020 IEEE 38th VLSI Test Symposium (VTS). doi:10.1109/vts48691.2020.9107600Ebrahimi, H., & G. Kerkhoff, H. (2018). Intermittent Resistance Fault Detection at Board Level. 2018 IEEE 21st International Symposium on Design and Diagnostics of Electronic Circuits & Systems (DDECS). doi:10.1109/ddecs.2018.00031Ebrahimi, H., & Kerkhoff, H. G. (2020). A New Monitor Insertion Algorithm for Intermittent Fault Detection. 2020 IEEE European Test Symposium (ETS). doi:10.1109/ets48528.2020.9131563Hsiao, M. Y. (1970). A Class of Optimal Minimum Odd-weight-column SEC-DED Codes. IBM Journal of Research and Development, 14(4), 395-401. doi:10.1147/rd.144.0395Benso, A., & Prinetto, P. (Eds.). (2004). Fault Injection Techniques and Tools for Embedded Systems Reliability Evaluation. Frontiers in Electronic Testing. doi:10.1007/b105828Gracia, J., Saiz, L. J., Baraza, J. C., Gil, D., & Gil, P. J. (2008). Analysis of the influence of intermittent faults in a microcontroller. 2008 11th IEEE Workshop on Design and Diagnostics of Electronic Circuits and Systems. doi:10.1109/ddecs.2008.4538761ZC702 Evaluation Board for the Zynq-7000 XC7Z020 SoChttps://www.xilinx.com/support/documentation/boards_and_kits/zc702_zvik/ug850-zc702-eval-bd.pd

Fault- and Yield-Aware On-Chip Memory Design and Management

Ever decreasing device size causes more frequent hard faults, which becomes a serious burden to processor design and yield management. This problem is particularly pronounced in the on-chip memory which consumes up to 70% of a processor' s total chip area. Traditional circuit-level techniques, such as redundancy and error correction code, become less effective in error-prevalent environments because of their large area overhead. In this work, we suggest an architectural solution to building reliable on-chip memory in the future processor environment. Our approaches have two parts, a design framework and architectural techniques for on-chip memory structures. Our design framework provides important architectural evaluation metrics such as yield, area, and performance based on low level defects and process variations parameters. Processor architects can quickly evaluate their designs' characteristics in terms of yield, area, and performance. With the framework, we develop architectural yield enhancement solutions for on-chip memory structures including L1 cache, L2 cache and directory memory. Our proposed solutions greatly improve yield with negligible area and performance overhead. Furthermore, we develop a decoupled yield model of compute cores and L2 caches in CMPs, which show that there will be many more L2 caches than compute cores in a chip. We propose efficient utilization techniques for excess caches. Evaluation results show that excess caches significantly improve overall performance of CMPs

Memory region: a system abstraction for managing the complex memory structures of multicore platforms

The performance of modern many-core systems depends on the effective use of their complex cache and memory structures, and this will likely become more pronounced with the impending arrival of on-chip 3D stacked and non-volatile off-chip byte-addressable memory. Yet to date, operating systems have not treated memory as a first class schedulable resource, embracing memory heterogeneity. This dissertation presents a new software abstraction, called ‘memory region’, which denotes the current set of physical memory pages actively used by workloads. Using this abstraction, memory resources can be scheduled for applications to fully exploit a platform's underlying cache and memory system, thereby gaining improved performance and predictability in execution, particularly for the consolidated workloads seen in virtualized and cloud computing infrastructures. The abstraction's implementation in the Xen hypervisor involves the run-time detection of memory regions, the scheduled mapping of these regions to caches to match performance goals, and maintaining region-to-cache mappings using per-cache page tables. This dissertation makes the following specific contributions. First, its region scheduling method proposes that the location of memory blocks rather than CPU utilization is the principal determinant where workloads are run. It proposes a new scheduling method, the region scheduling that the location of memory blocks determines where the workloads are run. Second, treating memory blocks as first-class resources, new methods for efficient cache management are shown to improve application performance as well as the performance of certain operating system functions. Third, explicit memory scheduling makes it possible to disaggregate operating systems, without the need to change OS sources and with only small markups of target guest OS functionality. With this method, OS functions can be mapped to specific desired platform components, such as file system confined to running on specific cores and using only certain memory resources designated for its use. This can improve performance for applications heavily dependent on certain OS functions, by dynamically providing those functions with the resources needed for their current use, and it can prevent performance-critical application functionality from being needlessly perturbed by OS functions used for other purposes or by other jobs. Fourth, extensions of region scheduling can also help applications deal with the heterogeneous memory resources present in future systems, including on-chip stacked DRAM and NUMA or even NVRAM memory modules. More generally, regions scheduling is shown to apply to memory structures with well-defined differences in memory access latencies.Ph.D

Architectural Techniques for Disturbance Mitigation in Future Memory Systems

With the recent advancements of CMOS technology, scaling down the feature size has improved memory capacity, power, performance and cost. However, such dramatic progress in memory technology has increasingly made the precise control of the manufacturing process below 22nm more difficult. In spite of all these virtues, the technology scaling road map predicts significant process variation from cell-to-cell. It also predicts electromagnetic disturbances among memory cells that easily deviate their circuit characterizations from design goals and pose threats to the reliability, energy efficiency and security. This dissertation proposes simple, energy-efficient and low-overhead techniques that combat the challenges resulting from technology scaling in future memory systems. Specifically, this dissertation investigates solutions tuned to particular types of disturbance challenges, such as inter-cell or intra-cell disturbance, that are energy efficient while guaranteeing memory reliability. The contribution of this dissertation will be threefold. First, it uses a deterministic counter-based approach to target the root of inter-cell disturbances in Dynamic random access memory (DRAM) and provide further benefits to overall energy consumption while deterministically mitigating inter-cell disturbances. Second, it uses Markov chains to reason about the reliability of Spin-Transfer Torque Magnetic Random-Access Memory (STT-RAM) that suffers from intra-cell disturbances and then investigates on-demand refresh policies to recover from the persistent effect of such disturbances. Third, It leverages an encoding technique integrated with a novel word level compression scheme to reduce the vulnerability of cells to inter-cell write disturbances in Phase Change Memory (PCM). However, mitigating inter-cell write disturbances and also minimizing the write energy may increase the number of updated PCM cells and result in degraded endurance. Hence, It uses multi-objective optimization to balance the write energy and endurance in PCM cells while mitigating intercell disturbances. The work in this dissertation provides important insights into how to tackle the critical reliability challenges that high-density memory systems confront in deep scaled technology nodes. It advocates for various memory technologies to guarantee reliability of future memory systems while incurring nominal costs in terms of energy, area and performance

Efficient Learning Machines

Computer scienc

Improved LEACH Protocol based on Moth Flame Optimization Algorithm for Wireless Sensor Networks

Wireless sensor nodes are made up of small electronic devices designed for detecting, determining, and sending data under severe physical conditions. These sensor nodes rely heavily on batteries for energy, which drain at a quicker pace due to the extensive communication and processing tasks they must carry out. Managing this battery resource is the major challenge in wireless sensor networks (WSNs). This work aims at developing an improved performance and energy-efficient low-energy adaptive clustering hierarchy (IPE-LEACH) that can extend the lifespan of networks. This paper proposes a novel LEACH protocol that uses the moth flame optimization (MFO) algorithm for clustering and routing to increase the longevity of the sensor network. IPE-LEACH proved to have a better cluster-head (CH) selection technique by eliminating redundant data, thereby extending the network lifetime. IPE-LEACH was compared with four other existing algorithms, and it performed better than: original LEACH by 60%, EiP-LEACH by 45%, LEACH-GA by 58%, and LEACH-PSO by 13.8%. It can therefore be concluded that IPE-LEACH is a promising clustering algorithm that has the potential to realize high flexibility in WSNs in case the CH fails.