| Title | Multi-version Checkpointing for Flash File Systems |
| Author | *Shih-Chun Chou (Department of Computer Science and Information Engineering, National Taiwan University, Taiwan), Yuan-Hao Chang, Yuan-Hung Kuan (Institute of Information Science, Academia Sinica, Taiwan), Po-Chun Huang (Department of Computer Science and Engineering, Yuan Ze University, Taiwan), Che-Wei Tsao (Department of Computer Science and Information Engineering, National Taiwan University, Taiwan) |
| Page | pp. 436 - 443 |
| Keyword | file system, multi-version checkpointing, reliability |
| Abstract | Reliability has become a critical design issue in flash storage systems, because of the adoption of the low-cost, high-error-rate flash chips to fulfill the needs of the fast-growing storage capacity. In this paper, a multi-version checkpointing strategy is proposed to resolve the reliability issue of flash storage systems from the perspective of flash file systems. The proposed strategy can efficiently and effectively utilize checkpoints of file systems to guarantee the integrity and consistency of flash file systems after files or flash pages are corrupted. By utilizing the coexistence fact of multiple versions of the same data in flash memory, a control/recovery mechanism is presented to maintain checkpoints and to recover file systems with minimized management and recovery time overheads. A series of experiments was conducted based on realistic traces that were collected from benchmarks running over flash file systems in Linux operating systems. The results illustrate that the proposed strategy can significantly improve the reliability of flash file systems, as compared with other existing designs. |
| Title | Relay-based Key Management to Support Secure Deletion for Resource-Constrained Flash-Memory Storage Devices |
| Author | Wei-Lin Wang (Department of Computer Science, National Tsing Hua University, Taiwan), Yuan-Hao Chang (Institute of Information Science, Academia Sinica, Taiwan), *Po-Chun Huang (Department of Computer Science and Engineering, Yuan Ze University, Taiwan), Chia-Heng Tu (Smart Network System Institute, Institute for Information Industry, Taiwan), Hsin-Wen Wei (Department of Electrical Engineering, Tamkang University, Taiwan), Wei-Kuan Shih (Department of Computer Science, National Tsing Hua University, Taiwan) |
| Page | pp. 444 - 449 |
| Keyword | reliability, flash memory, key management, secure deletion |
| Abstract | The support of secure deletion on formatting a file system is to make sure that when a file system is formatted, there is no way to get any file content back again. Due to the fast-growing storage capacity, the performance of secure deletion to file systems on resource-constrained flash storage devices has become a critical issue. In contrast to the existing works that take a long time on overwriting/resetting all the file contents of a file system, we propose an efficient secure deletion scheme to securely delete all the contents of a file system without rewriting file contents. Thus, secure deletion to file systems can be efficiently achieved and can be independent of the device capacity and file systems. A series of experiments was conducted with realistic workloads to evaluate the capability of the proposed scheme. The results show that the proposed scheme achieves secure deletion with limited performance overheads in most cases. |
| Title | Peak-to-average Pumping Efficiency Improvement for Charge Pump in Phase Change Memories |
| Author | Huizhang Luo (Chongqing University, China), Jingtong Hu (Oklahoma State University, U.S.A.), *Liang Shi (Chongqing University, China), Chun Jason Xue (City University of Hong Kong, Hong Kong), Qingfeng Zhuge (Chongqing University, China) |
| Page | pp. 450 - 455 |
| Keyword | PCM, Charge Pump |
| Abstract | The pumping efficiency of a PCM chip is a concave function of the write current. Based on the characteristics of the concave function, the overall pumping efficiency can be improved if the write current is uniform. In this paper, we propose the peak-to-average (PTA) write scheme, which smooths the write current fluctuation by regrouping write units. An off-line optimal Integer Programming (IP) formulation and an efficient online algorithm are proposed to achieve this goal. Experimental results show that PTA can improve the charge pump efficiency greatly with little overhead. |
| Title | Exploiting Parallelism of Imperfect Nested Loops with Sibling Inner Loops on Coarse-Grained Reconfigurable Architectures |
| Author | *Xinhan Lin, Shouyi Yin, Leibo Liu, Shaojun Wei (Tsinghua University, China) |
| Page | pp. 456 - 461 |
| Keyword | CGRA, software pipelining, imperfect nested loop, outer-level pipelining, kernel compression |
| Abstract | Coarse-grained reconfigurable architecture (CGRA) is a promising platform for loop acceleration, but existing software pipelining methods cannot achieve satisfactory performance on a fair number of imperfect nested loops, especially those with sibling inner loops. To tackle this problem, this paper makes 2 contributions: 1) a 2-level pipelining method with an effective II optimization strategy for the imperfect loops with sibling inner loops; 2) a novel kernel compression method to reduce oversize kernel. Experiment results show that our approach can achieve much higher performance than the state-of-the-art approaches at acceptable costs. |
| Title | SlowMo – Enhancing Mobile Gesture-Based Authentication Schemes via Sampling Rate Optimization |
| Author | *Kent W. Nixon, Xiang Chen, Zhi-Hong Mao, Yiran Chen (University of Pittsburgh, U.S.A.) |
| Page | pp. 462 - 467 |
| Keyword | gesture, security, sample, rate |
| Abstract | In the era of network service, the user authentication become more indispensable but also vulnerable. Traditional user verification approaches such as PIN or pattern lock suffer from easy hacking and replica. A promising approach to continuous user verification on mobile is gesture-based security, Compare to the traditional authentications, the gesture-based security utilize the user interacts with the device as a dynamic authentication pattern in real-time. It has high complexity and better reliability. But it still lack sufficient research on data sampling and preprocessing techniques on classification accuracy. In this work, we develop SlowMo, a novel gesture security technique, and utilize it for user classification in low sampling-rate environments. The proposed algorithm provides maximum classification accuracy at a sampling rate of 4Hz with extreme low power consumption suggesting a more capable adaptation to the security environment. |