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Proposal

Proposal. Sai – 9 th March’08. Motivation. NAND flash becoming more and more ubiquitous with promising features such as: very low power consumption compactness affordability, and so on

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Proposal

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  1. Proposal Sai – 9th March’08

  2. Motivation • NAND flash becoming more and more ubiquitous with promising features such as: • very low power consumption • compactness • affordability, and so on • Flash memory management is quite involved and decides the effective bandwidth available to an application • Garbage Collection is a very time consuming process • occurs only at a very less frequency, but determines worst-case performance • Evening out garbage collection over idle periods in flash access can be very lucrative

  3. Motivational Example  Mp3 player was run  Occasional writes were issued to the device in parallel Bottom line: if the prescribed performance 128 kbps is maintained

  4. Related Work • Greedy Approach: • Wu, M., Zwaenepoel, W., “eNVy: A Non-Volatile, Main Memory Storage System,” 1994. • Cost-benefit policy: • Kawaguchi, A., Nishioka, S., and Motoda, H., “A Flash-Memory Based File System,”, 1995. • Cost-Age-Time policy: • Mei-Ling Chiang, Paul C. H. Lee, Ruei-Chuan Chang, “Cleaning policies in mobile computers using flash, 1999. • Real-Time Garbage Collection: • Li-Pin Chang, Tei-Wei Kuo, Shi-Wu Lo, “Real-timegarbage collection for flash-memory storage systems of realtimeembedded systems,” ,2004. • The Challenge: • addressing orthogonal requirements of wear-leveling, garbage collection and utilization!!

  5. How/When Conventional Garbage Collection (CGC) works • The device is used up to the full extent , so, a new allocation will call for the “clean-up” operation • The PROBLEM: • Very time consuming • Need to merge a huge amount of data, copy and erase blocks for making space

  6. Sector Write Logic

  7. Problem Statements • Is there an efficient prediction algorithm that can work for a variety of workloads for application-adaptive management of flash memory? • How to dynamically optimize orthogonal metrics of power and bandwidth of NAND flash? • Implement the above two on a flash simulator and demonstrate gains

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