DATE: Thursday, Julty 22, 2010
TIME: 12:00 pm - 1:00 pm

Sangyeun Cho, University of Pittsburgh

TITLE: Reducing Energy Consumption of PRAM Storage with Bit-Level Update Skipping

The phase-change RAM (PRAM) technology is maturing to production levels. PRAM has a RAM-like interface and offers higher performance than NAND flash memory for certain operations. Its manufacturability and scalability have been demonstrated by multiple vendors. In this talk, I will describe our recent work on reducing energy consumption of a PRAM storage. The first technique is "Flip-N-Write," which reduces bit-level updates in PRAM devices by performing efficient read-modify-write operations on writes. By opportunistically re-encoding the data to write, Flip-N-Write guarantees that the maximum number of bit updates is halved. Next, we will describe a content-aware block placement strategy. By identifying a similar free block for each block to write, we reduce the average number of bit updates. Finally, I will describe our on-going effort to build research infrastructures for studying various design trade-offs of a PRAM storage system.

Sangyeun Cho received the BS degree in computer engineering from Seoul National University in 1994 and the PhD degree in computer science from the University of Minnesota in 2002. In 1999, he joined the System LSI Division of Samsung Electronics Co., Giheung, Korea, and contributed to the development of Samsung's flagship embedded processor core family CalmRISC(TM). He was a lead architect of CalmRISC-32, a 32-bit microprocessor core, and designed its memory hierarchy including caches, DMA, and stream buffers. Since 2004, he has been with the Computer Science Department at the University of Pittsburgh, where he is currently an assistant professor. His research interests are in the area of computer architecture and embedded systems with particular focus on performance, power and reliability aspects of memory hierarchy design for next-generation multicore systems. Sangyeun is the happy father of Seyun (b. December 2009).

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