Abstract

Compared with rapid technology advancements in multicore processors and rapid changes from computing-intensive to highly data-intensive applications, operating systems have been evolved very slowly for several decades. Application users are facing to two major challenges in today's computing environment.On the top level of the system hierarchy, private and shared caches are equipped for many cores to access concurrently, inevitably causing access conflicts to degrade execution performance.On the bottom level, the performance bottleneck of "memory wall" has been shifted to "disk wall" that is a serious bottleneck for many data-intensive applications. Since processor caches and disk storage are not in the major scope of operating system management, and their increasingly complex operations are not transparent to application users, the above mentioned performance issues have not been effectively addressed at any level of computer systems.

We have made a continuous effort to enhance operating systems with two objectives: (1) to well utilize rich but complex resources of multicore processors and (2) to access disk data as fast as possible. At the multicore processor level, we are developing new resource allocation management to improve the effective caching capacity per core and/or per thread, and to minimize congestion in off-chip memory accesses by coordinating memory bandwidth sharing. At the storage level, we enable operating systems to effectively exploit "sequential locality" and let random accesses to stay in buffer cache or/and in SSD (flash memory storage). We will mainly discuss the research issues and challenges in multicore processors in this talk.

Bio of the Speaker

Xiaodong Zhang is the Robert M. Critchfield Professor in Engineering,and Chairman of the Department of Computer Science and Engineering at the Ohio State University.

His research interests cover a wide spectrum in the areas of high performance and distributed systems. Several technical innovations and research results from his team have been adopted or being developed in commercial products and open source systems with direct impact to some key computing operations, including the permutation memory interleaving technique first in the Sun MicroSystems' UltraSPARC IIIi processor and then in the Sun's dual-core Gemini Processor, the token thrashing protection mechanism and the Clock-Pro page replacement algorithm for memory management in the Linux Kernel and NetBSD. He has been elected as an IEEE Fellow for his "contributions to computer memory systems".

Xiaodong Zhang was the Director of Advanced Computational Research Program at the National Science Foundation, 2001-2004. He is the associate Editor-in-Chief of IEEE Transactions on Parallel and Distributed Systems, and is also serving on the Editorial Boards of IEEE Transactions on Computers, IEEE Micro, and Journal of Parallel and Distributed Computing. He is the program chair or co-chair in ICPP'07, WWW'08, and ICDCS'09. 

He received his Ph.D. in Computer Science from University of Colorado at Boulder, and his B.S. in Electrical Engineering from Beijing University of Technology.