Computer Science, The College of William & Mary

Sun Formally Acknowledges the Research Contribution of Z. Zhang, Z. Zhu, and X. Zhang to the Memory System Design in UltraSPARC IIIi Processor

A permutation-based memory interleaving technique, called "XOR interleaving" or "permutation interleaving" proposed by Zhao Zhang (Ph.D.'02), Zhichun Zhu (Ph.D.'03), and Xiaodong Zhang has been adopted in the Sun MicroSystems' UltraSPARC IIIi processor. A paper about this technique entitled "A permutation-based page interleaving scheme to reduce row-buffer conflicts and exploit data locality" was presented and published in the 33rd Annual IEEE/ACM International Symposium on Microarchitecture (Micro-33, pp. 32-41, Monterey, California, December 10-13, 2000). Having conducted intensive experiments and thorough analyses, the three W&M researchers showed that address mapping conflicts at the cache level, including address conflicts and write-back conflicts, will inevitably propagate to the memory address space under a standard memory interleaving method, causing a significant memory access delay. This important finding was first published in this Micro-33 paper, and their proposed permutation interleaving technique effectively solves the conflict problem with a trivial hardware cost. In addition to supporting the XOR interleaving technique in UltraSPARC IIIi processors, the finding of memory address conflict propagations in the Micro-33 paper has also been quoted in Technical Manuals of UltraSPARC IIIi processor related systems by the Sun MicroSystems.

In July 2005, the Sun MicroSystems Inc. sent a formal acknowledgement letter to the College of William and Mary to recognize the research contribution of Z. Zhang, Z. Zhu, and X. Zhang. The UltraSPARC IIIi processors are used in in both entry level servers, such as Sun Fire V210, V240, V250, and V440 servers, and in workstation and desktop products, such as Sun Blade 1500 workstations.

Xiaodong Zhang, Lettie Pate Evans Professor of Computer Science and the Department Chair, says, "I and my former students Zhao Zhang (an assistant professor of electrical and computer engineering at the Iowa State University) and Zhichun Zhu (an assistant professor of electrical and computer engineering at the University of Illinois at Chicago) feel very rewarding to see the strong impact of our research work to the computer industry and to our daily computing operations".

The Department of Computer Science
The College of William & Mary
McGlothlin-Street Hall, Room 126