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Galileo/SCI Home Page;The Galileo and SCI Projects at Wisconsin;Table of contents;Galileo;Project description;Publications;Related projects;SCI at Wisconsin;Project description;Publications;Project Members;Galileo at Wisconsin;Galileo is a project being conducted in the;computer architecture group;at the University of Wisconsin-Madison. Our project focuses on the medium-;to long-term evolution of processor and system architectures, with an emphasis;on the memory system. Specifically, we are studying what the;relationship between the processor and main memory will be in future;systems: completely separate, as today, or integrated (and if so, to what extent).;Processing capability and bit storage may merge in at least two ways.;Because of increasing off-chip penalties (in issuable instructions) and/or;limited off-chip bandwidth, designers may place more and more capacity;on the processor chip and module, until eventually a sizable fraction;of main memory resides on-chip (represented by the arrow labeled MOP;in the above diagram). A different possibility is the migration of;processor capability onto the DRAM chips themselves, eventually;obviating the central processor (see the IRAM arrow above).;Our specific research currently focuses on the following areas:;Examining the performance impact of large memory latencies and;limited memory bandwidth in current and future microprocessor-based systems;Performance modeling of the various design points along the;processor/memory (P/M) integration spectrum;Cache hierarchy design for P/M integrated systems;Design of main memory banks in a P/M integrated system;Program execution in systems with multiple integrated chips;(DataScalar architectures);Galileo-specific publications:;Exploiting Optical Interconnects to Eliminate Serial Bottlenecks;Doug Burger and James R. Goodman.;Appears in the 3rd International Conference on Massively Parallel Processing Using Optical Interconnects, October, 1996.;DataScalar Architectures and the SPSD Execution Model;Doug Burger, Stefanos Kaxiras, and James R. Goodman.;University of Wisconsin-Madison Computer Sciences Department Technical Report 1317, July, 1996.;Quantifying Memory Bandwidth Limitations of Current and Future Microprocessors;Doug Burger, James R. Goodman, and Alain Kägi.;Appears in the 23rd International Symposium on Computer Architecture, May, 1996.;The Declining Effectiveness of Dynamic Caching for General-Purpose Microprocessors;Douglas C. Burger, James R. Goodman, and Alain Kägi.;University of Wisconsin-Madison Computer Sciences Department Technical Report 1261, January, 1995.;Related projects:;IRAM - UC-Berkeley;PPRAM - Kyushu Univeristy, Japan;SCI at Wisconsin;Our group is also closely involved with research relating to cache-coherent;shared-memory multiprocessor design, specifically studying the Scalable Coherent;Interface coherence and transport layers.;We are using SCI, which is an IEEE standard (1596-1992), as a base platform for;the exploration of our ideas.;The SCI standard specifies a linked-list based hardware coherence protocol,;which includes support for efficient synchronization primitives;(Queue On Lock Bit, or QOLB), as;well as optimizations for different sharing patterns, such as;pairwise-sharing and fresh read-sharing. The standard also includes a definition;for an extremely high-bandwidth (1 GB/s), low latency transport layer in between;processing elements or individual clusters.;We are currently performing SCI-related research on the following topics:;Extending SCI with logarithmically-growing sharing structures;Efficient hardware synchronization for shared-memory multiprocessors;A scalability study of the base SCI protocol, including its standard extensions;Aggressive consistency models for shared-memory multiprocessors;Wisconsin SCI Publications:;The GLOW Cache Coherence Protocol Extensions for Widely Shared Data;Stefanos Kaxiras and James R. Goodman.;To appear in the proceedings of the 10th ACM International Conference on Supercomputing, May, 1996.;Kiloprocessor Extensions to SCI;Stefanos Kaxiras.;To appear in the proceedings of the 10th International Parallel Processing Symposium, April, 1996.;Techniques for Reducing Overheads of Shared-Memory Multiprocessing;Alain Kägi, Nagi Aboulenein, Douglas C. Burger, and James R. Goodman.;Appears as "Best Architecture Paper" in the proceedings of the 9th ACM;International Conference on Supercomputing, July, 1995.;Also University of Wisconsin-Madison Computer Sciences Department TR #1266, May, 1995.;Simulation of the SCI Transport Layer on the Wisconsin Wind Tunnel;Douglas C. Burger and James R. Goodman.;In the proceedings of the Second International Workshop on SCI-based High-Performance Low-Cost Computing, March, 1995.;Also University of Wisconsin-Madison Computer Sciences Department Technical Report 1265, March, 1995.;Hierarchical Extensions to SCI;James R. Goodman and Stefanos Kaxiras.;University of Wisconsin-Madison Computer Sciences Department Technical Report 1235, July 1994.;Extending the Scalable Coherent Interface for Large-Scale Shared-Memory;Ross Evan Johnson.;University of Wisconsin-Madison Computer Sciences Department Technical Report 1136, February 1993.;Hardware Support for Synchronization in the Scalable Coherent Interface (SCI);Nagi M. Aboulenein, Stein Gjessing, James R. Goodman, and Philip J. Woest.;University of Wisconsin-Madison Computer Sciences Department Technical Report 1117, November 1992.;Interconnect Topologies with Point-to-Point Rings;Ross E. Johnson and James R. Goodman.;University of Wisconsin-Madison Computer Sciences Department Technical Report 1058, December 1991.; Analysis of the SCI Ring;Steven L. Scott, James A. Goodman, and Mary K. Vernon.;University of Wisconsin-Madison Computer Sciences Department Technical Report 1055, November 1991.;Lower Bounds on Latency for Scalable Linked-List Cache Coherence;Ross Johnson.;University of Wisconsin-Madison Computer Sciences Department Technical Report 1029, June 1991.;An Analysis of Synchronization Mechanisms in Shared-Memory Multiprocessors;Philip J. Woest and James R. Goodman.;University of Wisconsin-Madison Computer Sciences Department Technical Report 1005, February 1991.;A Set of Efficient Synchronization Primitives for a Large-Scale Shared-Memory Multiprocessor;James. R. Goodman, Mary. K. Vernon, Philip. J. Woest.;In the proceedings of the Third International Conference on Architectural Support for Programming Languages and Operating Systems, April, 1989.;Also University of Wisconsin-Madison Computer Sciences Department Technical Report 814.;Project participants:; Faculty; Jim Goodman; Graduate students; Doug Burger; Alain Kägi; Stefanos Kaxiras; Project alumni;Nagi Aboulenein;Ross Johnson;Steve Scott;Last modified: Fri Aug 2 09:12:00 1996 by Doug Burger;(dburger@cs.wisc.edu);