Mark D. Hill Gene M. Amdahl & John P. Morgridge Professor Emeritus of Computer Sciences

Whatever may be the limitations which trammel inquiry elsewhere, we believe that the great state University of Wisconsin should ever encourage that continual and fearless sifting and winnowing by which alone the truth can be found.

--Report of the Board of Regents in 1849.

Research

See Wisconsin Multifacet Project as this sub-page is rarely updated.

My research targets parallel processing and the memory systems. Parallel work began decades before multicore chips. Memory system design is important because it largely determines a computer's sustained performance. My work emphasizes quantitative analysis (often requiring new evaluation techniques) of system-level (not just hardware) performance.

I co-lead the Wisconsin Multifacet Project with David Wood. Multifacet seeks to improve the servers that form the computational infrastructure for Internet web servers, databases, and other demanding applications. Work focuses on using the transistor bounty provided by Moore's Law to improve multiprocessor performance, cost, and fault tolerance, while also making these systems easier to design and program. Other recent results include:

• Arguing why cache coherence overheads are modest
• Obtaining the power saving of virtual caches without discarding compatibility
• Supporting die-stacked caches
• Distributing the gem5 simulator
• Explaining memory consistency and cache coherence
• Designing a deterministic multiprocessor

I also work on setting the direction for our community:

• Led CCC white paper
• Co-led ISAT workshop

Prior to Multifacet, I worked primarily on the Wisconsin Wind Tunnel Project, which focused on trade-offs for designing cost-effect parallel machines supporting shared memory.

Science is not a monument of received Truth but something that people do to look for truth. That endeavor, which has transformed the world in the last few centuries, does indeed teach values. Those values, among others, are honesty, doubt, respect for evidence, openness, accountability and tolerance and inview. These are unabashedly pragmatic working principles that guide the buzzing, testing, poking, probing, argumentative, gossiping, gadgety, joking, dreaming and tendentious cloud of activity--the writer and biologist Lewis Thomas once likened it to an anthill--that is slowly and thoroughly penetrating every nook and cranny of the world.

--Dennis Overbye, Elevating Science, Elevating Democracy Essay in New York Times, 01/27/2009, pp. D1 & D4.