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Thesis Defense - Steinke

Consistency Model Transitions in Shared Memory
Robert Steinke
Computer Science PhD Candidate

The traditional assumption about memory is that a read returns the value written by the most recent write. However in multiprocessing environments, the processes independently and simultaneously submit reads and writes resulting in a partial order of memory operations. In this partial order, the definition of most recent may be ambiguous. Memory consistency models were developed to formally specify the values that may be returned by read operations given that memory operations may be only partially ordered. The concept of varying the consistency model of memory has primarily been used for scientific computing. For this class of applications, different programs may require different consistency, but any particular program always requires a single consistency model. The hypothesis of this work is that the abstraction of a shared memory interface with variable consistency is useful for other types of applications. In addition, these applications may want to change consistency at run time. The class of collaboration application will be used as an example of programs that may want to operate under different consistency at different points in their execution. A lattice based framework of consistency models will be presented so that transitions between any two consistency models can be described by a path in the lattice. In addition, a transition theory will be presented specifying the allowable behavior of memory when a single program submits operations under more than one consistency model.

Committee: Gary Nutt, Professor
Clarence (Skip) Ellis, Professor
Alexander Wolf, Associate Professor
Harry Jordan, Professor
Amer Diwan, Assistant Professor
Department of Computer Science
University of Colorado Boulder
Boulder, CO 80309-0430 USA
May 5, 2012 (14:20)