title: Design and evaluation of an optimistic CPU: the warp engine

authors: Littin, Richard H.

abstract: Instruction pipelining, out-of-order execution, and branch prediction are techniques that improve performance in processors by manipulating the flow of instructions. These control flow manipulations alone are not adequate to allow large numbers of instructions to execute in parallel because performance is limited by accesses to the relatively slow memory system. Performance can be improved by speculating on the outcomes of control decisions, and the values of data in memory, returning results early. This thesis investigates the requirements of an architecture that speculates on control flow decisions and data values to improve performance through instruction level parallelism.

A new architecture, the WarpEngine, that speculates on control flow decisions and data values is presented. This architecture is shown to have the potential to extract performance through parallelism an order of magnitude larger than that obtained by contemporary microprocessors. Control speculation is achieved using a novel tree-based mechanism that produces multiple flows of control. This scalable mechanism is shown to generate a large group of instructions that can execute in parallel. Also, it is essential that memory accesses are allowed to occur out of programmed order. This form of data speculation is shown to break false data dependencies, improving performance. The use of state saving resources is examined and the limitations of in-order retirement schemes are shown. These results indicate that the management of these resources is critical to obtaining good performance.

Virtual ordered simulation is introduced as a new simulation methodology for modelling out-of-order and speculative architectures. This novel simulation technique is unique because each instruction is only inspected and processed once, and unlike other simulation methodologies unlimited resources can be modelled. Individual components can be constrained in isolation so that their effect on performance can be examined in detail. Investigations performed assuming unbounded resources provide new insight into the limits imposed by individual processor components.

The architecture presented shows potential for performance well beyond that of contemporary and research architectures. The insights into the limitations of processor components apply to many computer architectures.

text: Design and evaluation of an optimistic CPU: the warp engine Instruction pipelining, out-of-order execution, and branch prediction are techniques that improve performance in processors by manipulating the flow of instructions. These control flow manipulations alone are not adequate to allow large numbers of instructions to execute in parallel because performance is limited by accesses to the relatively slow memory system. Performance can be improved by speculating on the outcomes of control decisions, and the values of data in memory, returning results early. This thesis investigates the requirements of an architecture that speculates on control flow decisions and data values to improve performance through instruction level parallelism.

A new architecture, the WarpEngine, that speculates on control flow decisions and data values is presented. This architecture is shown to have the potential to extract performance through parallelism an order of magnitude larger than that obtained by contemporary microprocessors. Control speculation is achieved using a novel tree-based mechanism that produces multiple flows of control. This scalable mechanism is shown to generate a large group of instructions that can execute in parallel. Also, it is essential that memory accesses are allowed to occur out of programmed order. This form of data speculation is shown to break false data dependencies, improving performance. The use of state saving resources is examined and the limitations of in-order retirement schemes are shown. These results indicate that the management of these resources is critical to obtaining good performance.

Virtual ordered simulation is introduced as a new simulation methodology for modelling out-of-order and speculative architectures. This novel simulation technique is unique because each instruction is only inspected and processed once, and unlike other simulation methodologies unlimited resources can be modelled. Individual components can be constrained in isolation so that their effect on performance can be examined in detail. Investigations performed assuming unbounded resources provide new insight into the limits imposed by individual processor components.

The architecture presented shows potential for performance well beyond that of contemporary and research architectures. The insights into the limitations of processor components apply to many computer architectures.

year: 2000

title: On the chromatic index of Latin squares

authors: Cavenagh, Nicholas J.

abstract: A proper coloring of a Latin square of order n is an assignment of colors to its elements triples such that each row, column and symbol is assigned n distinct colors. Equivalently, a proper coloring of a Latin square is a partition into partial transversals. The chromatic index of a Latin square is the least number of colors needed for a proper coloring. We study the chromatic index of the cyclic Latin square which arises from the addition table for the integers modulo n. We obtain the best possible bounds except for the case when n=2 is odd and divisible by 3. We make some conjectures about the chromatic index, suggesting a generalization of Ryser's conjecture (that every Latin square of odd order contains a transversal).

text: On the chromatic index of Latin squares A proper coloring of a Latin square of order n is an assignment of colors to its elements triples such that each row, column and symbol is assigned n distinct colors. Equivalently, a proper coloring of a Latin square is a partition into partial transversals. The chromatic index of a Latin square is the least number of colors needed for a proper coloring. We study the chromatic index of the cyclic Latin square which arises from the addition table for the integers modulo n. We obtain the best possible bounds except for the case when n=2 is odd and divisible by 3. We make some conjectures about the chromatic index, suggesting a generalization of Ryser's conjecture (that every Latin square of odd order contains a transversal).

year: 2015

title: He Pikinga Waiora Implementation Framework: A tool for chronic disease intervention effectiveness in Maori and other indigenous communities

authors: Oetzel, John G.

subjects: Science & Technology

abstract: Introduction: Health outcomes for Māori are significantly worse than non-Maori in New Zealand; these inequities mirror those found in indigenous communities elsewhere. Evidence-based interventions with established efficacy may not be effective in indigenous communities without addressing specific implementation challenges. We present an implementation framework for chronic condition interventions for Māori.

Theory/Methods: The He Pikinga Waiora Implementation Framework has indigenous self-determination at its core and consists of four elements: cultural-centeredness, community engagement, systems thinking, and integrated knowledge translation.  All elements have demonstrated evidence of positive implementation outcomes.  A coding scheme derived from the Framework was applied to 13 studies of diabetes prevention in indigenous communities from a systematic review.

Results: Cross-tabulations demonstrated that culture-centeredness (p=.008) and community engagement (p=.009) explained differences in diabetes outcomes and community engagement (p=.098) explained difference in blood pressure outcomes.

Discussion and Conclusions: The He Pikinga Waiora Implementation Framework is well suited to advance implementation science for Māori and other indigenous communities. The framework has promise as a policy and planning tool to evaluate and design effective interventions for chronic disease prevention.

Lessons Learned: We needed to revise the coding framework in order to make the implication framework concrete.

Limitations: This study has a limitation in that we coded information about interventions from the published articles and not the interventions themselves. Additionally, the study only included 13 interventions.

Suggestions for Future Direction: Further research should provide stronger evidence of the usefulness of the framework particularly with Māori end-users. There will also be a need to understand the differential contribution of each of the four elements to health outcomes.

text: He Pikinga Waiora Implementation Framework: A tool for chronic disease intervention effectiveness in Maori and other indigenous communities Introduction: Health outcomes for Māori are significantly worse than non-Maori in New Zealand; these inequities mirror those found in indigenous communities elsewhere. Evidence-based interventions with established efficacy may not be effective in indigenous communities without addressing specific implementation challenges. We present an implementation framework for chronic condition interventions for Māori.

Theory/Methods: The He Pikinga Waiora Implementation Framework has indigenous self-determination at its core and consists of four elements: cultural-centeredness, community engagement, systems thinking, and integrated knowledge translation.  All elements have demonstrated evidence of positive implementation outcomes.  A coding scheme derived from the Framework was applied to 13 studies of diabetes prevention in indigenous communities from a systematic review.

Results: Cross-tabulations demonstrated that culture-centeredness (p=.008) and community engagement (p=.009) explained differences in diabetes outcomes and community engagement (p=.098) explained difference in blood pressure outcomes.

Discussion and Conclusions: The He Pikinga Waiora Implementation Framework is well suited to advance implementation science for Māori and other indigenous communities. The framework has promise as a policy and planning tool to evaluate and design effective interventions for chronic disease prevention.

Lessons Learned: We needed to revise the coding framework in order to make the implication framework concrete.

Limitations: This study has a limitation in that we coded information about interventions from the published articles and not the interventions themselves. Additionally, the study only included 13 interventions.

Suggestions for Future Direction: Further research should provide stronger evidence of the usefulness of the framework particularly with Māori end-users. There will also be a need to understand the differential contribution of each of the four elements to health outcomes.

year: 2018