A unified approach called partition-and-recur for developing efficient and correct algorithmic programs is presented. An algorithm (represented by recurrence and initiation) is separated from program, and special att...A unified approach called partition-and-recur for developing efficient and correct algorithmic programs is presented. An algorithm (represented by recurrence and initiation) is separated from program, and special attention is paid to algorithm manipulation rather than program calculus. An algorithm is exactly a set of mathematical formulae. It is easier for formal derivation and proof. After getting efficient and correct algorithm, a trivial transformation is used to get a final program. The approach covers several known algorithm design techniques, e.g. dynamic programming, greedy, divide-and-conquer and enumeration, etc. The techniques of partition and recurrence are not new. Partition is a general approach for dealing with complicated objects and is typically used in divide-and-conquer approach. Recurrence is used in algorithm analysis, in developing loop invariants and dynamic programming approach. The main contribution is combining two techniques used in typical algorithm development into a unified and systematic approach to develop general efficient algorithmic programs and presenting a new representation of algorithm that is easier for understanding and demonstrating the correctness and ingenuity of algorithmic programs.展开更多
Previous descriptions of memory consistency models in shared-memory multiprocessor systems are mainly expressed as constraints on the memory access event ordering and hence are hardwae-centric. This paper presents a ...Previous descriptions of memory consistency models in shared-memory multiprocessor systems are mainly expressed as constraints on the memory access event ordering and hence are hardwae-centric. This paper presents a framework of memory consistency models which describes the memory consistency model on the behavior level.Based on the understanding that the behavior of an execution is determined by the execution order of confiicting accesses, a memory consistency model is defined as an interprocessor synchronization mechanism which orders the execution of operations from different processors. Synchronization order of an execution under certain consistency model is also defined. The synchronization order, together with the program order,determines the behavior of an execution.This paper also presents criteria for correct program and correct implementation of consistency models. Regarding an implementation of a consistency model as certain memory event ordering constraints, this paper provides a method to prove the correctness of consistency model implementations, and the correctness of the lock-based cache coherence protocol is proved with this method.展开更多
基金the 863 Hi-Tech Programmethe National Natural ScienceFoundation of China
文摘A unified approach called partition-and-recur for developing efficient and correct algorithmic programs is presented. An algorithm (represented by recurrence and initiation) is separated from program, and special attention is paid to algorithm manipulation rather than program calculus. An algorithm is exactly a set of mathematical formulae. It is easier for formal derivation and proof. After getting efficient and correct algorithm, a trivial transformation is used to get a final program. The approach covers several known algorithm design techniques, e.g. dynamic programming, greedy, divide-and-conquer and enumeration, etc. The techniques of partition and recurrence are not new. Partition is a general approach for dealing with complicated objects and is typically used in divide-and-conquer approach. Recurrence is used in algorithm analysis, in developing loop invariants and dynamic programming approach. The main contribution is combining two techniques used in typical algorithm development into a unified and systematic approach to develop general efficient algorithmic programs and presenting a new representation of algorithm that is easier for understanding and demonstrating the correctness and ingenuity of algorithmic programs.
文摘Previous descriptions of memory consistency models in shared-memory multiprocessor systems are mainly expressed as constraints on the memory access event ordering and hence are hardwae-centric. This paper presents a framework of memory consistency models which describes the memory consistency model on the behavior level.Based on the understanding that the behavior of an execution is determined by the execution order of confiicting accesses, a memory consistency model is defined as an interprocessor synchronization mechanism which orders the execution of operations from different processors. Synchronization order of an execution under certain consistency model is also defined. The synchronization order, together with the program order,determines the behavior of an execution.This paper also presents criteria for correct program and correct implementation of consistency models. Regarding an implementation of a consistency model as certain memory event ordering constraints, this paper provides a method to prove the correctness of consistency model implementations, and the correctness of the lock-based cache coherence protocol is proved with this method.
