Time Petri Nets在实时系统的建模和性能分析中得到广泛应用,而冲突是Petri网及其扩展模型的重要行为,解决冲突是正确分析模型动态行为的关键.目前随机Petri网、混合Petri网和区间速率连续Petri网的冲突检测方法由于没有考虑到时间约束...Time Petri Nets在实时系统的建模和性能分析中得到广泛应用,而冲突是Petri网及其扩展模型的重要行为,解决冲突是正确分析模型动态行为的关键.目前随机Petri网、混合Petri网和区间速率连续Petri网的冲突检测方法由于没有考虑到时间约束因此无法在TPN网中使用.时间约束的引入使得Time Petri Nets模型的使能和触发语义比Petri网模型的语义复杂,冲突检测变得更加困难.为了计算冲突发生的时间和概率,首先根据时间约束,给出了变迁持续使能时延迟区间的计算方法,并证明了该方法的合理性和完备性;然后在此基础上定义并证明了Time Petri Nets模型中不冲突的检测方法;并提出了Time Petri Nets模型的冲突检测方法,给出了冲突时间区间和变迁实施概率的计算方法;最后通过实例验证说明了该方法的正确性和有效性.展开更多
GPU (Graphics Processing Unit) is used in various areas. Therefore, the demand for the verification of GPU programs is increasing. In this paper, we suggest the method to detect bank conflict by using symbolic executi...GPU (Graphics Processing Unit) is used in various areas. Therefore, the demand for the verification of GPU programs is increasing. In this paper, we suggest the method to detect bank conflict by using symbolic execution. Bank conflict is one of the bugs happening in GPU and it leads the performance of programs lower. Bank conflict happens when some processing units in GPU access the same shared memory. Symbolic execution is the method to analysis programs with symbolic values. By using it, we can detect bank conflict on GPU programs which use many threads. We implement a prototype of the detector for bank conflict and evaluate it with some GPU programs. The result states that we can detect bank conflict on the programs with no loop regardless of the number of threads.展开更多
In this paper, we propose a Multi-granularity Spatial Access Control （MSAC） model, in which multi- granularity spatial objects introduce more types of policy rule conflicts than single-granularity objects do. To ana...In this paper, we propose a Multi-granularity Spatial Access Control （MSAC） model, in which multi- granularity spatial objects introduce more types of policy rule conflicts than single-granularity objects do. To analyze and detect these conflicts, we first analyze the conflict types with respect to the relationship among the policy rules, and then formalize the conflicts by template matrices. We designed a model-checking algorithm to detect potential conflicts by establishing formalized matrices of the policy set. Lastly, we conducted experiments to verify the performance of the algorithm using various spatial data sets and rule sets. The results show that the algorithm can detect all the formalized conflicts. Moreover, the algorithm＇s efficiency is more influenced by the spatial object granularity than the size of the rule set.展开更多
无冲突复制数据类型(conflict-free replicated data types,简称CRDT)是一种封装了冲突消解策略的分布式复制数据类型,它能够保证分布式系统中副本节点间的强最终一致性,即执行了相同更新操作的副本节点具有相同的状态.CRDT协议设计精巧...无冲突复制数据类型(conflict-free replicated data types,简称CRDT)是一种封装了冲突消解策略的分布式复制数据类型,它能够保证分布式系统中副本节点间的强最终一致性,即执行了相同更新操作的副本节点具有相同的状态.CRDT协议设计精巧,不易保证其正确性.旨在采用模型检验技术验证一系列CRDT协议的正确性.具体而言,构建了一个可复用的CRDT协议描述与验证框架,包括网络通信层、协议接口层、具体协议层与规约层.网络通信层描述副本节点之间的通信模型,实现了多种类型的通信网络.协议接口层为已知的CRDT协议(分为基于操作的协议与基于状态的协议)提供了统一的接口.在具体协议层,用户可以根据协议的需求选用合适的底层通信网络.规约层则描述了所有CRDT协议都需要满足的强最终一致性与最终可见性(所有的更新操作最终都会被所有的副本节点接收并处理).使用TLA+形式化规约语言实现了该框架,然后以Add-Wins Set复制数据类型为例,展示了如何使用框架描述具体协议,并使用TLC模型检验工具来验证协议的正确性.展开更多
文摘Time Petri Nets在实时系统的建模和性能分析中得到广泛应用,而冲突是Petri网及其扩展模型的重要行为,解决冲突是正确分析模型动态行为的关键.目前随机Petri网、混合Petri网和区间速率连续Petri网的冲突检测方法由于没有考虑到时间约束因此无法在TPN网中使用.时间约束的引入使得Time Petri Nets模型的使能和触发语义比Petri网模型的语义复杂,冲突检测变得更加困难.为了计算冲突发生的时间和概率,首先根据时间约束,给出了变迁持续使能时延迟区间的计算方法,并证明了该方法的合理性和完备性;然后在此基础上定义并证明了Time Petri Nets模型中不冲突的检测方法;并提出了Time Petri Nets模型的冲突检测方法,给出了冲突时间区间和变迁实施概率的计算方法;最后通过实例验证说明了该方法的正确性和有效性.
文摘GPU (Graphics Processing Unit) is used in various areas. Therefore, the demand for the verification of GPU programs is increasing. In this paper, we suggest the method to detect bank conflict by using symbolic execution. Bank conflict is one of the bugs happening in GPU and it leads the performance of programs lower. Bank conflict happens when some processing units in GPU access the same shared memory. Symbolic execution is the method to analysis programs with symbolic values. By using it, we can detect bank conflict on GPU programs which use many threads. We implement a prototype of the detector for bank conflict and evaluate it with some GPU programs. The result states that we can detect bank conflict on the programs with no loop regardless of the number of threads.
基金supported by the National Natural Science Foundation of China(Nos.51204185 and 41674030)Natural Youth Science Foundation of Jiangsu Province,China(No.BK20140185)+1 种基金China Postdoctoral Science Foundation(No.2016M601909)the Fundamental Research Funds for the Central Universities(No.2014QNA44)
文摘In this paper, we propose a Multi-granularity Spatial Access Control （MSAC） model, in which multi- granularity spatial objects introduce more types of policy rule conflicts than single-granularity objects do. To analyze and detect these conflicts, we first analyze the conflict types with respect to the relationship among the policy rules, and then formalize the conflicts by template matrices. We designed a model-checking algorithm to detect potential conflicts by establishing formalized matrices of the policy set. Lastly, we conducted experiments to verify the performance of the algorithm using various spatial data sets and rule sets. The results show that the algorithm can detect all the formalized conflicts. Moreover, the algorithm＇s efficiency is more influenced by the spatial object granularity than the size of the rule set.
文摘无冲突复制数据类型(conflict-free replicated data types,简称CRDT)是一种封装了冲突消解策略的分布式复制数据类型,它能够保证分布式系统中副本节点间的强最终一致性,即执行了相同更新操作的副本节点具有相同的状态.CRDT协议设计精巧,不易保证其正确性.旨在采用模型检验技术验证一系列CRDT协议的正确性.具体而言,构建了一个可复用的CRDT协议描述与验证框架,包括网络通信层、协议接口层、具体协议层与规约层.网络通信层描述副本节点之间的通信模型,实现了多种类型的通信网络.协议接口层为已知的CRDT协议(分为基于操作的协议与基于状态的协议)提供了统一的接口.在具体协议层,用户可以根据协议的需求选用合适的底层通信网络.规约层则描述了所有CRDT协议都需要满足的强最终一致性与最终可见性(所有的更新操作最终都会被所有的副本节点接收并处理).使用TLA+形式化规约语言实现了该框架,然后以Add-Wins Set复制数据类型为例,展示了如何使用框架描述具体协议,并使用TLC模型检验工具来验证协议的正确性.
