The growing trend of network virtualization results in a widespread adoption of virtual switches in virtualized environments. However, virtual switching is confronted with great performance challenges regarding packet...The growing trend of network virtualization results in a widespread adoption of virtual switches in virtualized environments. However, virtual switching is confronted with great performance challenges regarding packet classification especially in Open Flow-based software defined networks. This paper first takes an insight into packet classification in virtual Open Flow switching, and points out that its performance bottleneck is dominated by flow table traversals of multiple failed mask probing for each arrived packet. Then we are motivated to propose an efficient packet classification algorithm based on counting bloom filters. In particular, counting bloom filters are applied to predict the failures of flow table lookups with great possibilities, and bypass flow table traversals for failed mask probing. Finally, our proposed packet classification algorithm is evaluated with real network traffic traces by experiments. The experimental results indicate that our proposed algorithm outperforms the classical one in Open v Switch in terms of average search length, and contributes to promote virtual Open Flow switching performance.展开更多
Traditional HPC （High Performance Computing） cluster is built on top of physical machines. It is usually not practical to reassign these machines to other tasks due to the fact that software installation is time con...Traditional HPC （High Performance Computing） cluster is built on top of physical machines. It is usually not practical to reassign these machines to other tasks due to the fact that software installation is time consuming. As a result, these machines are usually dedicated for the cluster usage. Virtualization technology provides an abstract layer which allows several different operating systems （with different software packages） running on top of one physical machine. Cloud computing provides an easy way for the user to manage and interact with the computing resources （the virtual machines in this case）. In this work, we demonstrate the feasibility of building a cloud-based cluster for HPC on top of a set of desktop computers that are interconnected by means of Fast Ethernet. Our cluster has several advantages. For instance, the deployment time of the cluster is quite fast： We need only 5 min to deploy a cluster of 30 machines, Besides, several performance benchmarks have been carried out. As expected, the embarrassingly parallel problem has the linear relationship between the performance and the cluster size.展开更多
With the full implementation of the Code of Criminal Procedure, the application of the rules of the exclusion of the illegal evidences is more inclined to the protection of the human rights. However, in the process of...With the full implementation of the Code of Criminal Procedure, the application of the rules of the exclusion of the illegal evidences is more inclined to the protection of the human rights. However, in the process of the implementation of the new laws, the problems in view of the rules of the exclusion of the illegal evidences are also prominent, which are mainly reflected in the ambiguity of the scope of the application, the start of the program of the exclusion, and the formalization the trial certificates and other aspects. Therefore, in this article, the author starts from the concept of the illegal evidences, and expounds the principles of the exclusion and the abilities of the evidences, and especially explores the abilities of the evidences and the probative forces. From the differences between the two, the author strictly proves the virtualization of the standards, in order to provide the positive solutions for strengthening the exclusionary procedure of the illegal evidences.展开更多
基金supported in part by National Natural Science Foundation of China(61272148,61572525,61502056,and 61602525)Hunan Provincial Natural Science Foundation of China(2015JJ3010)Scientific Research Fund of Hunan Provincial Education Department(15B009,14C0285)
文摘The growing trend of network virtualization results in a widespread adoption of virtual switches in virtualized environments. However, virtual switching is confronted with great performance challenges regarding packet classification especially in Open Flow-based software defined networks. This paper first takes an insight into packet classification in virtual Open Flow switching, and points out that its performance bottleneck is dominated by flow table traversals of multiple failed mask probing for each arrived packet. Then we are motivated to propose an efficient packet classification algorithm based on counting bloom filters. In particular, counting bloom filters are applied to predict the failures of flow table lookups with great possibilities, and bypass flow table traversals for failed mask probing. Finally, our proposed packet classification algorithm is evaluated with real network traffic traces by experiments. The experimental results indicate that our proposed algorithm outperforms the classical one in Open v Switch in terms of average search length, and contributes to promote virtual Open Flow switching performance.
文摘Traditional HPC （High Performance Computing） cluster is built on top of physical machines. It is usually not practical to reassign these machines to other tasks due to the fact that software installation is time consuming. As a result, these machines are usually dedicated for the cluster usage. Virtualization technology provides an abstract layer which allows several different operating systems （with different software packages） running on top of one physical machine. Cloud computing provides an easy way for the user to manage and interact with the computing resources （the virtual machines in this case）. In this work, we demonstrate the feasibility of building a cloud-based cluster for HPC on top of a set of desktop computers that are interconnected by means of Fast Ethernet. Our cluster has several advantages. For instance, the deployment time of the cluster is quite fast： We need only 5 min to deploy a cluster of 30 machines, Besides, several performance benchmarks have been carried out. As expected, the embarrassingly parallel problem has the linear relationship between the performance and the cluster size.
文摘With the full implementation of the Code of Criminal Procedure, the application of the rules of the exclusion of the illegal evidences is more inclined to the protection of the human rights. However, in the process of the implementation of the new laws, the problems in view of the rules of the exclusion of the illegal evidences are also prominent, which are mainly reflected in the ambiguity of the scope of the application, the start of the program of the exclusion, and the formalization the trial certificates and other aspects. Therefore, in this article, the author starts from the concept of the illegal evidences, and expounds the principles of the exclusion and the abilities of the evidences, and especially explores the abilities of the evidences and the probative forces. From the differences between the two, the author strictly proves the virtualization of the standards, in order to provide the positive solutions for strengthening the exclusionary procedure of the illegal evidences.
