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Mikinori Eto,Hidenori Umeno 제어로봇시스템학회 2008 제어로봇시스템학회 국제학술대회 논문집 Vol.2008 No.10
Modern computers are not only sufficiently powerful but also inexpensive. However there are few opportunities for application programs to use its capabilities. On the other hand, the number of computers has been increasing in the business sectors and other fields. Thus there are a lot of needless modern computer utilizations. As these solutions, researchers interested with the utilization of virtual machines (VMs) have been rising. The VM system enables consolidation of several real machines. As we consolidate real machine, another problem occurs. It may run several the same operating systems (OSs) which have identical application program, component and data on a machine. In this case, real machine’ memory has same contents. If many machines are consolidated by VM, it is verbose. We have been developing original VM system based on open source and high-quality VM system Xen. In this paper, we improved memory management system of Xen and consider the method for decreasing verbose memory on real machine. We propose the design and implementation method of content based page sharing method in Xen.
Yusuke Noguchi,Hidenori Umeno 제어로봇시스템학회 2008 제어로봇시스템학회 국제학술대회 논문집 Vol.2008 No.10
At present, the database management system occupies an important position in various application systems and in commercial systems. The study of database management system is attracting attention. We focus on open-source PostgreSQL comprising the function that it is not inferior to commercial database management system. But, there is the problem of the memory management in PostgreSQL. In a memory management method of PostgreSQL, the cache hit rate drops down under a specific condition. For example, when a transient large-scale search happens, most data including high frequency hit rate is flooded out of the buffer cache. And it causes the cache hit rate fall. It is thought that the buffer relocation method of current PostgreSQL is inefficient. To solve this problem, we suggest a multiple buffer cache method. The method is to divide the buffer cache into a plural number, and each buffer cache is managed individually according to the kind of data bound to each buffer cache. This can prevent the fall of the cache hit rate when a transient large-scale search happened.
Shenkun Liu,Hidenori Umeno 제어로봇시스템학회 2008 제어로봇시스템학회 국제학술대회 논문집 Vol.2008 No.10
In this paper we improve TPM (Transaction Processing Monitor) and aim at a further performance enhancement of PostgreSQL. Therefore we examined introduction of mechanism to change dynamically the number of the server connections to solve the problem in this study. We investigate the number of the most suitable connection by the load situation for this introduction, and we design TPM again in various points such as the design of the mechanism to analyze server state and the design of a mechanism to change the number of the connections. We report the result of the research, the contents of design, implementation and evaluation in this paper.