Takashi Okumura

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Operating system extensions have been shown to be beneficial to implement custom kernel functionality. In most implementations, the extensions are made by an administrator with kernel loadable modules. An alternative approach is to provide a run-time system within the operating system itself that can execute user kernel extensions. In this paper, we(More)
We study a Rendezvous problem for 2 autonomous mobile robots in asynchronous settings with persistent memory called light. It is well known that Rendezvous is impossible when robots have no lights in basic common models, even if the system is semi-synchronous. On the other hand, Rendezvous is possible if robots have lights with a constant number of colors(More)
Because of user demands for better quality of service, network-aware applications have been of increasing necessity. To enable more control, the end-host operating system (OS) is the entity responsible for providing appropriate service level and API to user applications. However, most of the work in this area remains domain-specific and without a(More)
In this paper, we present “Netnice”, a mechanism that allows processes to throttle their own network bandwidth consumption. As the name suggests, it is inspired by the Unix nice command in that it allows users and administrators to limit the network resources used by individual processes in order to avoid impacting the performance of other processes. In the(More)
There have been increasing demands for proper monitoring and control in end-host systems, mainly for security and QoS purposes. Nevertheless, existing technologies are insufficient as primitives for end-host security. For example, Berkeley packet filter (BPF), the most popular monitoring infrastructure for many Unix systems, is intended for packet capturing(More)
Medical information systems carry sensitive data, which necessitates security and privacy. However, there is well-known trade-off between usability and security, and security can harm care providers and patients. This paper addresses the trade-off between security and usability in medical systems, and presents a case where higher security with better(More)