强实时条件下光纤通道仲裁环带宽分配方法

光纤通道是一个为适应高性能信息传输要求而提出的计算机通讯协议,仲裁环是光纤通道的基本拓扑结构之一.为解决网络消息集实时发送的问题,研究了光纤通道仲裁环拓扑在强实时条件下的通信性能.依据实时系统中的周期任务模型和光纤通道仲裁环协议规定的访问公平机制,采用负载匹配算法提出了一种适用于仲裁环网络的带宽分配方法.推导并证明了采用该方法时在最坏情况下消息集强实时的网络可达负载率不低于50％.

Bandwidth allocation for FC-AL under hard real time condition

Fibre channel is a computer communication protocol designed to meet many requir ements related to the ever increasing demand for high performance information tr ansfer. Arbitrated loop is one of basic fibre channel topology. To guarantee mes sage deadlines for the whole message set, the real-time characteristics of fibre channel arbitrated loop was studied. A real-time system is required to complete its work and deliver its services on a timely basis. The periodic ta sk model is a well-known deterministic workload. With its various extensions, the model characterizes accurately many traditional hard real-time applications. A simple operational definition was adopted. The job is a hard real-time job. The user requires the validation that the system always meet the timing constraints. Under the access fairness algorithm of arbitrated loop,a bandwidth allocation sc heme based on the traffic load balance of each node was proposed. The bound of the worst case achievable utilization for the scheme was derived and formally pr oved.