Studying Several Proposals for the Adaptation of the DTable Scheduler to Advanced Switching

Advanced Switching (AS) is a new fabric-interconnect technology that further enhances the capabilities of PCI Express. On the other hand, the provision of Quality of Service (QoS) in computing and communication environments is currently the focus of much discussion and research in industry and academia. A key component for networks with QoS support is the egress link scheduling algorithm. AS defines two egress link schedulers: The virtual channel arbitration table scheduler and the minimum bandwidth egress link scheduler. The table-based scheduler is simple to implement and can offer good latency bounds with a fixed packet size. However, it does not work properly with variable packet sizes and faces the problem of bounding the bandwidth and latency assignments. We have proposed a new table-based scheduler, which we have called Deficit Table (DTable) scheduler, that works properly with variable packet sizes. Moreover, we have proposed a methodology to configure this table-based scheduler that partially decouples the bandwidth and latency assignments. In this paper we propose several possible modifications to the original AS table scheduler in order to implement the DTable scheduler. Moreover, we review our proposals to provide bandwidth and latency requirements over AS using the DTable scheduler. Finally, we evaluate our proposals in a multimedia scenario and compare the performance of the DTable scheduler with the performance of the minimum bandwidth scheduler.