An autonomous I/O module for low-cost media on-demand servers

This paper focuses on the design of low cost media-on-demand servers. Limitations of single-processor architectures and their input/output subsystems are shown. An original device called autonomous media I/O module (AMIOM) is proposed. The device consists of a local CPU, a local buffer memory, and an interconnection unit that allows the communication with two subordinate buses. The objective is to migrate the stream and its control from the host and to make the I/O subsystem scalable. Features of the proposed AMIOM are presented in detail. The interconnection and operation of multiple modules are discussed. Performance of the improved design is evaluated with taking into consideration communication overheads. The effect of attaching multiple I/O devices to each of the module´s subordinate buses is also analyzed. Comparison of the classical design and the improved one shows significant performance gain.