Application systems in real-time processing fields, in addition to those systems whose most important requirement is to complete processing within a given response time, also include systems whose aims are to raise throughput within the response time restrictions, in which a high degree of multi-tasking is of primary importance. The paper makes proposals on task scheduling and OS functions in highly multi-tasking real-time processing domains, and outlines a research project presently being undertaken in NTT to study real-time OS performance evaluation methods geared to these domains.>