An Empirical Evaluation of OS Endsystem Support for Real-time CORBA Object Request Brokers

There is increasing demand to extend Object Request Broker (ORB) middleware to support distributed applications with stringent real-time requirements. However, lack of proper OS support can yield substantial inefficiency and unpredictability for ORB middleware. This paper provides two contributions to the study of OS support for real-time ORBs.

First, we empirically compare and evaluate the suitability of real-time operating systems, VxWorks and LynxOS, and general-purpose operating systems with real-time extensions, Windows NT, Solaris, and Linux, for real-time ORB middleware. While holding the hardware and ORB constant, we vary the operating system and measure platform-specific variations, such as latency, jitter, operation throughput, and CPU processing overhead. Second, we describe key areas where these operating systems must improve to support predictable, efficient, and scalable ORBs.

Our findings illustrate that general-purpose operating systems like Windows NT and Solaris are not yet suited to meet the demands of applications with stringent QoS requirements. However, LynxOS does enable predictable and efficient ORB performance, thereby making it a compelling OS platform for real-time CORBA applications. Linux provides good raw performance, though it is not a real-time operating system. Surprisingly, VxWorks does not scale robustly. In general, our results underscore the need for a measure-driven methodology to pinpoint sources of priority inversion and non-determinism in real-time ORB endsystems.

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