Faculty Advisor
Dr. Douglas C. Schmidt

Grant
$18,000 on 7/1/98

Funding
Purchase of a Pentium PC, and graduate student stipend, for developing and evaluating a flexible framework for dynamicd istributed real-time scheduling.

Developing and Evaluating a Flexible Framework for Dynamic Distributed Real-Time Scheduling Abstract
In theory, dynamic scheduling can alleviate many of the limitations of static scheduling. In practice, however, implementations of conventional dynamic scheduling techniques, such as earliest deadline first (EDF) and minimum laxity first (MLF), do not preserve the schedulability guarantees offered by static techniques. To address the limitations of existing dynamic scheduling techniques, we propose to enhance the existing static scheduling framework found in The ACE ORB (TAO) to support dynamic and hybrid static/dynamic scheduling of operations for ORB middleware and real-time applications. The scope of this project consists of two main objectives. First, we propose to complete current work on dynamic scheduling features in TAO's existing event service and scheduling service, and to add features for distributed dynamic scheduling to these services using a flexible strategized scheduling framework. Second, we propose to conduct a set of experiments to examine the effects of varying platform, application, and middleware factors on scheduling behavior.

Current Status as of 7/25/98
Dynamically prioritized message queue classes have been coded and added to the Adaptive Communication Environment ACE framework upon which TAO is built. These classes extend the existing ACE_Message_Queue class, which implements an abstraction based on the UNIX System V STREAMS message queueing model. The new classes provide dynamic message prioritization capabilities, including distinct prioritization strategies based on either message laxity or time to deadline.

Coding of a test to verify correct operation of these classes is in progress, and when complete will be added to the "one-button" test suite in ACE. Following this, the dynamic message queues will be integrated with the TAO event service to provide dynamically scheduled message dispatching.

Web Site
https://www.cs.wustl.edu/~cdgill/research/scheduling/USENIX/project.html