1 Time/Utility Function Decomposition Techniques for Utility Accrual Scheduling Algorithms in Real-Time Distributed Systems Haisang Wu ⋆ , Binoy Ravindran ⋆ , E. Douglas Jensen † , and Peng Li ‡ ⋆ ECE Dept., Virginia Tech Blacksburg, VA 24061, USA {hswu02,binoy}@vt.edu † The MITRE Corporation Bedford, MA 01730, USA jensen@mitre.org ‡ Microsoft Corporation Redmond, WA 98052, USA pengli@microsoft.com Abstract We consider Real-Time CORBA 1.2’s d istributable t hreads (DTs), whose time constraints are specified using t ime/u tility f unctions (TUFs), operating in legacy environments. In legacy environments, system node resources—both physical and logical—are shared among time- critical DTs and local applications that may also be time-critical. Hence, DTs that are sched- uled using their propagated TUFs, as mandated by Real-Time CORBA 1.2’s Case 2 approach, may suffer performance degradation, if a node u tility a ccrual (UA) scheduler achieves higher locally accrued utility by giving higher eligibility to local threads than to DTs. To alleviate this, we consider decomposing TUFs of DTs into “sub-TUFs” for scheduling segments of DTs. We present decomposition techniques called UT , SCEQF , SCALL, OPTCON , and TUFS, which are specific to different classes of UA algorithms, such as those that use utility density, and those that use deadline as their key decision metric. Our experimental studies show that OPTCON and TUFS perform best for utility density-based UA algorithms, and SCEQF and SCALL perform best for deadline-based UA algorithms. Index Terms distributable thread, time/utility function, time constraint decomposition, Real-Time CORBA 1.2 I. Introduction The Object Management Group’s recent R eal-T ime C ORBA 1.2 standard [1] (abbre- viated here as RTC2) and Sun’s upcoming Distributed Real-Time Specification for Java IEEE Transactions on Computers, Accepted March 2005 1