Incorporating the deadline floor protocol in ada

Abstract

The Ada 2005 standard introduced "Earliest Deadline First" (EDF) as one of the supported dispatching policies. The standard specifies the "Stack Resource Protocol" (SRP) as the protocol for resource sharing among EDF tasks. During the time the SRP has been in the standard it has shown to be a relatively complex protocol. Recently, a new protocol has been proposed for resource sharing in EDF. This new protocol, called "Deadline Floor inheritance Protocol" (DFP), is simpler and more efficient than SRP while keeping all its good properties. In this paper we briefly describe both protocols and compare them from the complexity point of view. In light of its simplicity, we propose to change the language standard to include DFP instead of SRP. Some alternative modifications of the Ada Reference Manual are pointed out in order to include DFP in the most straightforward way.

The Deadline Floor Protocol and Ada

“…And to accommodate hierarchical dispatching (see Section 4) we define the new policy as EDF Within Priorities. We will not attempt to give a full definition appropriate for the ARM 1 .…”