Dependable Resource Sharing for Compositional Real-Time Systems

Hierarchical scheduling frameworks (HSFs) have been extensively investigated as a paradigm for facilitating temporal isolation between components that need to be integrated on a single shared processor. In the presence of shared resources, however, temporal isolation may break when one of the accessing components executes longer than specified during global resource access. The ability to confine such temporal faults makes the HSF more dependable. As a solution we propose a stack-resource-policy (SRP)-based synchronization protocol for HSFs, named Hierarchical Synchronization protocol with Temporal Protection (HSTP). When a component exceeds its specified critical-section length, HSTP enforces a component to self-donate its own budget to accelerate the resource release. In addition, a component that blocks on a locked resource may donate budget. The schedulability of those components that are independent of the locked resource is unaffected. HSTP efficiently limits the propagation of temporal faults to resource-sharing components by disabling local preemptions in a component during resource access. We finally show that HSTP is SRP-compliant and applies to existing synchronization protocols for HSFs.