The StarBase Project Overview

StarBase Overview

• built on top of the RT-Mach operating system
• supports real-time transactions with firm deadlines
• seeks to minimize the number of high-priority transactions which miss their deadlines
• uses no a priori information about the transaction workload

Problems Faced by Real-Time Databases

• resource contention
• data contention
• specifying/enforcing timing constraints

Dealing with Resource Contention

• RT-Mach provides:
  • priority-cognizant thread scheduling and a real-time thread model
  • Basic Priority Inheritance synchronization for non-preemptible resources
• StarBase employs these features to:
  • service transactions in priority order
  • ensure transactions progress according to priority
  • ensure transactions access resource managers in priority order

Dealing with Data Contention

• WAIT-X(S) optimistic concurrency control
• priority-based commit test
• Precise Serialization to reduce unnecessary aborts

Enforcing Deadlines

• RT-Mach provides:
  • real-time thread model
  • real-time clocks and timers
• StarBase uses these features to abort transactions and reply at or before deadline
• StarBase:
  • avoids race conditions between deadline handler and transaction
  • avoids interference by low-priority transactions

Future Work

• incorporate a priori information/offline analysis for predictability
• port to other real-time OS kernels that support POSIX .4 extension

[Starbase] [Security] [Predict] [Schedule] [Multimedia] [Dependability]