Memory Architecture for RealTime

1
Memory Architecture for Real-Time

• David Bacon
• IBM Research

2
The Problem

• Real-time gt need to predict execution time
• Determinism Good
• Turn off cache
• Model cache in excruciating detail (e.g., Wilhelm
  et al.)
• But
• For complex systems WCET (worst-case execution
  time) is fiction

3
Proposed Solution

• So
• Its a non-deterministic world live with it
• In fact, embrace it randomize and decorrelate
• Over long time scale, non-determinism is okay
• Overprovision enough to make failure extremely
  low probability

4
General Rules

• All levels (HW, OS, JVM, Application)
• Randomize
• Decorrelate
• Bound
• Its worth paying for
• Robust real-time
• Eliminate performance cliffs