Abstract PRET Machines

Prior work has shown that it is possible to design microarchitectures called PRET machines that deliver precise and repeatable timing of software execution without sacrificing performance. That prior work provides specific designs for PRET microarchitectures and compares them against conventional designs. This paper defines a class of microarchitectures called abstract PRET machines (APMs) that capture the essential temporal properties of PRET machines. We show that APMs deliver deterministic timing with no loss of performance for a family of real-time problems consisting of sporadic event streams with deadlines equal to periods. On the other hand, we observe a tradeoff between deterministic timing and the ability to meet deadlines for sporadic event streams with constrained deadlines.