Certification-cognizant scheduling of tasks with pessimistic frequency specification

Abstract

In modern embedded platforms, safety-critical functionalities that must be certified correct to very high levels of assurance may co-exist with less critical software that are not subject to certification requirements. Upon such platforms one seeks to satisfy two, sometimes contradictory, goals: (i) being able to certify the safety-critical functionalities under very conservative assumptions, and (ii) ensuring high utilization of platform resources even when actual run-time behavior does not live up to such pessimistic expectations. This paper describes efforts at designing scheduling algorithms that balance these two requirements, when scheduling recurrent tasks that are triggered by external events of unknown exact frequency.