Measurements, Analysis and Modeling of RTOS System Calls Timing

Nowadays, the increasing system size, despite the need of achieving significant optimizations, requires a relevant presence of software because of its flexibility and easy manufacturability, with a level of complexity commonly requiring the management support of a Real-Time Operating System (RTOS). As far the software is concerned, recent literature reports many proposals focusing on application of software performance/power estimation and optimization techniques, but only relatively few include also the analysis of the operating system (OS) in a sufficiently systematic manner to be actually integrated in a tool-chain. Among the possible approaches to characterize the operating system, direct simulation of its code using available instruction-level simulators (ISS) can be considered in theory a correct solution but it is practically unfeasible. Large scale, fine grain simulation of operating system code, in fact, is affected by several problems: first of all, performance is crucial since even simple synchronization primitives require the execution of a huge amount of code; secondly, parametric estimators should be accurate enough to enable subsequent optimization; finally, most OS companies are hardly willing to disclose source code, which would be an important aid for operating system characterization.