TAP: Task-Aware Profiling on Integrated Systems

Jeremy Giesen, Enrico Mezzetti, Jaume Abella, Francisco J. Cazorla

Abstract: Hardware Performance Monitors (HPM) are increasingly exploited for timing verification and validation of time-critical embedded systems (TECS). HPMs are typically collected at the lowest software level, which makes it difficult to unequivocally account events to specific run-time entities, a prerequisite for any form of analysis, without relying on ad-hoc support from the run-time or operating system layer. The latter, however, is either unavailable or not fully adequate for verification requirements. Moreover, timing-related concerns in the analysis of embedded systems are typically addressed in the final stages of the software development process where multiple tasks are fully or partially integrated on the platform and it is therefore hard, if not impossible, to enforce controlled testing scenarios where contributions to event counts can be dissected. In this work, we present TAP a generic concept for allowing Task-Aware Profiling of individual tasks in an already integrated system on MPSoCs with on-core and off-core HPM support. The proposed approach combines a lightweight user-level configurable API and minimally intrusive extensions to the operating system layer to enforce separation of contexts when collecting HPM. We implement and assess TAP on top of an Infineon AURIX MPSoC and the OSEK-compliant ERIKA Enterpise RTOS, offering a consistent and intuitive interface for governing and filtering the different sources of events. Our results on synthetic and automotive benchmarks show that TAP can transparently gather and filter the events of interest while incurring negligible overheads.