Tracing Hardware Monitors in the GR712RC Multicore Platform: Challenges and Lessons Learnt from a Space Case Study

Xavier Palomo, Mikel Fernandez, Sylvain Girbal, Enrico Mezzetti, Jaume Abella, Francisco J. Cazorla, Laurent Rioux

The demand for increased computing performance is driving industry in critical-embedded systems (CES) domains, e.g. space, towards the use of multicores processors. Multicores, however, pose several challenges that must be addressed before their safe adoption in critical embedded domains. One of the prominent challenges is software timing analysis, a fundamental step in the verification and validation process. Monitoring and profiling solutions, traditionally used for debugging and optimization, are increasingly exploited for software timing in multicores. In particular, hardware event monitors related to requests to shared hardware resources are building block to assess and restraining multicore interference. Modern timing analysis techniques build on event monitors to track and control the contention tasks can generate each other in a multicore platform. In this paper we look into the hardware profiling problem from an industrial perspective and address both methodological and practical problems when monitoring a multicore application. We assess pros and cons of several profiling and tracing solutions, showing that several aspects need to be taken into account while considering the appropriate mechanism to collect and extract the profiling information from a multicore COTS platform. We address the profiling problem on a representative COTS platform for the aerospace domain to find that the availability of directly-accessible hardware counters is not a given, and it may be necessary to the develop specific tools that capture the needs of both the user’s and the timing analysis technique requirements. We report challenges in developing an event monitor tracing tool that works for bare-metal and RTEMS configurations and show the accuracy of the developed tool-set in profiling a real aerospace application. We also show how the profiling tools can be exploited, together with handcrafted benchmarks, to characterize the application behavior in terms of multicore timing interference.

The paper will be presented in the session
Hardware II  SMT, tracing and more coherence – Thursday, July 9, 14:30 – 15:10 (CET) and 15:50 – 16:50 (CET)

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