Multicore AUTOSAR operating system
Multicore systems are one of the hot topics in ECU development. AUTOSAR recognized this trend some years ago and recently released version 4.0 of the specifications. Version 4.0 supports multicore MCUs. The basic mechanisms are built into the AUTOSAR operating system (OS) and consist of the following features:
- OS applications are the basis for the mapping of application code to cores. In the past they have been used to define the scope of memory protection. In AUTOSAR release 4.0 this was extended to support the distribution of applications. In practice this means that all objects that pertain to the same OS application (tasks, ISRs, alarms and the like) are placed on the same core.
- The scheduling policy has not changed, but each core has its “own” (local) scheduler which selects the tasks to be run from the OS-applications bound to the core.
- Communication between cores is implemented with an IOC (Inter OS-Application Communication). The IOC is based on the principles of (queued / unqueued) messages and can be used from the RTE, to give an example.
- For synchronization between basic software (BSW) modules or complex device drivers (CDD), spinlocks were introduced.
After the first practical experiences in projects that use multicore microcontrollers (MCU), it is clear that the major challenge for AUTOSAR projects is the mapping of applications and basic software to the different cores. The mapping decides whether it is possible to use the full performance of such a multicore MCU or performance is wasted.
The paper “Load balancing in AUTOSAR multicore systems“, describes various approaches towards the mapping of applications as well as the pros and cons of each method. The authors of the paper are Dr. Kathrin Danielle Scheidemann and Michael Knapp with BMW Car IT GmbH as well as Claus Stellwag with EB (Elektrobit).
Read the complete paper at elektroniknet.de (German language).
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