A mixed criticality system is a system containing computer hardware and

software Software is a set of computer programs and associated software documentation, documentation and data (computing), data. This is in contrast to Computer hardware, hardware, from which the system is built and which actually performs the work. ...

that can execute several applications of different criticality, such as safety-critical and non-safety critical, or of different

Safety Integrity Level Safety integrity level (SIL) is defined as the relative level of risk-reduction provided by a safety function, or to specify a target level of risk reduction. In simple terms, SIL is a measurement of performance required for a safety instrumented ...

(SIL). Different criticality applications are engineered to different levels of assurance, with high criticality applications being the most costly to design and verify. These kinds of systems are typically embedded in a machine such as an aircraft whose safety must be ensured.

Principle

Traditional safety-critical systems had to be tested and certified in their entirety to show that they were safe to use. However, many such systems are composed of a mixture of safety-critical and non-critical parts, as for example when an aircraft contains a passenger entertainment system that is isolated from the safety-critical flight systems. Some issues to address in mixed criticality systems include real-time behaviour, memory isolation, data and control coupling. Computer scientists have developed techniques for handling systems which thus have mixed criticality, but there are many challenges remaining especially for multi-core hardware.

Priority and Criticality

Basically, most errors are currently committed when making confusion between priority attribution and criticality management. As priority defines an order between different tasks or messages to be transmitted inside a system, criticality defines classes of messages which can have different parameters depending on the current use case. For example, in case of car crash avoidance or obstacle anticipation, camera sensors can suddenly emit messages more often, and so create an overload in the system. That is when we need to make Mixed-Criticality operate : to select messages to absolutely guarantee on the system in these overload cases.

Research projects

EU funded research projects on mixed criticality include:
MultiPARTES

DREAMS

PROXIMA

CONTREX

SAFURE
* CERTAINTY * VIRTICAL * T-CREST
PROARTIS

ACROSS (Artemis)

EMC2 (Artemis)
* RECOMP Artemis
ARAMIS
an
ARAMIS II

IMPReSS
UK EPSRC funded research projects on mixed criticality include:
MCC
Several research projects have decided to present their research results at the EU-funde
Mixed-Criticality Forum

Workshops and Seminars

Workshops and seminars on Mixed Criticality Systems include:
1st International Workshop on Mixed Criticality Systems (WMC 2013)

2nd International Workshop on Mixed Criticality Systems (WMC 2014)

3rd International Workshop on Mixed Criticality Systems (WMC 2015)

4th International Workshop on Mixed Criticality Systems (WMC 2015)

Dagstuhl Seminar on Mixed Criticality on Multicore/Manycore Platforms (2015)

Dagstuhl Seminar on Mixed Criticality on Multicore/Manycore Platforms (2017)

References

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External links

Karlsruhe Institute of Technology: Mixed Criticality in Safety-Critical Systems

Washington University in St Louis: A Research Agenda for Mixed-Criticality Systems
Software engineering Safety engineering