Load balancing issues in automotives

Electronic Control Units (ECUs) are widely used to improve the comfort and reliability of vehicles. It has become the fundamental building block of any automotive subsystem and is interfaced with electro mechanics counterpart. To meet the system wide requirements, these ECUs are interconnected using the communication infrastructure. Although the communication infrastructure in terms of, predominantly, the CAN based vehicle network took its birth to enable ECUs to work in a coordinated manner in order to support system wide requirements, during the past decade, this infrastructure was also viewed as a potential means to incorporate extensibility in terms of addition of newer ECUs which are built for implementing additional requirements. With this paradigm, the number of ECUs started growing in a steep manner, uncontrolled and as a result, today, it is not hard to see a high segment automotive housing ECUs as large as 75–80. Hence, load balancing mechanisms are needed to ease ECU integration and for efficient utilization of CPU power in ECUs. In this paper, we explain the concept of load balancing on the basis of CPU utilization across ECUs

Load Balancing towards ECU Integration

There has been an exponential increase in the number of electronic components embedded in vehicles. Development processes, techniques and tools have changed to accommodate that evaluation. A wide range of electronic functions such as navigation, adaptive control, infotainment, traffic information, safety system etc are implemented in today’s vehicles. Many of the new functions are not stand alone and hence they need to exchange information, sometimes with stringent time constraints for time critical functions such as engine management, collision warning systems etc. The complexity of the embedded architecture in a vehicle is continually increasing. Today up to 2500 signals are exchanged through up to 70 Electronic Control Units (ECUs) using 5 different buses. This paper introduces the load balancing approach across ECUs supplied by various Tier1 suppliers

Dynamic Load Balancing in Distributed Content-based Publish/Subscribe ⋆

Abstract. Distributed content-based publish/subscribe systems to date suffer from performance degradation and poor scalability caused by uneven load distributions typical in real-world applications. The reason for this shortcoming is due to the lack of a load balancing solution, which have rarely been studied in the context of publish/subscribe. This paper proposes a load balancing solution specific to distributed content-based publish/subscribe systems that is distributed, dynamic, adaptive, transparent, and accommodates heterogeneity. The solution consists of three key contributions: a load balancing framework, a novel load estimation algorithm, and three offload strategies. Experimental results show that the proposed load balancing solution is efficient with less than 1.5 % overhead, effective with at least 91 % load estimation accuracy, and capable of distributing all of the system’s load originating from an edge point of the network. Keywords: Publish/subscribe, load distribution, content-based routing, load balancing, load estimation, subscriber migration, offloading algorithm

Load Management for Publish/Subscribe Message Oriented Middleware

PhDTo provide time-critical early warnings in a Tsunami Warning System (TWS), the time delay for both the sensor data exchange process (upstream) and the warning message dissemination processes (downstream) should be minimal, maximising the time available for accurately analysing the situation and giving more time for people in the affected region to react to the warnings. Publish/Subscribe Message-oriented Middleware (PSMOM) in combination with a novel use of a federated broker (broker overlay) can be deployed in TWS to support both time-critical and resilient communication. PSMOM can better manage message bursts caused by a sudden increase in sensor data exchange frequency or by additional sensors coming online. PSMOM can better manage the decrease in available system resources (bottlenecks) caused by a disruption in the underlying network infrastructure (limited resource case). Otherwise, these burst and bottlenecks can cause some brokers to become overloaded, which may in turn degrade the overall system performance and delay decision-making. Existing PSMOM load management solutions have two key limitations when applied to TWS. First, existing work does not consider the message delay requirements for the redistribution and offloading phases of load management. Here, some data is only useful or valid for a short time-span (from tens of seconds to tens of minutes); hence, it needs to be exchanged within this maximum allowed end-to-end transmission delay. Time critical subscribers need to be de-prioritised from being offloaded, as the offloading processes take some time to complete, introducing unexpected delays to message exchange. Second, existing solutions assume that there are surplus system resources for offloading, i.e., less loaded brokers can accept loads from overloaded brokers. However, in a TWS, the underlying network infrastructure may be disrupted which in turn reduces the system capacity. It always takes time to recover from the limited resources situation and during that time, brokers may not have enough system resources to accept loads from overloaded brokers, which may result in total failure of the overloaded brokers. A novel load management framework called ePEER is proposed that extends an existing messaging system, Publish/Subscribe Efficient Event Routing (PEER), with the following main contributions. First, for the surplus resource case, the message delay requirements for different subscription services are considered in the load analysis process when offloading the load to different brokers. Second, for the limited resource case, a feedback driven congestion control mechanism can be used when the underlay network infrastructure is damaged, reducing the available bandwidth of PSMOM. This mechanism limits the publication rate of messages with less value, to better maintain the quality of experience (QoE) of subscribers for the more important messages ePEER is validated with emulation-based experiments. The results show that ePEER outperforms the state of the art load management solution used by PEER: through preventing unnecessary delays introduced to time critical services, and through ensuring important messages can be more efficiently exchanged to improve the QoE of subscribers

Management of Temporally and Spatially Correlated Failures in Federated Message Oriented Middleware for Resilient and QoS-Aware Messaging Services.

PhDMessage Oriented Middleware (MOM) is widely recognized as a promising solution for the communications between heterogeneous distributed systems. Because the resilience and quality-of-service of the messaging substrate plays a critical role in the overall system performance, the evolution of these distributed systems has introduced new requirements for MOM, such as inter domain federation, resilience and QoS support. This thesis focuses on a management frame work that enhances the Resilience and QoS-awareness of MOM, called RQMOM, for federated enterprise systems. A common hierarchical MOM architecture for the federated messaging service is assumed. Each bottom level local domain comprises a cluster of neighbouring brokers that carry a local messaging service, and inter domain messaging are routed through the gateway brokers of the different local domains over the top level federated overlay. Some challenges and solutions for the intra and inter domain messaging are researched. In local domain messaging the common cause of performance degradation is often the fluctuation of workloads which might result in surge of total workload on a broker and overload its processing capacity, since a local domain is often within a well connected network. Against performance degradation, a combination of novel proactive risk-aware workload allocation, which exploits the co-variation between workloads, in addition to existing reactive load balancing is designed and evaluated. In federated inter domain messaging an overlay network of federated gateway brokers distributed in separated geographical locations, on top of the heterogeneous physical network is considered. Geographical correlated failures are threats to cause major interruptions and damages to such systems. To mitigate this rarely addressed challenge, a novel geographical location aware route selection algorithm to support uninterrupted messaging is introduced. It is used with existing overlay routing mechanisms, to maintain routes and hence provide more resilient messaging against geographical correlated failures