Processing Strategy Research Based On Alternative/compensation Real-time Transaction

In support Alternative/compensation real-time Transaction Model ACTM (theAlternative Compensate Transaction Model), the Alternative one increase the adaptiveability of the Transaction one, while Compensate one can eliminate the external impactof firms. Based on ACTM transaction model, people has made great progress onresearch about related transaction, including: transaction analysis beforehand,transaction admission control mechanism, transaction scheduling and transactionconcurrency control mechanism, etc. The paper on the basis of this, the paper has studyACTM transactions continue to transaction (alternative) priority assignment, the systemof admission control mechanism, transaction concurrency control and schedulingpolicies are key issues. Specific content includes the following aspects.(1)Transaction priority assignment strategy based on value density and urgency. Inview of the ACTM transaction model, considering the transaction relationship withAlternative, puts forward the Priority dispatching strategy Based on Alternative PBAC(Priority-the assignment on the Alternative and Compensation), give full considerationto replace the value of density, pressing related, and execution of business degrees.(2) System admission control strategy under overload. For periodic real-timetransaction in order to improve the the systems success rate and resource utilization,overload management strategy OMS (Overload Management Strategy), who died and toseize relationship between the operating system can be a system job is recognized asstable complete the job as well as absolute The mortality job. When the system usesOMS-based scheduling policy, release stable complete the job and refused to absolutemortality job. It solves a problem in the process of cascading seize part of the job cannot get enough of the system resources and mortality, in order to achieve the systemperformance optimization.(3) Conflict processing strategy of hard real-time transaction based on criticalregion partition. Disaster will cause the conflict between hard real-time transactionsystems, the system should focus on prevention. According to the characteristics of thealternative access to the data object will replace is divided into several Critical region,Critical region dynamic compatibility testing method is proposed and the concurrencyControl Strategy based on dynamic Critical region compatible COR-CCS (CriticalOperation Regions-Concurrcy Control Strategy), which makes the current Critical region compatible transaction can execute concurrently, enhances the concurrency oftransactions(4) Compensation scheduling policy based on load degree of urgency performed.Compensation task can eliminate the influence of die affairs to the outside world and thecompensation effect is directly associated with compensation of task execution time,compensation is perform tasks in a timely manner; Take up system resourcescompensation, on the other hand, task, and its main task bundle will aggravate theburden of system, this will reduce the success rate of transaction executions. To supportreal-time compensating transaction characteristics, designed a kind of compensationsupport tasks based on task load urgent task scheduling strategy TSCTTL（TaskScheduling for Complement Task Based on Task Load）.Through analysisng the above theoretical, empirical analysis and systemsimulation, obtained the following conclusions:(1) For the alternative priority dispatching, dynamic non-emergency strategy has abetter performance in various load cases. For transaction priority, if only consider theCPU time, highest inheritance system scheduling strategy to get the best performance; Ifthe value of the total system, alternative priority strategy suitable for the system load isbigger, rather than replace the system load is suitable for small; If consider thetransaction success rate and the effective utilization rate of CPU, alternative strategyunder non-emergency static priority choice.(2) Job execution has the choice of it is reasonable to restrict system load, reducethe invalid preemption, reduce the degree of competition for resources, improveresource utilization and the system benefits. HP-OMS through determine the type ofjob, refused to carry out those who couldn’t finish the homework, get systemperformance optimization. HP-OMS main innovation lies in:(1) to solve the overloadsystem take the homework to cascade in phenomenon;(2) the strategy can adapt todynamic scheduling tasks set change.(3) The experimental results show that real-time transaction model and relevantsupport alternative series strategy can significantly enhance the transaction success rate,in different situation has different performance, FHC is helpful to improve the successrate of the hard real-time transactions, however, contribution to the system overalltransaction success rate is not better than the FHC, SP-CCCP and COR-CCS strategy ishelpful to reduce the resource conflicts. (4) When the system is overloaded, compensation task start threshold is closelyrelated to the system workload, the system under a particular workload, there is a value,so using TSCTTL scheduling strategy, system deadline miss rate is lowest, so usingTSCTTL scheduling strategy can reduce the deadline of the system.Compared with the domestic and foreign research in this field, innovation pointsand theoretical contributions of this study is to:(1) PBAC is proposed based on an alternative transaction priority dispatchingstrategy, incorporating the value density and urgency, and make the transactionalternative priority inheritance. PBAC strategy can get better performance of the systemin a dynamic environment.(2) A periodic transaction oriented overload control strategy of HP-OMS, HP-OMSto solve the overload system take the homework to cascade in phenomenon; Thisstrategy can adapt to dynamic scheduling tasks set change.(3) In view of the FATM real-time transaction model, will replace divided intocritical region, compatible to distinguish between static and dynamic, and put forwardthe dynamic compatibility testing method, and the corresponding critical region criticalregion COR-CCS concurrency control strategy, the strategy can achieve a better successrate and the effective utilization rate of CPU system.(4) Gives the real-time tasks in the system relative perform urgent degree, studiedthe real-time task urgent degree of relationship with the waiting time, and discussed thecompensation task of real-time task scheduling time; However TSCTTL schedulingstrategy is put forward, is advantageous to the transaction success rate and the effectiveutilization rate of CPU.