Praveen Jayachandran

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— In this work, we address problem determination in virtualized clouds. We show that high dynamism, resource sharing , frequent reconfiguration, high propensity to faults and automated management introduce significant new challenges towards fault diagnosis in clouds. Towards this, we propose CloudPD, a fault management framework for clouds. CloudPD(More)
Many scientific disciplines provide composition primitives whereby overall properties of systems are composed from those of their components. Examples include rules for block diagram reduction in control theory and laws for computing equivalent circuit impedance in circuit theory. No general composition rules exist for real-time systems whereby a(More)
— We have developed an analysis-based design tool, ANDES, for modeling a wireless sensor network system and analyzing its performance before deployment. ANDES enables designers to systematically develop a model for the system, refine it iteratively by tuning the system parameters based on existing analysis techniques, and resolve key design decisions(More)
—This paper develops a software service for dynamic performance optimization and control in performance-sensitive systems. The next generation of performance-sensitive systems is expected to be more distributed and dynamic. They will have multiple " knobs " that affect performance and resource allocation. However, relying on the conglomeration of(More)
A significant problem with no simple solutions in current real-time literature is analyzing the end-to-end schedulability of tasks in distributed systems with cycles in the task graph. Prior approaches including network calculus and holistic schedulability analysis work best for acyclic task flows. They involve iterative solutions or offer no solutions at(More)
Datalink layer framing in wireless sensor networks usually faces a trade-off between large frame sizes for high channel bandwidth utilization and small frame sizes for effective error recovery. Given the high error rates of intermote communications, TinyOS opts in favor of small frame sizes at the cost of extremely low channel bandwidth utilization. In this(More)
Personal instrumentation and monitoring services that collect and archive the physical activities of a user have recently been introduced for various medical, personal, safety, and entertainment purposes. A general software architecture is needed to support different categories of such monitoring services. This paper presents a software architecture,(More)
This paper presents the delay composition algebra: a set of simple operators for systematic transformation of distributed real-time task systems into single-resource task systems such that schedulability properties of the original system are preserved. The transformation allows performing schedulabil-ity analysis on distributed systems using uniprocessor(More)
Uniprocessor schedulability theory made great strides, in part, due to the simplicity of composing the delay of a job from the execution times of higher-priority jobs that preempt it. In this paper, we bound the end-to-end delay of a job in a mul-tistage pipeline as a function of job execution times on different stages under pre-emptive as well as(More)