Biblio

Dealing with algorithms, which process large amount of similar data by using significant number of small and various sizes of memory allocation/de-allocation in a dynamic yet deterministic way, is an important issue for soft real-time systems designs. In order to improve the response time, efficiency and security of this kind of processing, we propose a software-based memory management method based on hierarchy of shared memory pools, which could be used to replace standard heap management mechanism of the operating system for some cases. Implementation of this memory management scheme can allocate memory through processing allocation/de-allocation requests of required space. Lockable implementation of this model can safely deal with the multi-threaded concurrent access. We also provide the results of experiments, according to which response time of test systems with soft time-bounded execution demand were considerably improved.

Data analytics and telemetry have become paramount to monitoring and maintaining quality-of-service in addition to business analytics. Stream processing-a model where a network of operators receives and processes continuously arriving discrete elements-is well-suited for these needs. Current and previous studies and frameworks have focused on continuity of operations and aggregate performance metrics. However, real-time performance and tail latency are also important. Timing errors caused by either performance or failed communication faults also affect real-time performance more drastically than aggregate metrics. In this paper, we introduce redundancy in the stream data to improve the real-time performance and resiliency to timing errors caused by either performance or failed communication faults. We also address limitations in previous solutions using a fine-grained acknowledgment tracking scheme to both increase the effectiveness for resiliency to performance faults and enable effectiveness for failed communication faults. Our results show that fine-grained acknowledgment schemes can improve the tail and mean latencies by approximately 30%. We also show that these schemes can improve resiliency to performance faults compared to existing work. Our improvements result in 47.4% to 92.9% fewer missed deadlines compared to 17.3% to 50.6% for comparable topologies and redundancy levels in the state of the art. Finally, we show that redundancies of 25% to 100% can reduce the number of data elements that miss their deadline constraints by 0.76% to 14.04% for applications with high fan-out and by 7.45% up to 50% for applications with no fan-out.

Networks are complex and prone to bugs. Existing tools that check configuration files and data-plane state operate offline at timescales of seconds to hours, and cannot detect or prevent bugs as they arise. Is it possible to check network-wide invariants in real time, as the network state evolves? The key challenge here is to achieve extremely low latency during the checks so that network performance is not affected. In this paper, we present a preliminary design, VeriFlow, which suggests that this goal is achievable. VeriFlow is a layer between a software-defined networking controller and network devices that checks for network-wide invariant violations dynamically as each forwarding rule is inserted. Based on an implementation using a Mininet OpenFlow network and Route Views trace data, we find that VeriFlow can perform rigorous checking within hundreds of microseconds per rule insertion.