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Computing infrastructure issues in distributed communications systems : a survey of operating system transport system architectures
The performance of distributed applications (such as file transfer, remote login, tele-conferencing, full-motion video, and scientific visualization) is influenced by several factors that interact in complex ways. In particular, application performance is significantly affected both by communication infrastructure factors and computing infrastructure factors. Several communication infrastructure factors include channel speed, bit-error rate, and congestion at intermediate switching nodes. Computing infrastructure factors include (among other things) both protocol processing activities (such as connection management, flow control, error detection, and retransmission) and general operating system factors (such as memory latency, CPU speed, interrupt and context switching overhead, process architecture, and message buffering). Due to a several orders of magnitude increase in network channel speed and an increase in application diversity, performance bottlenecks are shifting from the network factors to the transport system factors.This paper defines an abstraction called an "Operating System Transport System Architecture" (OSTSA) that is used to classify the major components and services in the computing infrastructure. End-to-end network protocols such as TCP, TP4, VMTP, XTP, and Delta-t typically run on general-purpose computers, where they utilize various operating system resources such as processors, virtual memory, and network controllers. The OSTSA provides services that integrate these resources to support distributed applications running on local and wide area networks.A taxonomy is presented to evaluate OSTSAs in terms of their support for protocol processing activities. We use this taxonomy to compare and contrast five general-purpose commercial and experimental operating systems including System V UNIX, BSD UNIX, the x-kernel, Choices, and Xinu
TZC: Efficient Inter-Process Communication for Robotics Middleware with Partial Serialization
Inter-process communication (IPC) is one of the core functions of modern
robotics middleware. We propose an efficient IPC technique called TZC (Towards
Zero-Copy). As a core component of TZC, we design a novel algorithm called
partial serialization. Our formulation can generate messages that can be
divided into two parts. During message transmission, one part is transmitted
through a socket and the other part uses shared memory. The part within shared
memory is never copied or serialized during its lifetime. We have integrated
TZC with ROS and ROS2 and find that TZC can be easily combined with current
open-source platforms. By using TZC, the overhead of IPC remains constant when
the message size grows. In particular, when the message size is 4MB (less than
the size of a full HD image), TZC can reduce the overhead of ROS IPC from tens
of milliseconds to hundreds of microseconds and can reduce the overhead of ROS2
IPC from hundreds of milliseconds to less than 1 millisecond. We also
demonstrate the benefits of TZC by integrating with TurtleBot2 that are used in
autonomous driving scenarios. We show that by using TZC, the braking distance
can be shortened by 16% than ROS
The Design of a System Architecture for Mobile Multimedia Computers
This chapter discusses the system architecture of a portable computer, called Mobile Digital Companion, which provides support for handling multimedia applications energy efficiently. Because battery life is limited and battery weight is an important factor for the size and the weight of the Mobile Digital Companion, energy management plays a crucial role in the architecture. As the Companion must remain usable in a variety of environments, it has to be flexible and adaptable to various operating conditions. The Mobile Digital Companion has an unconventional architecture that saves energy by using system decomposition at different levels of the architecture and exploits locality of reference with dedicated, optimised modules. The approach is based on dedicated functionality and the extensive use of energy reduction techniques at all levels of system design. The system has an architecture with a general-purpose processor accompanied by a set of heterogeneous autonomous programmable modules, each providing an energy efficient implementation of dedicated tasks. A reconfigurable internal communication network switch exploits locality of reference and eliminates wasteful data copies
The thermodynamics of computational copying in biochemical systems
Living cells use readout molecules to record the state of receptor proteins,
similar to measurements or copies in typical computational devices. But is this
analogy rigorous? Can cells be optimally efficient, and if not, why? We show
that, as in computation, a canonical biochemical readout network generates
correlations; extracting no work from these correlations sets a lower bound on
dissipation. For general input, the biochemical network cannot reach this
bound, even with arbitrarily slow reactions or weak thermodynamic driving. It
faces an accuracy-dissipation trade-off that is qualitatively distinct from and
worse than implied by the bound, and more complex steady-state copy processes
cannot perform better. Nonetheless, the cost remains close to the thermodynamic
bound unless accuracy is extremely high. Additionally, we show that
biomolecular reactions could be used in thermodynamically optimal devices under
exogenous manipulation of chemical fuels, suggesting an experimental system for
testing computational thermodynamics.Comment: Accepted versio
Requirements for implementing real-time control functional modules on a hierarchical parallel pipelined system
Analysis of a robot control system leads to a broad range of processing requirements. One fundamental requirement of a robot control system is the necessity of a microcomputer system in order to provide sufficient processing capability.The use of multiple processors in a parallel architecture is beneficial for a number of reasons, including better cost performance, modular growth, increased reliability through replication, and flexibility for testing alternate control strategies via different partitioning. A survey of the progression from low level control synchronizing primitives to higher level communication tools is presented. The system communication and control mechanisms of existing robot control systems are compared to the hierarchical control model. The impact of this design methodology on the current robot control systems is explored
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