Virtual-memory-mapped network interfaces

In today's multicomputers, software overhead dominates the message-passing latency cost. We designed two multicomputer network interfaces that significantly reduce this overhead. Both support virtual-memory-mapped communication, allowing user processes to communicate without expensive buffer management and without making system calls across the protection boundary separating user processes from the operating system kernel. Here we compare the two interfaces and discuss the performance trade-offs between them     

用Linux建立高性能的拨号服务器

阐述了如何使用Linux来架设PPP服务器的原理和方法,并讲述了如何实现通过WWW进行密码管理以及计费等。     

Assessing fast network interfaces

Assessing the performance of emerging high-speed networks is difficult. Our communication microbenchmark evaluates design changes in a communications system. Our microbenchmark generates a graphical signature from which we extract communication performance parameters for the hardware-software tandem. We use the LogP conceptual model for communication systems. (LogP stands for the parameters latency, overhead, gap, and processors). We study three important platforms that represent diverse points in the network interface design space: the Intel Paragon, Meiko CS-2, and a cluster of Sparcstation-20s connected by Myrinet switches using LANai SBus cards. Our study views each machine as a gray box supporting Active Messages and conforming to the LogP framework. We devise a simple set of communication microbenchmarks and measure the performance on each platform to obtain the LogP parameters     

用OO方法增强Linux下MySQL数据库的应用性能

介绍用面向对象技术增强Linux下MySQL数据库应用性能的方法，该方法以MySQL提供的C API为基础， 结合实际应用建立面向象类，在连接、会话、安全性、数据完整性等方面提高MySQL的应用性能。     

基于Linux的主机间USB通信的实现*

网络隔离器在隔离了可信网络和不可信网络的同时,允许信息在两个网络间安全传输.主要介绍使用USB实现网络隔离器内部的数据交换.首先介绍了USB系统、USB通信模型和数据传输类型,然后介绍了Linux的USB子系统及主要数据结构,重点说明了使用libusb库实现两台USB主机间的数据传输.     

可扩展的Linux性能监视器

性能监视是系统管理和性能优化的基本手段,然而Linux平台上的性能监视并不能满足系统管理和性能监视的需要。该文用WindowsNT的性能监视器为前端,实现了一个可扩展的Linux性能监视器,它不仅能监视Linux操作系统本身,而且能监视第三方厂商开发的应用程序。     

Linux无线驱动程序的开发测试

针对Linux驱动程序开发缺少快速高效测试手段的问题,提出了精确硬件仿真、实时驱动状态控制和高效数据注入技术,并应用到了无线驱动程序开发实践中。结果证明,该技术能够快速、有效地查找出驱动缺陷,提高驱动程序的可靠性,达到了丰富驱动开发测试手段、加快驱动开发进度的效果。     

Making network interfaces less peripheral

A barrier to delivering improvements in network bandwidth and latency to users is the network interface (NI), which connects a network to the host computer that runs the network software. An NI includes hardware that exposes an internal interface-such as device registers-to a host processor. A key problem with most current NIs is that their internal interface is similar to that of a disk's interface. Because of such limitations, current NIs will not be adequate for use with newer, high-performance networks and host computers. High-performance local area networks have advanced so far that some view them as a new class of networks called system area networks (SANs). Emerging SANs deliver bandwidths of 10 Gbps or more and latencies of tens of nanoseconds-two to four orders of magnitude better than that delivered by most current LANs. New hosts demand much higher performance. If NIs do not adapt to these changes they will become a barrier to improving network performance. To solve this problem, future NIs should appear to their hosts more like memory than disk interfaces. The authors argue that treating NI accesses like memory accesses is justified by the importance of network performance to future computers     

IP-in-IP tunneling to enable the simultaneous use of multiple IP interfaces for network level connection striping

With ubiquitous computing and network access now a reality, multiple network conduits are become widely available to mobile as well as static hosts: for instance wired connections, 802.11 style wireless LANs, Bluetooth, and cellular phone modems. Selection of the preferred mode of data transfer is a dynamic optimization problem which depends on the type of application, its bandwidth/latency/jitter requirements, current network conditions (such as congestion or traffic patterns), cost, power consumption, battery life, and so on. Furthermore, since wireless bandwidth is likely to remain a scarce resource, we foresee scenarios wherein mobile hosts will require simultaneous data transfer across multiple IP interfaces to obtain higher overall bandwidth.We present a brief overview of existing work which enables the simultaneous use of multiple network interfaces and identify the applicability as well as strengths and weaknesses of these related approaches. We then propose a new mechanism to aggregate the bandwidth of multiple IP paths by splitting a data flow across multiple network interfaces at the IP level. We have analyzed the performance characteristics of our aggregation scheme and demonstrate significant gains when the network paths being aggregated have similar bandwidth and latency characteristics. In addition, our method is transparent to transport (TCP/UDP) and higher layers, and allows the use of multiple network interfaces to enhance reliability. Our analysis identifies the conditions under which the proposed scheme, or any other scheme that stripes a single TCP connection across multiple IP paths, can be used to increase throughput.     

Linux内核实时性能改进方案

中断是现代计算机中一项重要的功能。对于具有多个外部设备的计算机系统而言，中断更是不可或缺。Linux内核是一种分时系统，在实时应用方面还有待改进。文章将在分析中断机制的基础上提出一种改进Linux内核实时性能的方案。     

基于RTnet构建具有实时网络的嵌入式Linux系统

在研究EtherCAT协议的过程中,针对传统Linux系统难以满足工业以太网实时性的问题,探索出一种构建具有实时网络的嵌入式Linux系统的方法。采用基于AT91RM9200 ARM9和DM9161网络PHY芯片的硬件平台,利用Xenomai实现嵌入式Linux内核的硬实时性。在此基础上,利用RTnet构建具有实时网络的嵌入式Linux系统,并对该系统进行了网络实时性测试。测试结果表明,该方法在研究基于以太网的实时工业现场总线方面具有较高的工程应用价值。     

Design challenges for high-performance network interfaces

A network interface is a device that allows a computer to communicate with a network. Network interface design has a crucial impact on communication efficiency. It determines the cost of communication actions, moving data, and providing application isolation across communicating domains. With the advent of distributed computing and the Internet, and with dramatically faster processor clock rates and complete systems on chips, computing is increasingly concerned with the efficient movement of data-across the interconnects within a machine, the system area network within a machine room, and the local area or wide area network. The authors discuss network interface design issues     

Memory management for user-level network interfaces

Presents an extension to the U-Net user-level network architecture allows messages to be transferred directly to and from any part of an application's address space without operating system intervention     

Linux update: an experimental ATM network

Both private and public networks increasingly use ATM to provide high bandwidth and guaranteed quality of service. The ability to use Linux in PC platforms and the ready availability of Linux source code make the PC-based Linux workstation an ideal platform for ATM multimedia development. This article describes some of Fujitsu's ATM tools for Linux and reports the results of prototyping using Fujitsu's ATM/Linux development environment     

Linux下编写网络设备驱动程序

网络基本概念及在Linux操作系统下编写网络设备驱动程序的原理、方法和步骤。     

网络安全框架Netfilter在LinuX中的实现

Netfilter是Linux最新版本中的网络防火墙实现，是对以前Linux防火墙版本的完全替换。Netfilter完成了包括包过滤、地址翻译、状态检测、数据包操作等重要功能，是一个结构合理、功能强大、扩展性强的网络安全框架，在研究防火墙的原理、实现上具有重要的借鉴意义。分析和讨论了Linux操作系统的网络安全框架Netfilter的原理和实现。     

基于Linux校园网双出口的实现

当前大多校园网都是通过国家教育网接入的,但通过教育网访问公网速度较慢,不能满足用户的需要.针对此问题提出以Linux为平台用网络双出口解决问题,即当访问教育网时从教育网出口,访问公网时通过当地ISP出口.详细介绍了在Linux下策略路由、NAT技术的原理和具体实现,以及如何将这两个技术相结合实现网络双出口,为需要解决此类问题的用户提供一个切实可行的解决方法.     

Linux操作系统性能评价方法

随着LINUX的发展和普及,受到越来越多人们的青睐。但是由于LINUX的版本繁多,性能各异,如何寻找适合自己的使用的最佳版本也就成了困扰大家的一个问题。本文通过实际测试数据,讲述评价INUX遥方法,从多个角度阐明影响计算机系统性能的因素并分类解释各种不同的测试方法。     

Linux系统实时性能增强技术的研究

本文根据Linux和实时系统的特点，研究了影响Linux实时性能的因素，分析了目前流行的增强标准Linux实时性能的技术。通过从细粒度定时器、内核抢占机制及实时调度策略的深入分析与研究，从不同侧面实现了Linux系统的实时支持，并分析各种实时增强技术的不足与应用领域。     

Linux软件性能分析与优化

为了全面分析Linux系统性能,预测系统潜在的瓶颈问题,首先使用Linux内核动态探测工具SystemTap来采集系统运行时的内核数据,将数据解析后借助Windows平台的可视化工具将解析结果以图形界面的方式输出。通过分析输出结果,可以定位引起系统性能问题的位置和原因,以此对系统做进一步的优化,以达到用户可接受的需求。