一种新型高效共享的并行I/O系统

如何有效地解决I／O瓶颈问题，一直是高性能并行计算机有待解决的关键技术。该文提出了一种高效共享的并行I／O系统——HPPIO，该系统基于CC-NUMA并行系统结构，采用了一系列高效共享、并行I／O技术。该文对其分布与集中相结合的高效共享并行I／O系统结构、基于PCI Express的高性能I／O控制器设计等进行了介绍。     

利用缓冲区提高Java应用程序的I／O性能

Java语言的跨平台特性使得其在各个领域得到了广泛应用。与此同时，Java应用程序的性能，特别是I／O性能，也是人们普遍关注的话题。本文采用一个生物信息学应用程序的实例来探讨如何利用I／O缓冲区提高Java应用程序的I／O性能。我们采用三种不同的I／O缓冲区的实现方式来实现该应用程序，对其进行性能分析比较并将其与相应的C＋＋应用程序进行比较。大量实验表明，I／O缓冲区对于Java应用程序的I／O性能起着至关重要的作用。恰当地使用I／O缓冲区，某些场合下能使Java应用程序的I／O性能略高高于相应的C＋＋应用程序的I／O性能。     

I/O的实施

在设备自动化升级过程中．置换I／O连接通常被看作是一种最基本的设备升级。设备内部I／O系统能够减少制造过程与控制系统之间因置换I／O连接而带来的不便。而且．在某些情况下．I／O系统甚至能够成为控制系统。     

网络编程中各种I/0方式的比较与选择

本文以UNIX系统下ech0服务的编程实现为例,系统介绍各种I/O方式的特点.通过对比各种I/O方式的特点,探讨在实际应用中如何选取最优的I/O方式,并给出一个通用的I/O方式选择标准.     

利用FactorySuite 2000 I/O Server Toolkt开发I/O Server

本文介绍了利用美国WONDERWARE公司的Wonder-wareR FactorySuiteTM 2000 I/O Server Toolkit如何开发用户自己的I/O Server.     

利用FactorySuite 2000I/O Server Toolkit开发I/O Server

本文介绍了利用美国WONDERWARE公司的Wonder-ware FactorySuiteTM 2000 I/O Server Toolkit如何开发用户自己的I/O Server。     

水泥生产线上PCS7系统集中和分布式I/O扩展

PCS7近年来在新型干法水泥生产线DCS系统中得到了广泛应用。PCS7与过程信号的连接有两种方式：集中式I／O扩展和分布式I／O扩展,目前这两种方式在新型千法水泥生产线上都有应用,相对而言,分布式I／O扩展在新型干法水泥生产线上具有更大的优势。     

Optimizing I/O server placement for parallel I/O on switch-based irregular networks

In this paper, we study I/O server placement for optimizing parallel I/O performance on switch-based clusters, which typically adopt irregular network topologies to allow construction of scalable systems with incremental expansion capability. Finding optimal solution to this problem is computationally intractable. We quantified the number of messages travelling through each network link by a workload function, and developed three heuristic algorithms to find good solutions based on the values of the workload function. The maximum-workload-based heuristic chooses the locations for I/O nodes in order to minimize the maximum value of the workload function. The distance-based heuristic aims to minimize the average distance between the compute nodes and I/O nodes, which is equivalent to minimizing average workload on the network links. The load-balance-based heuristic balances the workload on the links based on a recursive traversal of the routing tree for the network. Our simulation results demonstrate performance advantage of our algorithms over a number of algorithms commonly used in existing parallel systems. In particular, the load-balance-based algorithm is superior to the other algorithms in most cases, with improvement ratio of 10 to 95% in terms of parallel I/O throughput.     

I/O受限的并行加速比模型与可扩展I/O体系结构

为了缓解I/O瓶颈问题,可以从应用程序、可扩展算法、编译器和语言、运行时库、操作系统和体系结构六方面展开研究。其中,I/O体系结构是所有技术途径的关键支撑。当前并行I/O性能分析缺乏科学的理论模型为I/O体系结构设计提供理论依据。本文针对并行计算机系统的可扩展性问题,研究了I/O负载对并行计算机系统可扩展性的影响,建立了I/O受限的并行加速比性能模型,对目前大规模并行计算机系统中三种常用I/O体系结构的可扩展性进行了分析;以此为理论依据,提出了一种面向高性能计算的可扩展并行I/O系统结构。同时,还提出了几种有效降低I/O操作服务时间的策略,从而达到增强系统可扩展性的目的,为后续研究奠定了基础。     

基于单根I/O虚拟化的多根I/O资源池化方法

虚拟化技术在为现代数据中心提供高效的服务器整合能力和灵活的应用部署能力的同时,也对数据中心服务器的I/O系统设计提出了新的需求,现有I/O资源与服务器紧密绑定的I/O体系架构将产生成本上升、资源冗余、I/O连线复杂化等一系列问题.针对上述问题,提出了一种基于单根I/O虚拟化协议(single root I/O virtualization, SR-IOV)的多根I/O资源池化方法：基于硬件的多根域间地址和ID映射机制,实现了多个物理服务器对同一I/O设备的共享复用,有效减少单体服务器所需的设备数量和连线数量,并进一步提高服务器密度;同时提出虚拟I/O设备热插拔技术和多根共享管理机制,实现了虚拟I/O资源在服务器间的实时动态分配,提高资源的利用效率.提出的方法在可编程逻辑器件(fieid-programmable gate array, FPGA)原型系统中进行了验证,其评测表明,方法能够在实现多根I/O虚拟化共享的同时,保证各个根节点服务器获得近乎本地直连设备的I/O性能.     

RocketIO几个关键问题的解决方案

FPGA的内嵌RocketIO模块在实际应用中需要解决时钟不稳及通道绑定同步等问题。通过精心设计DCM单元保证了RocketIO内部时钟的精确。同时,针对通道不同步的问题,设计了一种弹性存储器方案,很好地解决了通道同步接收问题。该方案在863重大课题“可扩展到T比特的高性能IPv4/v6路由器基础平台及实验系统”中得到了验证。     

Using eager strategies to improve NFS I/O performance

Typical network file system (NFS) clients write lazily: they leave dirty pages in the page cache and defer writing to the server. This reduces network traffic when applications repeatedly modify the same set of pages. However, this approach can lead to memory pressure, when the number of available pages on the client system is so low that the system must work harder to reclaim dirty pages. We show that NFS performance is poor under memory pressure and present two mechanisms to solve it: eager writeback and eager page laundering. These mechanisms change the client's data management policy from lazy to eager, in which dirty pages are written back proactively, resulting in higher throughput for sequential writes. In addition, we show that NFS servers suffer from out-of-order file operations, which further reduce performance. We introduce request ordering, a server mechanism to process operations, as much as possible, in the order they were sent by the client, which improves read performance substantially. We have implemented these techniques in the Linux operating system. I/O performance is improved, with the most pronounced improvement visible for sequential access to large files. We see 33% improvement in the performance of streaming write workloads and more than triple the performance of streaming read workloads. We evaluate several non-sequential workloads and show that these techniques do not degrade performance, and can sometimes improve performance.     

Reducing I/O variability using dynamic I/O path characterization in petascale storage systems

In petascale systems with a million CPU cores, scalable and consistent I/O performance is becoming increasingly difficult to sustain mainly because of I/O variability. The I/O variability is caused by concurrently running processes/jobs competing for I/O or a RAID rebuild when a disk drive fails. We present a mechanism that stripes across a selected subset of I/O nodes with the lightest workload at runtime to achieve the highest I/O bandwidth available in the system. In this paper, we propose a probing mechanism to enable application-level dynamic file striping to mitigate I/O variability. We implement the proposed mechanism in the high-level I/O library that enables memory-to-file data layout transformation and allows transparent file partitioning using subfiling. Subfiling is a technique that partitions data into a set of files of smaller size and manages file access to them, making data to be treated as a single, normal file to users. We demonstrate that our bandwidth probing mechanism can successfully identify temporally slower I/O nodes without noticeable runtime overhead. Experimental results on NERSC’s systems also show that our approach isolates I/O variability effectively on shared systems and improves overall collective I/O performance with less variation.     

I/OTrace收集器的设计

对I/O Trace收集器的总体设计方案进行了阐述,同时简述了I/O Trace收集器的工作原理:过滤驱动截获对磁盘的操作,得到读写磁盘的起始扇区以及扇区数并将这些信息保存到链表中;通过建立系统线程,不停的从链表中获取信息;最后将这些信息记录到该收集器自身所创建的日志文件中去;用户控制程序部分,实现对不同分区的记录。     

Microprocessor I/O emulation facilities

Many microprocessor emulation systems provide little or no I/O facilities for the processor being emulated. It is assumed that the user already has some target hardware which will provide these. However, this is often not the case, especially in the early stages of a project. An interface which may be used with a 68000 or a 6800 microprocessor emulator to provide a selection of I/O facilities is described. In conclusion, similar more flexible facilities that could be provided by microprocessor development systems manufacturers are indicated.     

PROFINET I/O总线诊断

使用PROFINET总线连接PROFINET I/O设备(站点)时,如果某个总线站点出现故障或掉线,设备还在继续运行的话,这时该设备及其周围人员都将处于非常危险的状态,一旦设备出现误动作,将导致严重的生产事故。对于总线的实时状态,必须在程序中进行判断,故障的站点号必须及时被读出,这样PLC才能根据总线故障信息,快速进行保护性的输出,甚至停止输出,使设备运行处于安全状态。因此,对PROFINET总线状态的诊断具有非常重要的实际意义。诊断总线站点故障的方法有多种,本文重点介绍两种读取PROFINET总线状态到用户程序中的方法,并对这两种方法如何通过用户程序实现做详细说明。