用CMT技术加速虚拟化——访Sun公司大中华区企业系统事业部总监吴坚申

借助CMT(芯片多线程)技术,Sun将不断强化其处理器的并行多线程处理能力,让它与Solaris操作系统搭配,为虚拟化技术及应用的推进提供更好的性能支持。     

OpenCMP：一个支持事务存储模型的多核处理器模拟器

CPU设计正在由仅开发指令级并行性的单线程单核结构转向利用线程级并行性的多线程多核结构，但至今还没有一个可移植性好并被广泛使用的开源多核处理器模拟器，限制了在这样的结构上开展高质量的研究工作。我们开发了一个多核处理器体系结构模拟器OpenCMP，用于支持当前和未来对多线程多核处理器体系结构关键技术的研究。该模拟器适当地抽象了多核处理器结构，为主流的多核处理器结构研究提供一个可扩展、灵活的模拟工具框架，包括支持对乱序、顺序的处理器核和同时多线程处理器核的模拟，以便对更大的多核设计空间进行比较性研究。本文以支持事务存储模型的多核处理器结构模拟器为例，详细描述了如何通过抽象多核结构和事务存储模型的最基本特性和组成部分，扩展单核处理器模拟器SimpleScalar，设计与实现一个多核处理器模拟器。初步研究表明，与现有的多核处理器模拟器相比，该模拟器能够较好地支持对事务存储模型和基于事务存储模型的多核处理器体系结构的研究．     

多核多线程结构线程调度策略研究

片上多核多线程（CMT）结构兼具了片上多处理（CMP）和同时多线程（sMT）结构的优势，支持片上所有处于执行状态的线程每周期并行执行，导致核内与核间硬件资源共享和争用问题。该文在阐述CMT结构的资源共享特征并简要介绍SMT线程调度发展状况的基础上，主要围绕以减少资源争用为目标的线程调度策略和资源划分机制等热点，分析其研究现状，论述已有策略在处理这些问题上的优缺点，并探讨了可能的研究发展方向。     

芯片级多线程处理器的操作系统调度研究

随着芯片级多线程（CMT）处理器体系结构的迅速发展,操作系统必须采用新型CMT调度,以发挥其体系结构的性能优势。分析CMT调度面临的问题,通过扩展调度域的层次和结构支持CMT处理器内部的负载均衡,利用协同调度避免cache抖动等问题。采用效率、效率瓦特比和公平性等多种指标对操作系统进行性能评价,证明其性能得到优化。     

服务器大观

Sun免费公布T1处理器设计要点3月27日,Sun Microsystems公司宣布,它将公布UltraSPARC T1处理器的硬件设计要点和Solaris10操作系统移植技术规范,这是旨在创建全球第一个多核、多线程的绿色系统的“OpenSPARC计划”执行中的一个重大举措。UltraSPARC T1处理器的设计源代码将在OSI(开放源代码促进会)的GNU GPL(通用公共许可)下公布,以使硬、软件开发人员能够采用UltraSPARC T1处理器所特有的芯片多线程(CMT)技术。UltraSPARC T1设计的新的开源版本将被称为“OpenSPARC T1”,这一64位、32线程的处理器的设计要点将免费…     

Sun继续扩展芯片多线程技术优势

面对网络计算的新环境和新挑战,日前,Sun公司宣布,它正在全力推进芯片多线程(CMT)技术的创新。公司计划在2007年的下半年出台基于其64线程的“Niagara 2”处理器系统,同时,Sun公司已经完成它的高端“Rock”处理器的Tapeout阶段(完成设计交付制造),使芯片多线程技术从海量吞吐应用,扩展到数据密集型应用,从而使绿色技术覆盖范围更加广泛。     

并行计算应用程序开发（上）

当今的软件开发是由两个关键因素所促成的:其一是并行计算技术的广泛采用;其二是面向服务的体系结构的发展趋势。这两种理念都由来已久,但当前的CMT(Chip Multi- Threading,芯片多线程)处理器设计、平行扩展系统,延迟时间近乎于零的互连和新的Web服务标准都加速了两     

IXP2400网络处理器架构下防火墙的设计

针对传统设计在防火墙高速度与高灵活性需求上的难以兼顾,给出一个基于Intel IXP2400网络处理器的系统设计方案,借助网络处理器硬件上的微引擎多线程并行处理能力以及软件上对层次型、模块化编程框架的支持,使防火墙系统结合了性能与功能两方面的优势。     

网络互连多线程处理器

结合可扩展的片上互连网络和隐藏延迟的同时多线程结构,论文提出网络互连多线程(NMT,NetworkedMulti-threaded)处理器结构;在SMTSIM仿真器的基础上进行仿真,结果表明NMT结构具有较好的可扩展性和并行性,并提出了对其片上互连网络的性能要求。     

风河与Sun联合推出基于UltraSPARC（R）T2处理器的电信级Linux平台

风河系统公司（Wind River）与Sun微系统公司在全球嵌入式系统大会（Embedded Systems Conference）上联合宣布,风河将面向Sun Ultra SPARC T2芯片多线程（CMT）处理器推出特别定制的电信级Linux（CGL）和Workbench开发套件。Wind River Platform for Network Equipment．Linux Edition将成为首个基于Sun公司CMT处理器的电信级Linux平台。     

A continuation-based noninterruptible multithreading processor architecture

Current trend of research on multithreading processors is toward the chip multithreading (CMT), which exploits thread level parallelism (TLP) and improves performance of softwares built on traditional threading components, e.g., Pthread. There exist commercially available processors that support simultaneous multithreading (SMT) on multicore processors. But they are basically based on the conventional sequential execution model, and execute multiple threads in parallel under the control of OS that handles interruptions. Moreover, there exist few languages or programming techniques to utilize the multicore processors effectively. We are taking another approach to develop a multithreading processor, which is dedicated to TLP. Our processor, named Fuce, is based on the continuation-based multithreading. A thread is defined as a block of sequentially ordered instructions which are executed without interruption. Every thread execution is triggered only by the event called continuation. This paper first introduces the continuation-based multithread execution model and its processor architecture then gives multithreaded programming techniques and the continuation-based multithreading language system CML. Last, the performance of the Fuce processor is evaluated by means of the clock-level software simulation.     

High-performance throughput computing

CMT processors offer a way to significantly improve the performance of computer systems. The return on investment for multithreading is among the highest in computer microarchitectural techniques. If you design a core from scratch to support multithreading, gains as high as 3/spl times/ are possible for just a 20 percent increase in area. Even with throughput performance as the main target, we have shown that the microarchitecture necessary to support threads on a CMT can also achieve high single-thread performance. Hardware scouting, which Sun is implementing on the Rock microprocessor, can increase the single-thread performance of applications by up to 40 percent. Alternatively, scouting is a technique that makes the on-chip caches appear much larger, performance robustness technique, making up for code tailored for different on-chip cache sizes or even a different number and levels of caches.     

A chip multithreaded processor for network-facing workloads

Throughput computing is based on chip multithreading processor design technology. In CMT technology, maximizing the amount of work accomplished per unit of time or other relevant resource, rather than minimizing the time needed to complete a given task or set of tasks, defines performance. By CMT standards, the best processor accomplishes the most work per second of time, per watt of expended power, per square millimeter of die area, and so on (that is, it operates most efficiently). The processor described is a member of Sun's first generation of CMT processors designed to efficiently execute network-facing workloads. Network-facing systems primarily service network clients and are often grouped together under die label "Web servers". The processor's dual-thread execution capability, compact die size, and minimal power consumption combine to produce high throughput performance per watt, per transistor, and per square millimeter of die area. Given the short design cycle Sun needed to create the processor, the result is a compelling early proof of the value of throughput computing.     

Performance of Scheduling Strategies for Client–Server Systems

Two approaches to the improvement of the performance of client–server systems, multithreading and scheduling of servers, are investigated. Both of these approaches are observed to have a significant impact on system performance. The use of multithreading improves throughput characteristics of systems, whereas the deployment of appropriate scheduling strategies at servers can produce a significant improvement in mean client response times. Based on a simulation model a number of basic questions that are important in the context of scheduling on nonmultithreaded, as well as multithreaded, systems are analyzed. Two important factors, monopolization of servers by large requests and software bottlenecks, are observed to be important in the context of scheduling on client–server systems. Both server scheduling, as well as multithreading, can be used to control these effects and lead to a higher system performance. Scheduling policies based on request characteristics are observed to perform well. A new request characteristic that is useful in the scheduling of client–server systems in the presence of software bottlenecks is proposed. Selection of both the server process, as well as the thread within the server, is required when multiple server, are co-located on the same CPU. A comparison between two scheduling approaches, single level and two level is presented in the paper. The results of this research are useful primarily in the design of operating systems for client–server systems and are also of interest to system designers and users.     

多线程技术的现状与前景展望

这几年,多线程计算机得到了较大的发展,也得到了越来越多的关注。本文在分析了多线程概念以及多线程计算机发展历史后,对多线程计算机的研究和开发现状、技术途径发展前景进行了较为系统的介绍,并对其中的关键技术问题展开了探讨。     

A Study of the EARTH-MANNA Multithreaded System

Multithreaded architectures have been proposed for future multiprocessor systems. However, some open issues remain. Can multithreading be supported in a multiprocessor so that it can tolerate synchronization and communication latencies, with little intrusion on the performance of sequentially-executed code? How much does such support contribute to scalable performance when communication and synchronization demands are high? In this paper, we describe the design of EARTH, an architecture which addresses these issues. Each processor in EARTH has an off-the-shelf Execution Unit (EU) for executing threads, and an ASIC Synchronization Unit (SU) supporting dataflow-like thread synchronizations, scheduling, and remote requests. In preparation for an implementation of the SU, we have emulated a basic EARTH model on MANNA 2.0, an existing multiprocessor whose hardware configuration closely matches EARTH. This EARTH-MANNA testbed is fully functional, enabling us to experiment with large benchmarks with impressive speed. With this platform, we demonstrate that multithreading support can be efficiently implemented (with little emulation overhead) in a multiprocessor without a major impact on uniprocessor performance. Also, we measure how much basic multithreading support can help in tolerating increasing communication/synchronization demands.     

龙芯2号同时多线程处理器的软硬件接口设计

随着生产工艺的提高,芯片上能集成越来越多的晶体管,多线程技术也逐步成为一种主流的处理器体系结构技术,而多线程处理器的软硬件接口也就成为急需解决的问题.在分析同时多线程的软件需求的基础上,提出龙芯2号同时多线程处理器的软硬件接口协同设计解决方案,给出相应的操作系统实现方案.同时,在Linux 2.4.20的基础上实现了龙芯2号同时多线程处理器相应的操作系统.通过运行SPEC CPU2000等测试程序进行性能评测,充分说明实现软硬件接口的龙芯2号同时多线程处理器极大地提高了多进程负载的性能.分析和设计方案不仅适用于同时多线程处理器,而且对于片内多核处理器的设计也有借鉴作用.     

分布交互式仿真管理系统设计与实现

仿真系统的复杂化及其网络构造的多样化对整个系统的调度管理提出了越来越高的要求.根据软件工程实践,可以运用多线程技术和分层软件结构设计的思想开发仿真调度管理系统的运行管理模块、网络管理模块和数据管理模块,实现异构网络环境下对整个仿真系统的调度管理功能,模块化的设计方法使得软件有很好的移植性和扩展性.     

Exploiting concurrency in the implementation of a discrete event simulator

Technological improvements in the use of computers through the better management of multithreading, such as with multi-core computers (core duo, core 2 duo, core 2 quad), have resulted in a reassessment of systems for simulating discrete events which can exploit these new capabilities. We consider the design and implementation of a process-oriented discrete event simulation library which makes exhaustive use of concurrence to improve the efficiency with which the simulations are executed.     

多线程模拟电梯运行算法

电梯的运行模拟,是计算机控制教学中的重要素材。模拟方法主要分为硬件模拟和软件模拟,硬件模拟是以单片机为核心,辅以相关硬件和控制程序来实现;软件模拟则是以软件全程模拟电梯系统,包括用户界面和电梯的控制。文中主要探讨了在VC环境下,实现软件模拟电梯运行的算法设计和程序实现,实验证明,堆栈和多线程技术是软件模拟电梯运行的有力工具。