基于RT-Linux的数控系统进程间通信方式的研究

为了提高数控系统进程间的通信性能,提出一种用于用户空间进程和内核空间进程间高效通信的方法,该方法有机结合了RT-Linux提供的mbuff和实时FIFO,可有效减少数据拷贝,并彻底避免对是否有新数据到来的轮询监测等额外操作,从而获得较高的通信效率.已在我们开发的数控系统中得到实际应用,取得了满意的效果.     

Hybrid MPI-thread parallelization of adaptive mesh operations

Many of the world’s leading supercomputer architectures are a hybrid of shared memory and network-distributed memory. Such an architecture lends itself to a hybrid MPI-thread programming model. We first present an implementation of inter-thread message passing based on the MPI and pthread libraries. In addition, we present an efficient implementation of termination detection for communication rounds. We use the term phased message passing to denote the communication interface based on this termination detection. This interface is then used to implement parallel operations for adaptive unstructured meshes, and the performance of resulting applications is compared to pure MPI operation. We also present new workflows enabled by the ability to vary the number of threads during runtime.     

HARTEX—a safe real‐time kernel for distributed computer control systems

A hard real‐time kernel is presented for distributed computer control systems (DCCS), highlighting a number of novel features, such as integrated scheduling of hard and soft real‐time tasks as well as tasks and resources; high‐performance time management supporting safe DCCS operation in a hard real‐time environment; synchronization and communication featuring event notification via vector semaphores and transparent communication through implicit (content‐oriented) message addressing. Conventional queues have been substituted by Boolean vectors and vector processing techniques throughout the kernel, resulting in efficient and highly deterministic behaviour, which is characterized by very low overhead and constant execution time of kernel operations, independent of the number of tasks involved. Copyright © 2001 John Wiley & Sons, Ltd.     

Linux共享内存的研究与实现

对于多用户、多任务的操作系统,进程间的通信是非常重要的,它是使整个系统得以有条不紊运作的基础。Linux系统提供了多种IPC机制,如信号、管道、信号量、消息队列、共享内存和套接字等,其中以共享内存效率最高。系统地阐述了Linux共享内存的原理和相关API,并给出了通过System V共享内存通信的实例。     

一种改进的共享存储通信机制

在操作系统的设计和实现中,并享存在是一种普遍采用的进程通信机制。目前的实现中,大多是将共享存储区放于用户空间中,并随着程序运行的需要而动态的创建、附接、断接和撤消共享区,并对其进行换入／换出等操作。这些操作引入了较多的额外开销,影响了进程通信的效率。另一方面,在目前的实现中,对共享区中中空间的管理和使用缺乏灵活性。本文提出了一种使用核心中固定区域作为共享存储区来实现进程间通信的方法,并对共享区中空     

Unix System VIPC及共享内存机制分析

介绍了Unix System VIPC(InterProcessCommumication) 及其享内存区的通信机制,以及IPC机制与Unix内核之间的关联,最后给出应用实例,共享内享区在电子公告板BBS系统上的实现。     

Architectural Support and Mechanisms for Object Caching in Dynamic Multithreaded Computations

High-level parallel programming models supporting dynamic fine-grained threads in a global object space are becoming increasingly popular for expressing irregular applications based on sophisticated adaptive algorithms and pointer-based data structures. However, implementing these multithreaded computations on scalable parallel machines poses significant challenges, particularly with respect to object caching. Object caching techniques must be able to tolerate unresponsive processors and protocol handler occupancy delays. This paper examines whether these challenges can be offset by leveraging responsive general-purpose communication architectural features (such as remote memory access and atomic operations), possibly compensating for the lack of more sophisticated hardware primitives by relying upon increased involvement of the run-time system and the compiler. A detailed performance analysis of four irregular applications, using the Illinois Concert System on the Cray T3D and the SGI Origin 2000, finds that existing software distributed shared memory (DSM) systems are capable of delivering good performance only in the presence of a high level of responsive communication architecture support (specifically, support for remote atomic operations). Recognizing that this situation stems from the synchronous request–reply nature of DSM protocols, we present a composable object caching framework, called view caching, which exploits knowledge of application data access semantics to construct custom protocols that require reduced processor synchronization. View caching protocols are more tolerant to responsiveness and occupancy delays and are able to exploit even lower level responsive communication primitives (such as nonatomic remote memory accesses) for a performance benefit.     

In-kernel integration of operating system and infiniband functions for high performance computing clusters: a DSM example

The infiniband (IB) system area network (SAN) enables applications to access hardware directly from user level, reducing the overhead of user-kernel crossings during data transfer. However, distributed applications that exhibit close coupling between network and OS services may benefit from accessing IB from the kernel through IB's native verbs interface, which permits tight integration of these services. We assess this approach using a sequential-consistency distributed shared memory (DSM) system as an example. We first develop primitives that abstract the low-level communication and kernel details, and efficiently serve the application's communication, memory, and scheduling needs. Next, we combine the primitives to form a kernel DSM protocol. The approach is evaluated using our full-fledged Linux kernel DSM implementation over infiniband. We show that overheads are reduced substantially, and overall application performance is improved in terms of both absolute execution time and scalability relative to an entirely user level implementation.