基于Myrinet的用户空间精简协议

A Reduced Userlevel Communication Protocol for Myrinet

通信子系统是影响工作站机群系统整体性能的主要因素．文章在分析和比较了３种常用的网络性能之后，指出上层协议的处理是影响工作站机群系统性能的主要瓶颈．在由６４０Ｍｂｐｓ的Ｍｙｒｉｎｅｔ连接的８台ＳｕｎＳＰＡＲＣ工作站组成的机群系统上实现了一个用户层的高性能的精简通信协议——ＲＣＰ（ｒｅｄｕｃｅｄｃｏｍｍｕｎｉｃａｔｉｏｎｐｒｏｔｏｃｏｌ）．通过精简协议的冗余功能、减少数据拷贝次数和直接操作硬件缓冲区等方法，达到低延迟、高效率．ＲＣＰ的回路延迟时间比ＴＣＰ／ＩＰ小得多（２００μｓｖｓ１５４０μｓ），可用带宽也高得多（１７８Ｍｂｐｓｖｓ３４Ｍｂｐｓ），协议的带宽利用率达到８０．５％，并为上层应用程序和ＰＶＭ提供了一个简单。

Communication subsystem is a major factor that affects the overall performance of a workstation cluster system. In this paper, the authors analyzed and compared the performance of three popular networks, and pointed out that the high level protocol processing is the bottleneck of communication in workstation cluster system. A user level high performance protocol, called RCP(reduced communication protocol), had been built on a cluster of 8 Sun SPARC workstations connected with 640Mbps Myrinet. Low overhead and high efficiency of the protocol are achieved by simplifying the protocol's redundant functions, reducing the times of data copying, and operating directly on hardware buffer. The round trip latency of RCP is much lower than TCP/IP(200s vs 1 540s), the application available bandwidth is much improved(178Mbps vs 34 Mbps) and the bandwidth usage of Myrinet on RCP reaches to 80.5%. A very simple interface to application or PVM is provided as well.