ITR: Improving the Performance of Web Servers under Overload

本建议的目的是在静态和动态内容的情况下，提供对过载期间服务器行为的深入理解。该方法是跨学科的：有一个理论组件，旨在证明具有时间依赖负载的M/G/1队列的新定理；一个实现组件，它严格系统地研究Web服务器和数据库服务器在不同网络参数下的过载性能；以及一个工作负载和客户端表征组件，其目的是了解瞬时过载期间请求流的统计特性，并将这些统计特性结合到针对过载的Web工作负载生成器的设计中。该建议还引入了一个非常简单的想法来提高过载下Web服务器的性能：基于内核的SRPT连接调度实现。这个想法简单而直观。连接计划不需要购买更多硬件，也不需要任何其他昂贵的系统升级。它似乎允许服务器承受更长时间的过载，并允许客户端在这些过载期间体验更好的性能。此外，它似乎使服务器能够更快地从过载中恢复过来。该提案将详细评估SRPT连接调度的好处，并旨在为数据库引入类似的调度策略。拟议活动产生的更广泛影响包括项目期间产生的所有源代码在线可用，包括对阿帕奇代码和Linux的修改，以及项目期间收集的所有跟踪日志的在线可用，以及针对过载的网络工作量生成器。该项目发起了不同学科的合作，包括：数学、计算机系统和运营管理，以及大学和行业之间的合作。该项目还将为少数族裔本科生提供研究机会。该项目将在3年的课程中涉及1名教员(仅1个暑期月)、1.5名研究生和1名本科生。

This proposal aims to provide this deep understanding of server behavior during overload, in thecase of both static and dynamic content. The approach is interdisciplinary: There is a theoreticalcomponent which aims to prove new theorems on M/G/1 queues with time-dependent load; an implementationcomponent which performs a rigorous systematic study of web server and database serverperformance under overload as a function of various networking parameters; and a workload and clientcharacterization component which aims to understand statistical properties of the request stream duringtransient overload and incorporate these into the design of a web workload generator for overload.This proposal also introduces a very simple idea for improving the performance of web serversunder overload: a kernel-based implementation of SRPT connection scheduling. The idea is simpleand intuitive. Connection scheduling does not require purchasing more hardware, or any other costlysystem upgrades. It appears to allow the server to survive much longer periods of overload, and to allowclients to experience better performance during these periods of overload. Furthermore, it appearsto enable the server to recuperate from overload much faster. The proposal will provide a detailedevaluation of the benefits of SRPT connection scheduling and will aim to introduce similar schedulingpolicies for databases. The above concludes the intellectual merit portion of the proposal.The broader impacts resulting from the proposed activity include online availability of all sourcecode generated during the project including modifications to the Apache code and to Linux, as wellas online availability of all trace logs collected during this project, and a web workload generator foroverload. The project initiates collaborations across various academic disciplines including: mathematics,computer systems, and operations management, as well as between universities and industry.The project will also provide a research opportunity for a minority undergraduate student.The proposal involves 1 faculty member (1 summer month only), 1.5 graduate students, and 1undergraduate, over the course of 3 years.