Computer Science Technical Reports

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https://hdl.handle.net/1911/94827

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Browsing Computer Science Technical Reports by Author "Amza, Cristiana"

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    Bottleneck Characterization of Dynamic Web Site Benchmarks
    (2002-02) Amza, Cristiana; Cecchet, Emmanuel; Chanda, Anupam; Cox, Alan; Elnikety, Sameh; Gil, Romer; Marguerite, Julie; Rajamani, Karthick; Zwaenepoel, Willy
    The absence of benchmarks for Web sites with dynamic content hasbeen a major impediment to research in this area. We describe three benchmarks for evaluating the performance of Web sites with dynamic content. The benchmarks model three common types of dynamic-content Web sites with widely varying application characteristics: an online bookstore, an auction site, and a bulletin board. For each benchmark we describe the design of the database, the interactions provided by the Web server, and the workloads used in analyzing the performance of the system. We have implemented these three benchmarks with commonly used open-source software. In particular, we used the Apache Web server, the PHP scripting language, and the MySQL relational database. Our implementation is therefore representative of the many dynamic content Web sites built using these tools. Our implementations are available freely from our Web site for other researchers to use. We present a performance evaluation of our implementations of these three benchmarks on contemporary commodity hardware. Our performance evaluation focused on finding andex plaining the bottleneck resources in each benchmark. For the online bookstore, the CPU on the database was the bottleneck, while for the auction site and the bulletin board the CPU on the front-end Web server was the bottleneck. In none of the benchmarks was the network between the front-end and the back-end a bottleneck. With amounts of memory common by today's standards, neither the main memory nor the disk proved to be a limiting factor in terms of performance for any of the benchmarks.
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    Scaling and Availability for Dynamic Content Web Sites
    (2002-06-02) Amza, Cristiana; Cox, Alan; Zwaenepoel, Willy
    We investigate the techniques necessary for building highly-available, low-cost, scalable servers, suitable for supporting dynamic content web sites. We focus on replication techniques for scaling and availability of a dynamic content site using a cluster of commodity computers running Web servers and database engines. Our techniques allow scaling without undue development, maintenance, and installation costs, avoiding modifications to both the Web server and the database engine. Our results on an eight node database cluster show good scaling for the e-commerce TPC-W benchmark provided that suitable load balancing and replication strategies are in place. Key among these strategies is replication with relaxed consistency, in which the server allows controlled internal data inconsistencies to improve performance while hiding these inconsistencies from the user. The actual choice of load balancing strategy is less important. Locality-based load balancing policies based on data caching, found very profitable in static content servers have almost no impact.
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    Scaling e-Commerce Sites
    (2002-02-19) Amza, Cristiana; Cox, Alan; Zwaenepoel, Willy
    We investigate how an e-commerce site can be scaled up from a single machine running a Web server and a database to a cluster of Web server machines and database engine machines. In order to reduce development, maintenance, and installation costs, we avoid modifications to both the Web server and the database engine, and we replicate the database on all database machines. All load balancing and scheduling decisions are implemented in a separate dispatcher. We find that such an architecture scales well for the common e-commerce workload of the TPC-W benchmark, provided that suitable load balancing and scheduling strategies are in place. Key among these strategies is asynchronous scheduling, in which writes complete and are returned to the user as soon as a single instance of the write completes at one of the database engines. The actual choice of load balancing strategy is less important. In particular locality-based load balancing policies, found very profitable for static Web workloads, offer little advantage.