Improving Web Server Performance Through Main Memory Compression

Current web servers are highly multithreaded applications whose scalability benefits from the current multicore/multiprocessor trend. However, some workloads can not capitalize on this because their performance is limited by the available memory and/or the disk bandwidth, which prevents the server from taking advantage of the computing resources provided by the system. To solve this situation we propose the use of main memory compression techniques to increment the available memory and mitigate the disk bandwidth problem, allowing the web server to improve its use of CPU system resources. In this paper we implement to the Linux OS a full SAP capable main memory compression subsystem to increase the performance of a web server running the SPECweb2005 benchmark. Although main memory compression is' not a new technique per-se, its use in a multicore environment running heavily multithreaded applications like a web server introduces new challenges in the technique, such as scalability issues and the trade-off between the compressed memory size and the computational power required to achieve it. Finally, the evaluation of our implementaiton shows promising results such as a 30% web server throughput improvement and a 70% reduction in the disk bandwidth usage.