Relax: Automatic Contention Detection and Resolution for Configuration Related Performance Tuning.

As the scale and complexity of software expands, the issue of software performance is attracting increasing attention. The causes of performance problems mainly fall into two categories: software bugs and the resource contention among multiple software programs. Software bugs are usually caused by inefficient or unnecessary computation in source code. However, the performance problems caused by resource contention among multiple software programs are usually ignored by most researchers. Unlike software bugs, resource contention is not a bug; as a result, it is difficult to identify the concrete reason for a performance problem given that they share the same symptoms, such as long response time or low system throughput. In this paper, we investigate the performance problems caused by resource contention from a configuration perspective. By studying the response time distribution of software as the workload changes, we find that there is an inflection point of response time with the change of workload. Based on our observations, we design and implement a tool, Relax, to automatically detect and resolve resource contention. Relax combines resource request delay at the inflection point and the system resource usage rate to identify the performance problems caused by resource contention. Moreover, inspired by the congestion control algorithm in computer networks, Relax uses the square-increase and multiplicative-decrease method to adjust the resource-related configurations so as to resolve the contention. Our experiments show that Relax can effectively detect and resolve resource contention, and shorten the total software response time by 15.8% ~ 22.8%.