There are various tools and techniques that can help you perform proactive or reactive tuning on your OS. Performance monitors, such as Windows Task Manager, Linux top command, or Mac OS Activity Monitor, collect and display data on the system's performance, like CPU usage, memory usage, disk usage, network usage, or process activity. Performance analyzers, like Windows Performance Analyzer, Linux perf command, or Mac OS Instruments interpret and report on the data collected by performance monitors to identify and diagnose performance problems. Lastly, performance optimizers, like Windows System Configuration, Linux sysctl command, or Mac OS System Preferences modify or optimize the system's parameters to improve its performance. These tools can help you measure, analyze, and compare the system's performance over time or under different conditions. They can also provide recommendations or suggestions on how to improve the system's performance and monitor and alert you of any performance issues or changes.