Introduction
If you've transitioned from Windows to Linux, you might have noticed that latency in games can be an issue. This phenomenon is often felt when the mouse seems to "float." For developers and gamers, latency is a crucial factor in a successful user experience. This article guides you through methods to measure this latency on Linux and optimize the compositor.
Why Measure Latency?
Latency, or the delay between an action and its visual reaction, is critical in interactive environments such as games or graphic applications. High latency can degrade the user experience, making interactions slow and frustrating. Measuring this latency helps identify bottlenecks and optimize performance.
Tools for Measuring Latency
To measure latency, a microcontroller like the Teensy is often used, acting as a USB HID mouse coupled with a light sensor. This setup can log hundreds of samples to a CSV file. For example, a modified Teensy configuration serves to measure "click-to-photon latency."
Hardware Configuration Used
Latency tests were conducted on two computers: a desktop and a laptop, both equipped with an Ada-generation RTX card and a Zen 4 CPU. The devices were connected to the same display, an LG C1 at 120 Hz, via HDMI. Application settings were selected to avoid hardware bottlenecks.
Optimizing the Compositor
The compositor plays a crucial role in managing latency on Linux. Using KDE Wayland 6.6.4 combined with MangoHud for FPS limiting has shown promising results. However, managing variables remains complex, and certain configurations can lead to unexpected behaviors.
Common Issues
Some issues, such as V-Sync mode changes not applying immediately, can occur. It is therefore essential to control each variable carefully to obtain accurate measurements.
Synthetic Tests
To quickly validate display settings, a simple test involves using a latency testing tool that displays a black square turning white upon clicking. This test, conducted on a clean Chromium profile, allows simulating input processing and adjusting system settings.
Conclusion
Measuring and optimizing latency on Linux is a complex but essential process to ensure a smooth user experience. By using the right tools and carefully adjusting settings, you can significantly reduce latency.
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