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Linux latency measurements and compositor tuning [KWin Wayland]

22 points by Joe_Cool

by ahartmetz

1 subcomments

These latency numbers all look terrible to me tbh. I got better latency numbers (a little over 2 frames in KWrite, close to the theoretical minimum with X11 compositing) with an AMD GPU w/ open drivers, KWin, X11 and compositing enabled a couple of years ago. Measured with high fps recording on a phone camera filming keyboard and screen. Both Wayland and KWin changes should have improved the situation since then. I suspect the games, the screen and / or the graphics drivers which are presumably "review optimized" for frame rate over latency.
Actionable advice from the article: Using Wayland natively from Wine does seem to help, especially against latency jitter / for consistent frame pacing, which is a typical improvement for Wayland.

by Joe_Cool

1 subcomments

Interesting methodology:

    "To investigate, I used a small Teensy microcontroller to measure click-to-photon latency. It acts as a USB HID mouse and is paired with a light sensor pressed against the screen. I flashed it with an existing Open Source LDAT sketch, with slight modifications. The resulting setup can log hundreds of samples to a CSV file, unattended."