GNOME Mutter Lands New Work To Reduce Input Latency

Long running work by Ivan Molodetskikh to reduce the input latency for GNOME's Mutter compositor was merged today.

The work that landed is around dynamic frame clock dispatch with a focus on reducing the max render time. As part of this work Ivan also added the ability to report the max render time and other information via Clutter when the "CLUTTER_PAINT=max-render-time" environment variable is set.

As for the impact of this latency reduction work: "Difference between maximum and minimum measurement in the same group is usually around ~17.2 ms, which is close to the expected 1000 / 60 = 16.67 ms if application latency was always exactly the same. The difference between median latency of c2968c89 and this MR is ~10 ms for most applications."

This code that was merged is part of a larger effort around automatic frame clock dispatch and frame callback delaying for further lowering input and presentation latency. After being worked on for months, it's great to see the work beginning to land.