Hard numbers in the Wayland vs X11 input latency discussion - Mort's Ramblings
mort.coffee

I don’t think he should have included the starting frame-- if the cursor were theoretically instant, his method records it with a 1 frame delay, and this +1 frame error happens on every test. Correcting this actually makes Wayland more laggy proportionally, although it makes both less laggy absolutely.

  • @A_AEnglish
    7•3 days ago

    Latency raw data :

    Gnome Variant Δ camera frames Average (Δ) Δ milli seconds Δ monitor refreshes
    X11 5 4 3 4 5 4 6 5 1 4 4 4 3 4 4 4 4.00 16.7 2.4
    Wayland 6 5 6 5 5 6 6 4 8 6 5 5 5 6 5 6 5.5625 23.2 3.3
    Δ(Δ) - - ~1.5 ~6.5 ~1.0

    instead of calculating the average one could decide to drop the data points that are way outside of their goups.
    Doing so, in the first group I would neglect the value of Δ = 1 or 6 frame and in the second group I would neglect the value of 4 or 8 frames

    Results :
    X11 : from 3 to 5 frames
    Wayland : from 5 to 6 frames
    Δ(Δ) = 5.5 - 4 = 1.5

    Still it doesn’t change the final result that the difference between these two Gnome versions is 1.5 camera frames at 240 frames per second.

      • @A_AEnglish
        2•3 days ago

        Thanks. Also, after a bit of thought, i do believe you are right saying that we should remove one frame of all the raw camera data. … it will, as you say, decrease the absolute values and make Wayland more laggy proportionally, yet, it doesn’t change the absolute difference.