Comment 1 for bug 1576600

It appears Xorg uses CLOCK_MONOTONIC_COARSE for its (input) timestamps. And Mir generally uses CLOCK_MONOTONIC for its input resampling code (via systemTime and libinput). On top of that, a lot of precision is lost in Xorg only keeping millisecond accuracy by design :(

So those two issues probably explain the jerkiness completely, and especially explains why it's only visible when input resampling is active (because that's the only time we need the clocks to match up).

Brandon has also mentioned he has delay issues with key events (which I am not seeing). But that could also be explained by the above timing problems.

We should try to at least convert X's input event timestamps into CLOCK_MONOTONIC in case the epoch and/or frequencies are different. And as a last resort might want to try just synthesising timestamps in the x11 input platform.