Hi, On 17 September 2016 at 08:21, Jasper St. Pierre <jstpie...@mecheye.net> wrote: > Daniel suggested that timestamps *should* be on the same timebase. > Currently, they are not. X11 server timestamps are > CLOCK_MONOTONIC_COARSE-based and are calculated at delivery time, evdev > timestamps are CLOCK_MONOTONIC-based and are calculated at input time. This > is why there are several focus management bugs that happen when you replace > meta_display_get_current_time_roundtrip() with a clock_gettime(). > > We need to fix this, otherwise we can never properly synchronize X11 event > streams and Wayland event streams. But Xorg calls GetCurrentTimeMillis() > literally everywhere and compares against that instead of using evdev's own > timestamps, and I doubt we can fix that without breaking multiple, multiple > clients.
Part of this is untrue: a779fda224 back in May made the server use CLOCK_MONOTONIC for GetTimeInMillis, and nothing broke. Secondly, it's not calculated at delivery (ProcessInputEvents) time, but at reception (was-SIGIO-now-thread) time. You're right that we can't move it to the actual event timestamps, but that's true of anything which requires a monotonic timestamp stream in the presence of multiple devices; you'd need to read from all devices upfront, put all their events in a list, then sort that list by timestamp before processing it. I don't believe anyone does that. Either way, you can never do it in the server, because whilst Wayland restricts timestamps to being on separated per-seat timelines, X11 requires a global and queryable time base across multiple domains, not just input. Anyway, point is that unless a compositor is reusing event timestamps, it's just fine, and if it is, it's probably not doing that sort and thus broken anyway. Cheers, Daniel _______________________________________________ xorg-devel@lists.x.org: X.Org development Archives: http://lists.x.org/archives/xorg-devel Info: https://lists.x.org/mailman/listinfo/xorg-devel
