Extremely slow composites with external monitor
First of all, I'm not 100% sure this is the right place to file the issue, so if I should go somewhere else to complain or nothing can be done about it please let me know :)
I'm trying Firefox's Wayland port lately, and it works really great on my laptop when there's no monitor attached, but as soon as I move the window to my external monitor, then I start getting super-slow composites (200ms+), which are pretty bad, to the point that typing becomes hard.
Here's a Firefox profile showing the extremely slow composites (see the "Renderer" thread): https://perfht.ml/2ThSa4v
All of the time is spent under eglSwapBuffers -> wl_display_dispatch_queue (thus the bugfiling here).
I mention Firefox because is the interactive app I use the most, but even
gnome-terminal is slow on the monitor, so I don't think this is Firefox-specific.
This is on a Lenovo P50, with
Mesa DRI Intel(R) HD Graphics P530 (Skylake GT2) and Mesa 19.0.0. Note that my monitor is connected to an external GPU though (
NVIDIA Corporation GM107GLM [Quadro M2000M] (rev a2), which may be part of / all of the problem?).
See https://bug1536678.bmoattachments.org/attachment.cgi?id=9052152 (I just filed https://bugzilla.mozilla.org/show_bug.cgi?id=1536678) for a bit more debugging info. Also, I'm happy to provide whatever extra information as needed needed, or as I said at the beginning go complain somewhere else (Mesa, maybe?).
Thanks if you read until here :)