Hi everyone, below you will find the updates from the Desktop team from the last week.
If you’re interested in discussing a topic please start a thread in the Desktop area of the Community Hub (this site).
We also have our weekly meeting on IRC. We meet on Tuesday at 13:30 UTC in #ubuntu-desktop on Freenode. There will be an “Any Other Business” section at the end where you are welcome to raise topics. These topics might be discussed during the meeting, or afterwards depending on the time, depth of conversation, topic and so on.
Last week’s notes are here: Monday 18th March 2019
Next week’s notes are here: https://community.ubuntu.com/t/monday-1st-april-2019/10436
Gnome Shell performance (stutter | latency | CPU):
Investigations related to fractional scaling:
- Spent a day investigating panel menu rendering problems which only seem to occur with fractional scaling +
ClutterOffscreenEffect. This is somewhat my responsibility since I touched
ClutterOffscreenEffect last and seem to know that area best.
- Stopped due to a higher Ubuntu priority below…
- Most of the week investigating tearing in the proposed X11 fractional scaling support:
- Found it is caused by using Xrandr because no compositor can (yet) flip an image to the kernel that’s a different resolution from the monitor.
- Relearned how to build and debug Xorg.
- Found that the present extension is already asking the modesetting driver to sync to vblank. Just that the modesetting driver’s preferred vsync method is inaccurate in Xrandr scaled configurations. It’s the right vsync frequency but out of phase after the time glamor takes to render to the scaled-down buffer using single buffering. Hence tearing. So the root cause of the problem is that it’s using single buffered scanouts when scaling. It should be double buffered.
- Also found that the i915 kernel driver doesn’t yet adequately support the KMS DRM “scaling mode” property, which would allow us to move scaling into the kernel and avoid having to do it manually with GL and would avoid tearing.
- Started some early attempts at a fix, although it was also pointed out a related big fix is coming upstream.
Gnome Shell other bugs:
Release bugs (little progress this week due to the above disco issues):
Good news (falling backlogs): gnome-control-center, nautilus, firefox, thunderbird
Bad news (consistently growing backlogs): ubiquity
Shorter week (1 day off):
- tests for dataset naming and container/contained datasets naming swaps.
- looked at initramfs-zfs scritps to find main datasets, snapshot built-in functionality and such.
Sorry, I’ve had some other things come up and didn’t prepare an update this week.