Very poor multi-monitor performance in Wayland sessions

[Luis Alberto Pabón]

Upstream bug:
https://gitlab.gnome.org/GNOME/mutter/issues/3

---

When dragging a window between displays, I can see cpu usage increase while framerate drops dramatically to single numbers.

Desktop scaling is 1.0, one is a WXGA screen and another FHD.

Ubuntu session (wayland), 17.10.

ProblemType: Bug
DistroRelease: Ubuntu 17.10
Package: gnome-shell 3.26.1-0ubuntu5
ProcVersionSignature: Ubuntu 4.13.0-16.19-lowlatency 4.13.4
Uname: Linux 4.13.0-16-lowlatency x86_64
ApportVersion: 2.20.7-0ubuntu3.1
Architecture: amd64
CurrentDesktop: Unity:Unity7:ubuntu
Date: Mon Nov 6 17:09:20 2017
DisplayManager: lightdm
GsettingsChanges:
 b'org.gnome.shell' b'favorite-apps' b"['/home/development/bin/firefox.desktop', 'org.gnome.Nautilus.desktop', 'jetbrains-phpstorm.desktop', 'code.desktop', 'postman.desktop', 'standard_notes.desktop']"
 b'org.gnome.desktop.interface' b'gtk-im-module' b"'gtk-im-context-simple'"
 b'org.gnome.desktop.interface' b'icon-theme' b"'ePapirus'"
 b'org.gnome.desktop.interface' b'gtk-theme' b"'DarkNumix'"
InstallationDate: Installed on 2016-03-13 (603 days ago)
InstallationMedia: Ubuntu 16.04 LTS "Xenial Xerus" - Alpha amd64 (20160307)
SourcePackage: gnome-shell
UpgradeStatus: Upgraded to artful on 2017-10-19 (17 days ago)

[Sebastien Bacher (seb128)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. The issue you are reporting is an upstream one and it would be nice if somebody having it could send the bug to the developers of the software by following the instructions at https://wiki.ubuntu.com/Bugs/Upstream/GNOME. If you have done so, please tell us the number of the upstream bug (or the link), so we can add a bugwatch that will inform us about its status. Thanks in advance.

[Daniel van Vugt (vanvugt)]

Luis, you say "Ubuntu session (wayland)" but the bug report says "CurrentDesktop: Unity:Unity7:ubuntu"

Please confirm if the bug was happening in gnome-shell or unity.

[Luis Alberto Pabón (copong)]

This was happening on gnome-shell, not unity. The report says unity I gather because the crashes got so bad I had to switch back.

I feel it might be tied up to the dynamic transparency stuff on either the top panel, or the dock. I opened another bug about the crashes here: https://bugs.launchpad.net/ubuntu/+source/gnome-shell/+bug/1735127

[Daniel van Vugt (vanvugt)]

Luis,

My continuing experience with framerate drops and high CPU is that they usually turn out to be two different bugs. If the CPU spike occurs when you drag a window under the dock then that might be bug 1743976, which occurs when things change under or very near the dock.

Ideally let's keep this bug about just the framerate drop.

[Daniel van Vugt (vanvugt)]

Luis,

Also does the problem go away with "Ubuntu on Xorg"?

If so then we should link to: https://gitlab.gnome.org/GNOME/mutter/issues/3

[Luis Alberto Pabón (copong)]

Roger that Daniel. I can confirm it doesn't happen on X.

[Daniel van Vugt (vanvugt)]

Alright then, let's consider https://gitlab.gnome.org/GNOME/mutter/issues/3 as the upstream bug here. Unfortunately we can't link to gitlab bugs properly from Launchpad yet.

[dreamcat4 (dreamcat4)]

multiple monitors on xorg
=============================

Was recently discussed over on https://bugs.launchpad.net/ubuntu/+source/mutter/+bug/1763892

Another user + myself have the following issue:

The slowest connected display limits the FPS. The test case we used is over at the top of the other bug report ^^

This we found today happens with either amd vega graphics, or nvidia pascal graphics, the vendor doesn't seem to matter. We have both seen the same issue (xorg).

This is on 18.10, and booting into the 'Gnome (xorg)' login option. With the FPS being logged by journalctl -f. With only single monitor attached. Then it initially goes as high as the primary monitor can show. (And glmark2 running in background, to maintain a continued load). Which is 120fps for my case. Then as soon as secondary monitor is plugged in, which is a 60hz TV. This is being plugged into the HDMI port of the same graphics card in real time. Then the FPS logged by 'journalctl -f' drops, and becomes capped to 60hz, in the output being printed by journalctl -f.

My setup:
kernel 5.0.0-050000-lowlatency #201903032031
NVIDIA Driver for UNIX platforms 415.27 (the closed source one)
ubuntu 18.10

mutter version:

mutter/cosmic-updates,now 3.30.2-1~ubuntu18.10.4 amd64 [installed]
mutter-common/cosmic-updates,cosmic-updates,now 3.30.2-1~ubuntu18.10.4 all [installed]

To confirm where the '.4' at the very end of the ~ubuntu18.10.4 version number, it seems to be that we have updated now on our client machines the be most recent bugfix updates, kindly provided by Daniel. Which closed the other bug https://bugs.launchpad.net/ubuntu/+source/mutter/+bug/1763892 being referred to, as being solved for people's single monitor scenarios.

Thanks again for the other recent bug fixes in this area, it is a nice progress. Very helpful! We hope you can also look into this latest problem / issue for the multiple monitor scenario.

[Daniel van Vugt (vanvugt)]

dreamcat4,

This bug is specifically about Wayland sessions. I now realize if you see similar problems in Xorg then that's a problem with the Xorg graphics drivers so please open a new bug for Xorg.

[dreamcat4 (dreamcat4)]

multi-monitor FPS bug for xorg, discussion moved to ---> https://bugs.launchpad.net/ubuntu/+source/gnome-shell/+bug/1820832

[Daniel van Vugt (vanvugt)]

I would usually recommend keeping /unused/ gnome-shell tasks so that other users can find the bug more easily. Then remove the task at the end.

[Luis Alberto Pabón (copong)]

:O

[Launchpad Janitor (janitor)]

This bug was fixed in the package mutter - 3.37.91-1ubuntu1

---------------
mutter (3.37.91-1ubuntu1) groovy; urgency=medium

  * Merge with debian, including new upstream stable release, remaining changes:
    - debian/gbp.conf: update upstream branch to point to ubuntu/master
    - debian/patches/x11-Add-support-for-fractional-scaling-using-Randr.patch:
      + X11: Add support for fractional scaling using Randr
  * d/p/x11-Add-support-for-fractional-scaling-using-Randr.patch:
    - Refresh as per upstream changes

mutter (3.37.91-1) experimental; urgency=medium

  * New upstream release
    - Support unredirecting fullscreen wayland surfaces
    - Support area screencasts
    - Allow inhibiting remote access
    - Drive each monitor by its own frame clock (LP: #1730460)
    - Fix copy/paste failures on X11 (LP: #1879968)
    - Make window-aliveness checks less aggressive
    - Limit mipmap levels when rendering background (LP: #1862308)
    - Remove more long-deprecated Clutter APIs
    - Support custom keyboard layouts in $XDG_CONFIG_HOME/xkb
    - Optimize resource scale computation for wayland fractional scaling
    - Support tap-button-map and tap-drag-lock touchpad settings
    - Fix wine copy & paste
    - Add API to launch trusted wayland clients
    - Invalidate offscreen effect cache on video memory purge (LP: #1855757)
  * debian: Update package and file names to mutter API version
  * debian/control: Bump dependencies to match upstream requirements
  * debian/clean: Remove as HOME and XRD are managed now by dh
  * debian/copyright: Avoid redundant globbing patterns
  * debian/gbp.conf: target upstream/latest branch
  * debian/libmutter-7-0.symbols: Update symbols file
  * debian/patches: Refresh
  * d/p/debian/tests-Tag-closed-transient-no-input-tests-as-flaky.patch:
    - Renamed into d/p/debian/tests-Tag-unstable-tests-as-flaky.patch
    - Reduced the number of "flaky" tests to the ones time-dependent only
  * debian/rules:
    - Compute and generate a MUTTER_API_VERSION and replace it everywhere
    - Remove XDG_RUNTIME_DIR wrapper workaround
    - Don't run tests at all in riscv64
    - Don't set again default configuration values (it makes the delta clearer)
    - Never ignore test failures in amd64
    - Remove test num processes re-configuration
    - Run tests in s390x, no failures currently
    - Don't test in alpha hppa powerpc sparc64 x32 (Closes: #959415)
  * debian/with-temp-xdg-runtime-dir: Dropped, new dh will handle it for us
  * debian/watch: Scan for all versions, not just the stable-branch
  * debian/*.install: Use dh variable substitution in install files

mutter (3.36.5-1) unstable; urgency=medium

  * Team upload
  * New upstream release
    - Screencast fixes and improvements
    - Fix glitches when subsurfaces extend outside the toplevel
    - Improve background display in overview workspace switcher
    - Fix wine copy & paste
    - Plug memory leaks
  * Drop patches that were applied upstream

 -- Marco Trevisan (Treviño) <email address hidden> Fri, 28 Aug 2020 01:10:32 +0200