GNOME 44.0 Xorg sessions on Intel GPUs stutter noticeably in 23.04

[Daniel van Vugt]

[ Impact ]

Xorg sessions on Intel GPUs stutter noticeably in 23.04

Seems like a combination of:

 * over-aggressive latency optimizations in the latest version of triple buffering; and
 * gnome-shell 44 being slightly less efficient at some operations like scrolling the app grid.

[ Workaround ]

Add this to /etc/environment:

  MUTTER_DEBUG_TRIPLE_BUFFERING=always

[ Test Plan ]

1. Find a machine with an Intel GPU.

2. Log into 'Ubuntu on Xorg'.

3. Press Super+A and scroll the icon right left/right. It should be perfectly smooth like in Wayland sessions.

[ Where problems could occur ]

Triple buffering affects all frame scheduling so any mistakes can cause high CPU usage, screen freezes and stutter. Try not to make mistakes.

[Daniel van Vugt (vanvugt)]

Probably related to bug 2017097

[Daniel van Vugt (vanvugt)]

Fix committed to https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1441 but I am waiting till there is a 44.1 tag before rebasing, branching, and proposing a new triple buffering patch to salsa. I will also be away till Monday so it probably won't happen before then.

[Daniel van Vugt (vanvugt)]

Fixed in mutter 44.1 which is now in Ubuntu 23.10

[Chris Halse Rogers (raof)]

Hello Daniel, or anyone else affected,

Accepted mutter into lunar-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/mutter/44.1-0ubuntu1 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, what testing has been performed on the package and change the tag from verification-needed-lunar to verification-done-lunar. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-lunar. In either case, without details of your testing we will not be able to proceed.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance for helping!

N.B. The updated package will be released to -updates after the bug(s) fixed by this package have been verified and the package has been in -proposed for a minimum of 7 days.

[Daniel van Vugt (vanvugt)]

Verified fixed on lunar in mutter 44.1-0ubuntu1

[Launchpad Janitor (janitor)]

This bug was fixed in the package mutter - 44.1-0ubuntu1

---------------
mutter (44.1-0ubuntu1) lunar; urgency=medium

  [ Jeremy Bícha ]
  * New upstream release (LP: #2020225, LP: #2012717, LP: #2013216,
    LP: #2015861, LP: #2017097)
  * debian/libmutter-12-0.symbols: Add new symbols
  * Drop 3 patches applied in new release

  [ Daniel van Vugt ]
  * Update triple buffering patch for Mutter 44.1 (LP: #2017137)

 -- Jeremy Bícha <email address hidden> Fri, 19 May 2023 16:18:13 -0400

[Robie Basak (racb)]

The verification of the Stable Release Update for mutter has completed successfully and the package is now being released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regressions.