Mouse cursor stutters over GUI elements that are animated

[Daniel van Vugt]

[ Impact ]

Mouse cursor stutters over GUI elements that are animated, such as GTK apps, web pages and shell elements.

[ Test Plan ]

1. Open Settings.
2. Move the cursor up/down over an empty area of the desktop.
3. Move the cursor up/down over the list pane on the left side of the Settings window.

Expect: No difference in cursor smoothness whether the window below is animating in response to movement or not.

[ Where problems could occur ]

In frame scheduling, so the risk is more stuttering or screen freezes.

[ Workaround ]

Add this to /etc/environment:
CLUTTER_PAINT=disable-dynamic-max-render-time

[Daniel van Vugt (vanvugt)]

https://gitlab.gnome.org/Community/Ubuntu/mutter/-/commit/1987011f2d183a02160ae66afaf0e82218166521

[Daniel van Vugt (vanvugt)]

Fixed better in https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/3074

[Daniel van Vugt (vanvugt)]

There's a very similar fix in https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/3080 which applies to fullscreen direct scanout for bug 2016990. It looks like we should patch that at the same time as https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/3074.

[Daniel van Vugt (vanvugt)]

I wonder if https://gitlab.gnome.org/GNOME/mutter/-/issues/2334 can be the upstream for this?

[Daniel van Vugt (vanvugt)]

Debian fix proposed in https://salsa.debian.org/gnome-team/mutter/-/merge_requests/95

[Launchpad Janitor (janitor)]

This bug was fixed in the package mutter - 44.2-3ubuntu1

---------------
mutter (44.2-3ubuntu1) mantic; urgency=medium

  * Merge with Debian. Remaining changes:
    - Add x11-Add-support-for-fractional-scaling-using-Randr.patch
    - Add window-Add-ability-to-override-the-edge-constraints.patch
      + Make possible for extensions (such as Tiling Assistant) to override
        window constraints

mutter (44.2-3) experimental; urgency=medium

  * Cherry-pick patch to fix build test with mesa 23.1 (LP: #2025287)

mutter (44.2-2ubuntu1) mantic; urgency=medium

  * Merge with Debian. Remaining changes:
    - Add x11-Add-support-for-fractional-scaling-using-Randr.patch
    - Add window-Add-ability-to-override-the-edge-constraints.patch
      + Make possible for extensions (such as Tiling Assistant) to override
        window constraints

mutter (44.2-2) experimental; urgency=medium

  [ Daniel van Vugt ]
  * Cherry-pick 2 patches for stuttering fixes
    * Avoid cursor stuttering over some windows (LP: #2023766). This will also
      improve best-case input latency by roughly half a frame.
    * Avoid render stuttering in some fullscreen games (LP: #2016990).
  * Update Support-Dynamic-triple-double-buffering.patch
    * Fix a failure to resume from sleep (frozen black screen), which seems
      to be an old bug but only became likely in 44.1.
    * Fix a crash on resume from sleep (LP: #2020049).

 -- Jeremy Bícha <email address hidden> Wed, 28 Jun 2023 15:31:07 -0400

[Daniel van Vugt (vanvugt)]

Jammy fix proposed: https://salsa.debian.org/gnome-team/mutter/-/merge_requests/99

[Robie Basak (racb)]

Accepting into Jammy. I can see that the code changes appear already present in lunar-proposed. Please could you confirm the status of the fix in lunar-updates please, so we can avoid introducing a regression when users upgrade?

On test plans, I see both this bug and the other one will be individually tested, but what's the plan to ensure that other behaviour in mutter isn't regressed? https://wiki.ubuntu.com/DesktopTeam/TestPlans/Mutter exists, so would following that be appropriate, or do you want to do something else to verify this?

[Robie Basak (racb)]

Hello Daniel, or anyone else affected,

Accepted mutter into jammy-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/mutter/42.9-0ubuntu2 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-jammy to verification-done-jammy. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-jammy. 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)]

> On test plans, I see both this bug and the other one will be individually tested,
> but what's the plan to ensure that other behaviour in mutter isn't regressed?

Mutter and GNOME Shell are massive projects so the next bug is always somewhere you don't expect. I would not recommend focussing permanent test plans on any regressions that were found in 2023. Specifically addressing each one:

Bug 2026887: Caused by a narrow hardware/kernel combination. No more important than any other CPU model or kernel release.

Bug 2023759: Caused by a lack of testing remote desktop (upstream too). This could obviously be better tested but I argue the feature is too obscure to be a top-level test case we ask anyone to do on every update.

Bug 2023363: Caused by 16 milliseconds being too small a difference for most to notice.

Bug 2023766: Microstutters of a few milliseconds were a regression in 41.0 and went mostly unnoticed by everyone for several years because of how minor it is.

Bug 2017097: Caused by a combination of being too hard to notice for people who did test Raspi, and me being only one person too busy dealing with a rewrite of triple buffering caused by a last-minute upstream API redesign in 44.0.

Bug 2017137: Caused by a combination of being too hard to notice for people who did test Xorg, and me being only one person too busy dealing with a rewrite of triple buffering caused by a last-minute upstream API redesign in 44.0.

To find future regressions more effectively we need both more people testing proposed for longer, and more hardware/software combinations. Perhaps slower phasing too since such obscure bugs are so easy to miss by most people.

This isn't just a mutter issue. Almost every day I track obscure bugs back to the kernel caused by hardware combinations we simply can't expect to get tested exhaustively before every release.

[Daniel van Vugt (vanvugt)]

Verified fixed on jammy in 42.9-0ubuntu2. Tested using the test plan at the top of the page and also a 1000Hz Microsoft Classic IntelliMouse. I actually don't think the bug was as visible in 42.x as it was in 44.x. The reason is likely because triple buffering in 42.x didn't rely on the problematic dynamic-max-render-time feature as much as newer releases do. Still, the fix was missing before and seems to be performing well in 42.9-0ubuntu2.

[XA Hydra (xa-hydra)]

Fixed for me too. Also fixes drag and drop issues in many apps in where I would have to make multiple attempts before it would randomly succeed.

[XA Hydra (xa-hydra)]

Package version tested was 42.9-0ubuntu2 (replacing 42.9-0ubuntu1). Tested in a session running many active applications (Firefox, multiple windows with video, totem, Various chat applications, etc.)

[Andreas Hasenack (ahasenack)]

Hello Daniel, or anyone else affected,

Accepted mutter into jammy-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/mutter/42.9-0ubuntu3 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-jammy to verification-done-jammy. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-jammy. 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 jammy in 42.9-0ubuntu3. Tested using the test plan at the top of the page and a 1000Hz Microsoft Classic IntelliMouse.

[Steve Langasek (vorlon)]

Hello Daniel, or anyone else affected,

Accepted mutter into jammy-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/mutter/42.9-0ubuntu4 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-jammy to verification-done-jammy. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-jammy. 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 jammy in 42.9-0ubuntu4. Tested using the test plan at the top of the page and a 1000Hz mouse.

[Łukasz Zemczak (sil2100)]

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.

[Launchpad Janitor (janitor)]

This bug was fixed in the package mutter - 42.9-0ubuntu4

---------------
mutter (42.9-0ubuntu4) jammy; urgency=medium

  * Add Revert-data-udev-Don-t-disable-KMS-modifiers-on-newer-i91.patch
    to fix rendering failures on older kernels (5.15) when run on newer
    hardware (Intel Alder Lake). (LP: #2026887)

mutter (42.9-0ubuntu2) jammy; urgency=medium

  * Add clutter-frame-clock-Avoid-rapidly-toggling-dynamic-max-re.patch to
    avoid cursor stutter (LP: #2023766)
  * Add backends-x11-Return-zero-Hz-instead-of-nan-Hz-for-incompl.patch
    so that incomplete graphics mode definitions are reported as having a
    refresh rate of 0 Hz instead of -nan Hz. This also fixes the behaviour
    of the 'Revert Settings' button (LP: #2020782)

 -- Daniel van Vugt <email address hidden> Thu, 13 Jul 2023 08:15:36 -0400