** Description changed:

  [ Impact ]
  
  On the affected Ubuntu 24.04 system, fullscreen applications can run at
  approximately 37-55 FPS on a 75 Hz display, causing visible stutter.
  
  Mutter: 46.2-1ubuntu0.24.04.16
  
- 
  [ Test Plan ]
  
- 1. On an affected Ubuntu 24.04 GNOME Wayland system, configure the display to
-    1920x1080 at approximately the panel refresh rate.
+ 1. Log into a Wayland session.
  
  2. Restart GDM or log out and back in. Confirm that a new GNOME Shell process
-    is running.
+    is running.
  
  3. Run for at least 120 seconds and record every five-second FPS report:
  
-    glxgears -fullscreen
+    glxgears -fullscreen
  
- 4. Repeat from a new graphical session. Expect sustained periods where the 
framerate
-    is approximately the same as the monitor refresh rate.
- 
+ 4. Verify FPS stays near the display refresh rate and stutter/vblank
+ misses no longer occur.
  
  [ Where problems could occur ]
  
- TBD
+ The change does not alter the actual KMS update contents, modesetting
+ logic, buffer selection, or page-flip handling. It only adjusts the
+ timing margin used to decide when to submit updates. If problems occur,
+ they are most likely to be performance/timing issues such as latency or
+ frame pacing changes, not crashes or display configuration failures.
  
  [ Other Info ]
+ 
+ MR: https://salsa.debian.org/gnome-team/mutter/-/merge_requests/180
+ 
+ This is a Noble-specific workaround for Mutter 46. It is not forwarded
+ upstream because newer Mutter versions handle this differently with KMS-ready
+ timestamp tracking introduced by upstream Mutter MR !4825.

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https://bugs.launchpad.net/bugs/2167418

Title:
  [Draft][SRU] mutter: fullscreen applications run below the display
  refresh rate

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