So it seems like the issue is a combination of: 1. Unity8 using a zero swap interval (somehow, by accident?) 2. Unity8 taking around 10ms to render each frame -> 100Hz 3. USC can only take one frame every 16.6ms (60Hz), so will drop half of what Unity8 produces.
This yields only 50Hz output to the screen, which is roughly only every second frame from Unity8 reaching the screen, on an interval that's out of phase with the screen. So that's the stuttering. ** Changed in: mir Milestone: 0.26.1 => 1.0.0 ** Changed in: mir Status: New => In Progress ** Also affects: mir/0.26 Importance: Undecided Status: New ** Changed in: mir/0.26 Importance: Undecided => High ** Changed in: mir/0.26 Status: New => Confirmed ** Changed in: canonical-devices-system-image Status: New => Confirmed ** Changed in: mir/0.26 Milestone: None => 0.26.1 ** Changed in: mir/0.26 Assignee: (unassigned) => Daniel van Vugt (vanvugt) ** Description changed: - Unity8 stutters constantly (like half frame rate) on an i7 desktop. + Unity8 stutters constantly (like half frame rate) on a high-end desktop. This regression only happened recently, perhaps due to the introduction of Mir 0.26.0. Surprisingly though, using the same Mir release I can start a demo server on another VT and everything is silky-smooth. The problem only seems to occur with Unity8. -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to unity8 in Ubuntu. https://bugs.launchpad.net/bugs/1661128 Title: [regression] Unity8 stutters constantly (like half frame rate) Status in Canonical System Image: Confirmed Status in Mir: In Progress Status in Mir 0.26 series: Confirmed Status in unity8 package in Ubuntu: Confirmed Bug description: Unity8 stutters constantly (like half frame rate) on a high-end desktop. This regression only happened recently, perhaps due to the introduction of Mir 0.26.0. Surprisingly though, using the same Mir release I can start a demo server on another VT and everything is silky-smooth. The problem only seems to occur with Unity8. To manage notifications about this bug go to: https://bugs.launchpad.net/canonical-devices-system-image/+bug/1661128/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp