https://bugs.kde.org/show_bug.cgi?id=419387
Bug ID: 419387 Summary: Frame drops when the second monitor has 30Hz refresh rate Product: kwin Version: 5.18.3 Platform: openSUSE RPMs OS: Linux Status: REPORTED Severity: normal Priority: NOR Component: general Assignee: kwin-bugs-n...@kde.org Reporter: i...@guoyunhe.me Target Milestone: --- SUMMARY When you have two monitors with different refresh rates, the one higher refresh rate drop frames (noticeably). STEPS TO REPRODUCE 1. Connect to two 1080p monitors, we call them A and B 2. In KDE Settings, set refresh rates of both to 60Hz 3. Watch this video in monitor A https://www.youtube.com/watch?v=Cyxixzi2dgQ 4. In KDE Settings, set refresh rate of A to 60Hz and B to 30Hz 5. Watch the same video in monitor A 6. Shift+Alt+F12 to disable KWin composition 7. Watch the same video in monitor A OBSERVED RESULT When B is 60Hz, monitor A doesn't drop frames. When B is 30Hz, monitor A drop frames noticeably. When B is 30Hz but KWin composition is off, monitor A doesn't drop frames. EXPECTED RESULT Monitor A shouldn't drop frames when monitor B has a different refresh rate. SOFTWARE/OS VERSIONS Operating System: openSUSE Tumbleweed 20200326 KDE Plasma Version: 5.18.3 KDE Frameworks Version: 5.68.0 Qt Version: 5.14.1 Kernel Version: 5.5.11-1-default OS Type: 64-bit Processors: 8 × Intel® Core™ i7-8550U CPU @ 1.80GHz Memory: 31.1 GiB ADDITIONAL INFORMATION I think this is not deal to GPU performance limitation, because when you reduce refresh rate of monitor B, the total computing load is smaller and GPU should render faster. -- You are receiving this mail because: You are watching all bug changes.