Hello, I’m having trouble going from Qt 5.1 to 5.3 / 5.4 because of a slowdown in QML (15..35% slower). This primarily relates to component instantiation and seems quite consistent across the platforms and QPAs I’ve used recently.
If you have any insights, thoughts or something I could check I would highly appreciate them. I’ve tested on dual & quadcore imx6 (both EGLFS and XCB) embedded platform as well as few desktop Fedoras. I’ve tested with 5.1.1, 5.3.1 and the latest 5.4.0. The slowdown varies but is fairly consistently between 15..35 %. Instantiation CPU loads do not seem to be particularly high (< 70%). Running QML profiler seems to make results less predictable. So I made a very simple application startup timer that checks main() -> QQuickWindow::beforeSynchronizing() -> beforeRendering() -> afterRendering() -> frameSwapped(). Please find my "highly scientific" measurements below. I slowed down the CPU to make things more clear on the desktop I’m writing this email from. This behaviour is not specific to only application startup but later runtime instantiations seem also slower. I am grateful for any thoughts or things I could check. Thanks, Juha Qt 5.1.1 low CPU qtquickcontrols gallery example startup: 1. onBeforeSynchronizing() for the FIRST time, time it took from main(): 950 2. onBeforeRendering() time it took from beforeSynchronizing: 3 3. onAfterRendering() time it took from beforeRendering: 1572 4. onFrameSwapped() time it took from afterRendering: 5 = 2530 ms for first frame swapped. Qt 5.3.1 low CPU qtquickcontrols gallery example startup: 1. onBeforeSynchronizing() for the FIRST time, time it took from main(): 1843 2. onBeforeRendering() time it took from beforeSynchronizing: 364 3. onAfterRendering() time it took from beforeRendering: 1039 4. onFrameSwapped() time it took from afterRendering: 83 = 3329 ms for first frame swapped. Qt 5.1.1 low CPU my application startup: 1. onBeforeSynchronizing() for the FIRST time, time it took from main(): 809 2. onBeforeRendering() time it took from beforeSynchronizing: 3 3. onAfterRendering() time it took from beforeRendering: 1373 4. onFrameSwapped() time it took from afterRendering: 88 = 2273 ms for the first frame swapped Qt 5.3.1 low CPU my application startup: 1. onBeforeSynchronizing() for the FIRST time, time it took from main(): 1341 2. onBeforeRendering() time it took from beforeSynchronizing: 4 3. onAfterRendering() time it took from beforeRendering: 2184 4. onFrameSwapped() time it took from afterRendering: 10 = 3539 ms for the first frame swapped _______________________________________________ Interest mailing list Interest@qt-project.org http://lists.qt-project.org/mailman/listinfo/interest
