Hi Tor, I have created a bug report (https://bugreports.qt.io/browse/QTBUG-100943) as you requested. Please note that my Qt patch only forces the QOffscreenSurface to be window-backed.
Regards, Sivan On Wed, Feb 16, 2022 at 6:58 PM Tor Arne Vestbø <[email protected]> wrote: > Thanks for the detailed report Sivan. Can you file an issue about in > https://bugreports.qt.io/ with the sample code, and a diff of the changes > you made to improve performance? Thanks! > > On 16 Feb 2022, at 11:53, sivan nanthiran <[email protected]> wrote: > > Hi, > > Recently I have upgraded from Qt-5.4.1 to Qt-5.15.2. The following is my > system configuration: > - MacOS > - External display connected to External GPU, and made as the primary > screen, connected to a macbook > > In my simple testApp, I have 2 QOpenGLWidget and 1 QWidget. I just simply > render a triangle in those QOpenGLWidgets which changes color every 16ms. > > The rendering performance in my app used to be 60fps as it was rendering > on the external GPU. However, after Qt-5.15 upgrade, I noticed the > performance is about 45fps and there are load in my macbook's Intel GPU. > > Upon investigating, I found out that its due to QOffscreenSurface's change > to be not window-backed anymore. Since QOpenGLWidget internally uses > QOffscreenSurface, I believe this is causing the rendering to not happen on > the screen's GPU. When I hack the code to make the QOffscreenSurface to > window-backed, I'm able to get the same performance as before. > > So is there any clean way to achieve the same performance I used to > achieve? If not, are there any effects if I force the QOffscreenSurface to > be window backed for MacOS? > > Thanks in advance. > > Regards, > Sivan > > > _______________________________________________ > Interest mailing list > [email protected] > https://lists.qt-project.org/listinfo/interest > > >
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