On 5 Sep 2014, at 09:39, Nancy Zou <[email protected]> wrote: > Hi Millan >> You should answer this question yourself and present the results to us. Only >> you have your specific software/hardware combination setup properly. > > I suspect Qt wati for vsyc somewhere because the normal opengl example only > cost 14ms (1 vsync) and Qt example openglwindow need 28 ms( just 2 vysnc) > I think it's strange a simple opengl example run such low fps. > My fb driver already wait for vsync once in eglSwapBuffers. So Qt don't need > wait it. So I want to find out where qt hung. Whether Qt wait for some events > somewhere?
Qt QPA plugins do the waiting precisely by calling eglSwapBuffers. You can control the swap interval by means of QSurfaceFormat::setSwapInterval(). Pass in a value of 0 to disable any sync, -1 to use adaptive sync (if your driver supports it), any other positive integer for that number of syncs. Also make sure the QPA has the correct refresh rate for your screen. Cheers, Sean > >> Try Linux' `perf top` e.g. or run your application via `perf record >> --call-graph=dwarf yourapp`. Then do a `perf report` and take a look at the >> results. Remember to compile your application and all important >> dependencies (esp. Qt) in release mode with debug symbols, i.e. at least use >> the compile flags `-O2 -g`. > > I have done this in qmake. > > > Thank you > > Best Regards > Nancy > > > Member of the CSR plc group of companies. CSR plc registered in England and > Wales, registered number 4187346, registered office Churchill House, > Cambridge Business Park, Cowley Road, Cambridge, CB4 0WZ, United Kingdom > More information can be found at www.csr.com. Keep up to date with CSR on our > technical blog, www.csr.com/blog, CSR people blog, www.csr.com/people, > YouTube, www.youtube.com/user/CSRplc, Facebook, > www.facebook.com/pages/CSR/191038434253534, or follow us on Twitter at > www.twitter.com/CSR_plc. > New for 2014, you can now access the wide range of products powered by aptX > at www.aptx.com. > _______________________________________________ > Development mailing list > [email protected] > http://lists.qt-project.org/mailman/listinfo/development Dr Sean Harmer | [email protected] | Managing Director UK Klarälvdalens Datakonsult AB, a KDAB Group company Tel. Sweden (HQ) +46-563-540090, USA +1-866-777-KDAB(5322) KDAB - Qt Experts - Platform-independent software solutions _______________________________________________ Development mailing list [email protected] http://lists.qt-project.org/mailman/listinfo/development
