On quarta-feira, 26 de julho de 2017 12:58:43 PDT Joshua Grauman wrote: > Hello all, > > I have a QTimer in my application that runs every 40ms. It doesn't run > continuously, but I recall the start function every time my timer function > is done so that the timer doesn't drift over time. My question though is > about timeout overrun. If the system is busy, and so the timer is late, > will Qt::PreciseTimer be more likely to return on time than > Qt::CoarseTimer? In other words, I'm ok with the 5% accuracy of > Qt::CoarseTimer normally (when the system isn't busy), but when the 40ms > timer is getting close to 60ms, I want to avoid timer overrun.
The type of timer is not relevant. All timers behave the same way: if it's serviced as soon as it's available and the next wake up will always be the current time + interval (± coarseness, if applicable). Qt does not control when the OS gives us CPU time to service the timers. If you need that, you need to consult your OS API and create a high-priority thread or process, something that usually requires privilege elevation. Qt cannot help you there. > Does anyone have any more precise info about Qt::PreciseTimer than the > docs which say: > > "All timer types may time out later than expected if the system is busy > or unable to provide the requested accuracy. In such a case of timeout > overrun, Qt will emit activated() only once, even if multiple timeouts > have expired, and then will resume the original interval." There is no more info to be had. -- Thiago Macieira - thiago.macieira (AT) intel.com Software Architect - Intel Open Source Technology Center _______________________________________________ Interest mailing list Interest@qt-project.org http://lists.qt-project.org/mailman/listinfo/interest
