timerEvent response overtime

wang1209

I override a timerEvent and set its interval to 10 ms. Then I build the same code both in Windows 10 and Ubuntu 22.04. During run time, the Win version sometimes responsed between two timer slices over 50 ms, even 1 or 2 seconds. But the Ubuntu version run normly. Does it need more configuration in Windows' enviroment?

Christian Ehrlicher

@wang1209 said in timerEvent response overtime:

Does it need more configuration in Windows' enviroment?

No, nothing you can do except you switch to a real-time OS.

JonB

@wang1209
I don't use Windows but did you read through enum Qt::TimerType and try Qt::PreciseTimer? Or there is QChronoTimer, though I think that is overkill for 10ms.

wang1209

@JonB Yes, I set the second parameter as Qt::PreciseTimer when I call startTimer() like

timerID=startTimer(10, Qt::PreciseTimer);

JonB

@wang1209
Well all I know is that the link says

On Windows, Qt will use Windows's Multimedia timer facility (if available) for Qt::PreciseTimer and normal Windows timers for Qt::CoarseTimer and Qt::VeryCoarseTimer.

Maybe Multimedia timer is not available to you or it's still not accurate, I don't know. For the sake of completeness did you check QChronoTimer? You could also test Windows native WM_TIMER or other to see if it's any more accurate than from Qt. If you can't find anything more accurate in Windows then as @Christian-Ehrlicher says maybe you'll never get it out of non-real-time Windows.

Pl45m4

@wang1209

https://learn.microsoft.com/en-us/windows-hardware/drivers/kernel/high-resolution-timers#controlling-timer-accuracy

You can't rely on Windows timer precision in exact milliseconds.
Don't know how Qt's "precise" timer is implemented and what it does to the OS (i.e. Windows)...
as @JonB and @Christian-Ehrlicher say above, for very time sensitive tasks, an RTOS such as QNX or ROS is more suited... but all depends on your use case.