[Development] QSystemAlignedTimer to QtCore

[Thiago Macieira]

On Tuesday, 22 de November de 2011 10.05.49, lars.knoll at nokia.com wrote:
> Agree, but it shouldn't be difficult to do a generic backend based on the
> system clock. So if you want to wakeup every 5 minutes, we'll always do
> that at a defined clock time for all apps. We could simply say when the
> system clock shows a round multiple of 5 minutes.
> 
> The generic fallback might not be ideal, as all apps wake up at exactly
> the same time and not one after the other, but would IMO be good enough
> for most use cases.

The kernel scheduler should take care of queuing the applications that request 
activation. I know that at least on Linux, the kernel will already round 
timers up to a certain threshold (50 ns by default) and it can be changed by 
prctl(2) with PR_SET_TIMERSLACK.

We'll be asking for almost exactly the same wake-up time from all processes, 
modulo timing errors that should be below the threshold or below the 
capability of the system to run all such processes. In practice, the processes 
will be queued up and woken up in sequence.

I'd prefer to have the system-aligned timer to be just another mode in the 
coarseness grade that I created, renaming the ones I added. I wonder how 
useful it would be to have the wakeup window in all modes...

-- 
Thiago Macieira - thiago.macieira (AT) intel.com
  Software Architect - Intel Open Source Technology Center
     Intel Sweden AB - Registration Number: 556189-6027
     Knarrarnäsgatan 15, 164 40 Kista, Stockholm, Sweden
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