Re: [AD] Add timeBeginPeriod(1) to wtimer.c

["Tobias Scheuer" <tobing@xxxxxxxxxx>]

I think you're right. But my measurements have given different results,
though I can't explain all the details. It might also depend on the machine
and graphics adapter. Did you try the change on Windows on your PC? 


> allegro uses timeGetTime() in its low_perf_thread  which would be 
> effected, but in my opinion, a good way.
> it uses a WaitForSingleObject() which will signal when the time is right 
>   regardless of how much resoltuion was used to set the time.
> i dont see how it can be effecting anything, if anything, it should be 
> making everything more responsive.
> 
> aj.
> 
> 
> 
> Tobias Scheuer wrote:
> > I think it affects the timers more generally, so it also affects the
> timers
> > in allegro's separate timer threads. Didn't go into all the details, and
> I
> > don't have a decent profiler at home, so I couldn't find out where
> exactly
> > the slowdown comes from. Maybe I should try to Quantify this at work... 
> > 
> > 
> >>it changes the resolution of the rest() and timeGetTime()  but it 
> >>doesn't slow down the app itself.
> >>how could it ?
> >>
> >>
> >>
> >>Tobias Scheuer wrote:
> >>
> >>>I have tried that. The documentation says that each call to
> >>
> >>timeBeginPeriod
> >>
> >>>has to be matched by a call to timeEndPeriod, so that#s why I have also
> >>>called that function. If I leave that out, the timeBeginPeriod(1)
> >>
> >>remains
> >>
> >>>active, which causes some overall slowdown of the whole program (as
> >>>mentioned in the forum). 
> >>>
> >>>
> >>>
> >>>>timeBeginPeriod only needs to be called once for the whole process.
> >>>>not each time rest is called.
> >>>>
> >>>>
> >>>>
> >>>>
> >>>>
> >>>>>Hi all,
> >>>>>
> >>>>>as already discussed in the forum, I would propose to change the
> >>
> >>current
> >>
> >>>>>implementation of tim_win32_rest in wtimer.c to the following:
> >>>>>
> >>>>>[code]
> >>>>>/* tim_win32_rest:
> >>>>>*  Rests the specified amount of milliseconds.
> >>>>>*/
> >>>>>static void tim_win32_rest(unsigned int time, AL_METHOD(void,
> callback,
> >>>>>(void)))
> >>>>>{
> >>>>>  unsigned int start;
> >>>>>  unsigned int ms = time;
> >>>>>
> >>>>>  const MMRESULT rc = timeBeginPeriod(1);
> >>>>>  if (callback) {
> >>>>>     start = timeGetTime();
> >>>>>     while (timeGetTime() - start < ms)
> >>>>>        (*callback)();
> >>>>>  }
> >>>>>  else {
> >>>>>     Sleep(ms);
> >>>>>  }
> >>>>>  if( rc == TIMERR_NOERROR )
> >>>>>    timeEndPeriod(1);
> >>>>>}
> >>>>>[/code]
> >>>>>
> >>>>>The new lines are the call to timeBeginPeriod(1); and the 
> >>>>>correcponding call
> >>>>>to timeEndPeriod(1); in case the first call was successful.
> >>>>>
> >>>>>This affects only windows, and increases the accuracy of calls to 
> >>>>>rest(n).
> >>>>>
> >>>>>For the discussions, refer to the following threads:
> >>>>>
> >>>>>http://www.allegro.cc/forums/view_thread.php?_id=456146
> >>>>>http://www.allegro.cc/forums/view_thread.php?_id=453116
> >>>>>
> >>>>>As this is my very first contribution, please forgive if anything is 
> >>>>>not in
> >>>>>the right format or otherwise unexpected.
> >>>>>
> >>>>>Thanks for consideration!
> >>>>>
> >>>>>Best regards Tobias
> >>>>>
> >>>>>-- 
> 
> 
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