[uae] Re: New binaries for testing

  • From: Richard Drummond <evilrich@xxxxxxxxxxxxxx>
  • To: uae@xxxxxxxxxxxxx
  • Date: Wed, 20 Apr 2005 08:57:25 -0500

Hi Henk

On Wednesday 20 April 2005 05:37 am, Henk Jonas wrote:
> what do you think, how much will the timing affect the emulation speed.
> My Palm OS port uses the internal tick as timer. The tick rate is 100
> per second. Can you make a quick assumption if a more accurate timer
> would either speed up the emulation or could increase sound quality? Or
> is 100 per second quite sufficient.

The timer is used for frame timing - i.e. to calculate when and - if the 
emulation is in real mode - wait until the next frame is due.

The timer thus needs at least to be 50 Hz. A 100 Hz timer should be okay, 
although it's probably pushing the line. A 1 kHz timer would definitely be 
preferable. My intuition tells me that using a 100 Hz timer shouldn't impact 
overall throughput of frames, although it may affect the smoothness of the 
emulation when cpu_speed=real. (The method used to sleep in real mode when 
waiting for the next frame will also be a factor. Since your timer has 10 ms 
granularity, I wouldn't recommend using that for busy-waiting).

The question whether you'd be better using a higher resolution timer is a 
difficult one. It's probably best to try it out. If using the finer-grained 
timer has a much greater overhead, then it may be better to stick with the 
100 Hz timer.

Having said that, without the JIT engine, the overhead of the timer call is 
less of a factor on the speed of the emulation.


Other related posts: