[uae] Re: New binaries for testing

  • From: Richard Drummond <evilrich@xxxxxxxxxxxxxx>
  • To: uae@xxxxxxxxxxxxx
  • Date: Sun, 8 May 2005 23:07:29 -0500

On Wednesday 20 April 2005 08:57 am, Richard Drummond wrote:
> Having said that, without the JIT engine, the overhead of the timer call is
> less of a factor on the speed of the emulation.

Talking out of my arse, there. ;-)

The overhead of the timer call makes a huge difference to the interpretive 
emulator when m68k_speed=max. When in 'max' mode, after the number of machine 
cycles alotted for a frame is complete, the interpreter keeps on executing 
opcodes until the next frame is due. It does this by polling the time after 
each opcode. So - in 'real' or 'adjustable' CPU modes, the timer overhead 
isn't a big deal; in 'max' mode it can be crippling. You can end up with a 
'max' mode that isn't much faster than the 'real' mode. :-(

When the JIT is built-in however, a slightly different method is used in the 
interpeter in 'real' mode. It doesn't poll the time so often, so the overhead 
of the timer call is less.

Anyway, I have some ideas how to fix this.


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