"Match x Speed" timing with JIT

30 January 2004, 20:51

WinUAE is so fast, that it would be cool to have beside the "Match A500 Speed" also the possibility to choose from "Match A1200 Speed", "Match 68030/25 Speed", etc. Some AGA Games and AGA Demos are just running too fast with JIT activated.

I don´t know how much work this would take to implant this additional feature, but I would love it

Nyarlathotep · 30 January 2004, 22:07

I think it would be very difficult. (and slow)
68020 and better processors have internal cache, so their speed depends upon the presence of istructions and data in cache.
Matching the speed of a true 68020 requires the analisys, every cycle, of the cache.

Toni Wilen · 31 January 2004, 08:53

Correct, 68020's instruction cache is much faster than chip ram and the difference will be even bigger in high color/resolution modes..

I think cache emulation will be much more important than exact instruction execution speed.

31 January 2004, 20:31

Ok, no prob. I did´nt know that it would be so difficult to implent this for cpu´s with cache

30 January 2004, 20:51	#1
Ralph Wiggum Posts: n/a	"Match x Speed" timing with JIT WinUAE is so fast, that it would be cool to have beside the "Match A500 Speed" also the possibility to choose from "Match A1200 Speed", "Match 68030/25 Speed", etc. Some AGA Games and AGA Demos are just running too fast with JIT activated. I don´t know how much work this would take to implant this additional feature, but I would love it

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30 January 2004, 22:07	#2
Nyarlathotep Zone Friend Join Date: May 2002 Location: Italy Posts: 148	I think it would be very difficult. (and slow) 68020 and better processors have internal cache, so their speed depends upon the presence of istructions and data in cache. Matching the speed of a true 68020 requires the analisys, every cycle, of the cache.

31 January 2004, 08:53	#3
Toni Wilen WinUAE developer Join Date: Aug 2001 Location: Hämeenlinna/Finland Age: 49 Posts: 26,502	Correct, 68020's instruction cache is much faster than chip ram and the difference will be even bigger in high color/resolution modes.. I think cache emulation will be much more important than exact instruction execution speed.

31 January 2004, 20:31	#4
Ralph Wiggum Posts: n/a	Ok, no prob. I did´nt know that it would be so difficult to implent this for cpu´s with cache

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