Re: [hatari-devel] WinUAE CPU core cycle-exact option impact for 68000

[Thorsten Otto <admin@xxxxxxxxxxx>]

On Freitag, 17. Januar 2020 18:41:01 CET Roger Burrows wrote:

 

Thanks for the hint, but turning that option on or off does not change anything. I still get 30 loops when cycle-exact is on.

 

> On 17 Jan 2020 at 11:53, Thorsten Otto wrote:

> > While trying to do some benchmarks for EmuTOS, i currently have a strange

> > problem with cycle-exact mode. The attached program gives different

> > results on my machine: 39 loops when cycle-exact is off, 30 when

> > cycle-exact is on. It is a simple test that just does a vr_recfl() on the

> > whole screen, running for 5 seconds. According to Christian, 39 is the

> > correct value on real HW, and on his machine he gets the same result in

> > Hatari, independent of the cycle-exact setting.

>

> I just noticed that you have prefetch turned off (bCompatibleCpu = FALSE).

> Note that in Hatari's fixup_cpu() function [custom.c], if cycle exact is

> specified, then prefetch is turned on. So if you do not have prefetch

> specified normally, turning on cycle exact will also turn on prefetch, and

> that will definitely affect your results, even on a 68000.

>

> Roger