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