Re: [hatari-devel] Hatari data cache tests

[Nicolas Pomarède <npomarede@xxxxxxxxxxxx>]

Le 18/06/2015 22:46, Douglas Little a écrit :
> I should add - I think its better to use idealized timings to check the
> CPU ops, cache, and head/tail timings are accurate.
>
> Later it would be more interesting to use real F030 video modes to get
> bus performance more accurate... but even at that it would be some kind
> of approximation I suppose.

For now, it's a kind of "chicken and egg" problem : we need correct cpu 
emulation to get correct video timings (because in Hatari it's the CPU 
clock that drives all other components), but we also need correct video 
emulation to know how the videl's bandwidth affects the cpu by slowing 
down RAM accesses.

So yes, we need to start with the simplest possible case, where we know 
videl doesn't affect the cpu. When we get correct cycles in all cases, 
then my idea would be to have an approximation of how many percents each 
video mode takes from the CPU (taking into account the border size and 
the resolution). For example, slowing down cpu memory accesses every 10 
or 20 cycles if video uses 256 colors.

This is something that is documented for Amiga, where slowdown can be 
computed depending on DMA/video accesses, but for the Falcon, I'm afraid 
this was not fully documented, so this will require a lot of tests.

By the way, could you post your results when running your program on a 
real HW ?

Nicolas