Re: [hatari-devel] DSP performance

[Laurent Sallafranque <laurent.sallafranque@xxxxxxx>]

I was a bit lazy while coding the static table, and I used the same 
value for all the addressing modes of the FPU cycles.
That's why many FPU cycles were wrong, but not so much.

Example :

/*1821*/    {6,    0,     20,0,1,0,    22,0,1,0},    // FScc.L 
#<data>.W,(An)
/*1822*/    {6,    0,     20,0,1,0,    22,0,1,0},    // FScc.L 
#<data>.W,(An)+
/*1823*/    {6,    0,     20,0,1,0,    22,0,1,0},    // FScc.L 
#<data>.W,-(An)
/*1824*/    {6,    0,     20,0,1,0,    22,0,1,0},    // FScc.L 
#<data>.W,(d16,An)
/*1825*/    {6,    0,     20,0,1,0,    22,0,1,0},    // FScc.L 
#<data>.W,(d8,An,Xn)
/*1826*/    {6,    0,     20,0,1,0,    22,0,1,0},    // FScc.L 
#<data>.W,(xxx).W
/*1827*/    {6,    0,     20,0,1,0,    22,0,1,0},    // FScc.L 
#<data>.W,(xxx).L


It would be simple to add the  correct values now, but the static table 
won't be the futur of hatari, so I don't do it.
But I can compute the values if one need them to compare with the new 
core instruction cycles.

That's why old cpu timings were wrong with the static table

Laurent




Le 30/06/2015 22:57, Nicolas Pomarède a écrit :
> Le 30/06/2015 22:45, Eero Tamminen a écrit :
> > Hi,
> >
> > For references, here are Centurbo bench results:
> >
> > Today WinUAE CPU core: FPU 812 Mhz, DSP 57 Mhz, CPU 27 Mhz
> > Dec WinUAE CPU core: FPU 153 Mhz, DSP 57 Mhz, CPU 172 Mhz
> > Old WinUAE CPU core: FPU 221 Mhz, DSP 32 Mhz, CPU 15 Mhz
> > Old UAE CPU core: FPU 403 Mhz, DSP 32 Mhz, CPU 78 Mhz
> > (moving mouse drops FPU and CPU numbers slightly)
> >
> > I.e. compared to old WinUAE core with Laurent's timings,
> > current CPU runs 80%, DSP 78% and FPU >3x faster.
> >
> > DSP timing being derived from CPU would explain why it's
> > faster by same amount as CPU, but why FPU is now so much
> > faster?
>
> Hi
>
> haven't look in detail, but AFAIK fpu emulation is not cycle exact in 
> lastest WinUAE and most fpu opcodes take a very small number of cycles.
>
> Maybe it was a bit closer to real thing before, but it was wrong anyway.
>
> Nicolas