Re: [hatari-devel] DSP performance

[Eero Tamminen <oak@xxxxxxxxxxxxxx>]

Hi,

On tiistai 30 kesäkuu 2015, Nicolas Pomarède wrote:
> Le 30/06/2015 22:45, Eero Tamminen a écrit :
> > 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)

Program binary being loaded to TT-RAM doesn't change speed.

Using MMU (i.e. non-cycle accurate CPU emulation), changes
numbers to:

MMU WinUAE CPU core: FPU 431 Mhz, DSP 59 Mhz, CPU 81 Mhz

This is pretty close to oldUAE numbers except for DSP...


> > 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.

FPU was closer than oldUAE i.e. ~200Mhz when you first integrated
new WinUAE (without Laurent's timings) and now it's ~4x faster.
I was just wondering whether something drastic had happened to
*WinUAE*'s FPU emulation since last fall?


	- Eero