Can't get FS-UAE to run faster than WinUAE

[ral-clan]

Hi,

I've been using both WinUAE and FS-UAE under Linux (Lubuntu 20.04) for several years, but am gradually wanting to move away from WinUAE (which has to run under Wine) to the native FS-UAE. I don't really play games under Amiga emulation but rather use my emulated Amigas for productivity work (graphics, music composing, etc), so software speed is important (i.e. when rendering 3D models). I've set up as close a virtual Amiga "configuration" on both emulators as I can; essentially a virtual A4000 NTSC running OS3.9 with 68040 and 2MB CHIP RAM, 128 MB Fast RAM. JIT is enabled on both configurations, along with high chipset compatibility (accurate) emulation.

For the most part both emulators run super fast on my i5 computer (much faster than a 68060 Amiga). However, I'm finding certain graphical functions of AmigaOS under FS-UAE are orders of magnitude slower than WinUAE. Where I first noticed this is in Lightwave. Refreshing of the wire-frame models after each move take 5 to 10 seconds to re-render under FS-UAE whereas under WinUAE they only took fractions of a second. I ran AIBB benchmark on both emulators. FS-UAE performs as fast or even faster than WinUAE on most tests, EXCEPT two which are super slow compared to UAE. These test are:

ElipseTest and TGTest

For some reason these tests are barely faster than a real hardware A4000.

Can anyone suggest anything I can do or any information I can provide to this forum that would help diagnose why these two tests are super slow? I can upload my config files for both emulators, for example.
I've attached screenshots the two tests where FS-UAE really stalls:

[FrodeSolheim]

Hi, I think the most likely reason for the slowdown is that the JIT compiler falls back to interpreter mode during (parts of) the EllipseTest and TGTest. So maybe these tests use a CPU instruction which isn't JIT-enabled in FS-UAE. We should be able to figure this out, but it's not easy for you to test for yourself unless you're a programmer.

But first off, you could check the speed comparison against (both) WinUAE 3.2 and 3.3 (or only WinUAE 3.3.0 beta 2), since FS-UAE 3.0.5 shares emulation code with WinUAE 3.3.0 beta 2. If the older WinUAE versions still performs orders of magnitude faster on these tests, then it makes sense to debug the JIT/CPU instructions being used, further.

(It could also be related to floating point calculations, where I know that at least some functions are not JIT-enabled, but I think only the "yellow tests" use floating point numbers?)

[FrodeSolheim]

Actually, if these drawing functions use RTG, that might also be a place where WinUAE might be faster in some circumstances. I know WinUAE has one optimization for RTG which is not currently supported in FS-UAE. So maybe you can run the tests in non-RTG mode and see if that makes a difference?

I would test this first...

[jbl007]

It's about blitter speed. If you enable immediate blits emulation it will fly.

accuracy=-1

or

uae_immediate_blits=true

[FrodeSolheim]

Ah, good point. I assumed for a second there that the (effective) configurations where identical, should have asked for logs first

Try jbl007's suggestion first

[ral-clan]

Originally Posted by jbl007

It's about blitter speed. If you enable immediate blits emulation it will fly.

accuracy=-1

or

uae_immediate_blits=true

Thank you! The "accuracy=-1" parameter solved it (the "uae_immediate_blits=true" did not).

Using the accuracy parameter FS-UAE performs almost as fast as WinUAE in the ElipseTest (about 10% slower) and more that TWICE as fast as WinUAE in the TGTest.

Lightwave model refreshing is now almost instant!

I really appreciate the helpfulness and quick responses provided by the knowledgeable people on this forum!

As an aside, I can now almost entirely switch to FS-UAE. FS-UAE is now a better solution for me when doing visual (graphic) art. I will have to keep WinUAE installed just for music composing, as I need MIDI to function. However, I read that MIDI will come with FS-UAE 4.0 ---- really looking forward to that as it will be the day when I can fully migrate to FS-UAE (any news on when that will come?).

Thanks everyone!