SNES on RetroArch (a faster SNES emulator)

[Rezzy-dev]

How is SNES currently performing on RetroArch? Do we have faster emulation than using the Snes9x4D standalone emulator on Miyoo? Are there any faster performing SNES emulator cores in RetroArch for Miyoo?

[thogi99]

The short answer is no. RetroArch cores are not faster than standalone for SNES

[Rezzy-dev]

I am interested to know which games this actually give a performance boost, because this is really unexpected.

In short? All of them (at least the ones that have speedhacks in the list and where the speedhack works)! Try The Lion King as a benchmark. Without the speedhack I'm getting some sound tearing, and the performance isn't nearly as smooth. With the speedhack I'm getting Sega Genesis (PicoDrive) level performance -- not just playable (20-30 FPS), but silky-smooth (30-60 FPS)!

One thing I've noticed, though, is that Snes9xD suffers from the same problem FCEUX and most other emulators suffer on this platform: between launches, sometimes less resources are allocated to the emulator than it needs to run smoothly, causing a visible performance hit with the FPS. Simply quitting the emulator and relaunching it fixes the issue, and performance is back to normal.

I'm guessing it has something to do either with the available RAM, or, more likely, it's some sort of bug in the SDL surface drawing/display in the Miyoo OS. Interestingly, with FCEUX I'm still getting the full framerate (FPS) showing even while what's actually displayed is clearly less in terms of performance. Which led me to think that the rendering and performance output from the software has not changed (not been impacted), but the drawing display refresh rate on the SDL surface has... 🤔

Because of this system-level bug, people can mistakenly get the impression that Snes9xD performs even slower than it does on its own, without the speedhacks (as I did the first time I tried to play games with the emulator)!

So it's a big mess in terms of keeping up with how it's performing. (With no fault lying with the emulator in this case.)

[jSTE0]

@m45t3r Thanks for replying and for making snes9x4d. At least this explains why it's now unmaintained, you might want to change the repository description so people don't send PRs 😄

snes9x4d is actually a mixture of many snes9x versions, not only the Snes9x 1.39

At least the rendering code seems to be from 1.39, the mode 7 bit anyway, hence I raised m45t3r/snes9x4d#9. As mentioned in that PR, I did try PGO once but couldn't get it as fast as your build (the buildroot now uses gcc-11.2 though, I think you used 10.1).

Maybe someone should clean it and upstream to RetroArch, it could be a good choice for some devices.

Without PGO it would still be slower than standalone and probably slower than snes9x2002, which already struggles with mode 7 titles. Maybe @neonloop might be interested as picoarch does use PGO.

if someone really did have some assembly optimizations done at at the snes9x2005 codebase, it should be easier to port them to snes9x4d.

There are some assembly optimisations in the picoarch fork of snes9x2005, ported from snes9x2002.

@Rezzy-dev

One thing I've noticed, though, is that Snes9xD suffers from the same problem FCEUX and most other emulators suffer on this platform: between launches, sometimes less resources are allocated to the emulator than it needs to run smoothly, causing a visible performance hit with the FPS.

I noticed that also with snes9x2002 on RetroArch. Sometimes restarting the process doesn't help and you have to reboot the device. Don't think it's a leak, it can happen on first boot. Probably something to do with the physical memory layout (mostly guessing, without profiling it's hard to tell). It does make benchmarking even more of pain than it already is.

[m45t3r]

Thanks for replying and for making snes9x4d. At least this explains why it's now unmaintained, you might want to change the repository description so people don't send PRs smile

Oh, now I see that you send a bunch of PRs there. Would really like to test them, but yeah, I don't have the device anymore sadly.

At least the rendering code seems to be from 1.39, the mode 7 bit anyway, hence I raised m45t3r/snes9x4d#9. As mentioned in that PR, I did try PGO once but couldn't get it as fast as your build (the buildroot now uses gcc-11.2 though, I think you used 10.1).

Yeah, like I said, the code itself is a bunch of many Snes9x codebases mixed together with some specific optimizations from the original creators of snes9x4d (that as I understand, originated as an faster/more compatible fork of Snes9x).

I think I eventually started to do PGOs with F-Zero, just leaving it to the intro (I run multiple times though, always changing one setting like disabling/enabling Stereo, disabling/enabling scale, changing sound frequency, etc.). Not sure if this helps.

Without PGO it would still be slower than standalone and probably slower than snes9x2002, which already struggles with mode 7 titles. Maybe @neonloop might be interested as picoarch does use PGO.

I know, but the point is mostly that snes9x4d is more compatible than snes9x2005. Some games run better on it.

There are some assembly optimisations in the picoarch fork of snes9x2005, ported from snes9x2002.

Huh... Those optimizations looks interesting. They could have a good performance impact, especially the ones related to GFX.

[jSTE0]

I think I eventually started to do PGOs with F-Zero, just leaving it to the intro (I run multiple times though, always changing one setting like disabling/enabling Stereo, disabling/enabling scale, changing sound frequency, etc.). Not sure if this helps.

I used the same title and intro (I think I read somewhere you used that) but I only ran it once. I think I left frameskip on also, oops (the game will be running slower anyway and skips more frames, which means the rendering code may not be optimised as much).

the point is mostly that snes9x4d is more compatible than snes9x2005. Some games run better on it.

Ah, I hadn't realised that, I admit I'm not an avid SNES gamer.

[jSTE0]

@m45t3r Thanks for merging my PRs. If I could trouble your for another one m45t3r/snes9x4d#11, I was holding that back until the others were merged.

[daFourch]

If you want PROPER perf for SNES, check DrPocketSnes for PocketGo, it makes wonders

[Rezzy-dev]

Review and how-to: https://www.youtube.com/watch?v=r6EbXLFyslc

Download link: https://www.dropbox.com/s/m3nbkaasjg45dcd/PocketSNES_PocketGo.zip?dl=0

[daFourch]

Let me know if you ended up using it

[Rezzy-dev]

Thanks. Will check it out and give it a whirl -- and let you know my experience/thoughts. But there's one big drawback here: the source code is not available for this build/release. Which means it works now, but who knows if it will continue to work in the future -- and no adjustments/modifications/updates possible to the software.

[daFourch]

That's indeed unfortunate. This version can't savestate, it's buggy. Someone (or the author?) made a fix for that, but in this version, you can't save settings...

[daFourch]

Snes emulation is not very good in RetroArch, unfortunately. Snes9x2002 core's performances are quite similar to standalone PocketSnes, but the frameskip option in the core are not working as well as in the standalone. It skips way too many frames, resulting in an unsusable feature in RetroArch.

[jSTE0]

I see you've raised libretro/snes9x2002#56, I've replied there.