Possible bug on Punch-Out!!! - need verification

themanuel · 05-25-2018, 12:13 PM #1

Since my computer seems to have frequent issues with Dolphin but occasional I identify real bugs, I would appreciate it if somebody can give this a quick test.

On Punch-Out!!!, when I use either a high resolution (3x) or MSAA 4x, the game seems to work fine until a fight begins. As soon as the pre-fight scene appears, when the camera pans around the arena, the game starts stuttering massively and becomes unplayable. This is not like a shader compilation stuttering but a constant slideshow with garbled sound. I'm using DirectX 11.

Is somebody can confirm this, I will issue a bug report but I don't want to send the devs on a wild goose chase if it's just me.

**KHg8m3r** · 05-26-2018, 04:53 AM #2

Sounds like you're hitting a bottle neck. If you bring down the enhancements does the slowdown go away?

mimimi · 05-26-2018, 05:20 AM #3

Does the game require efb2ram? It does sound like the scene in question puts a lot of strain on the gpu. Increasing the IR or enabling AA multiply the GPU requirements, which would explain lag, if the gpu load in that scene is higher to begin with.

If the game does not require efb2ram, it should run fine with efb to texture only enabled, as efb2ram increases the gpu requirement by a lot, because the rendering of efb copies can't be done async and the gpu has to render one, stop, wait and then do the next one.

Or it could be that the game requires efb cpu access, which is very similar to efb2ram, which also increases the gpu requirement a lot. If it's efb cpu access though, you have might have luck and it works better with another graphics backend, while efb2ram should hit all backends about equally. I think the different backends still have different strategies on how to deal with cpu efb access, but it's planned to unify this, so it works the same on all backends.

The solution to efb2ram killing performance is being worked on, but since it's a very difficult task, and only one person is working on it, it's progressing slowly:
https://github.com/dolphin-emu/dolphin/pull/6128
Don't expect that to be fixed anytime soon, it would be one of the huge features like zfreeze was or xfb to texture.

themanuel · 05-26-2018, 06:15 AM #4

Thanks. Not too worried as I just finished the game but felt an obligation to report it if it was a bug. My video card is not state of the art but plenty powerful enough for Dolphin. Same with my CPU. However I have been having what seem like unique issues so I was hoping somebody else would try it and see. I had played this game months before with the same enhancements and not run into this issue so something might have changed. I’ll play around with the different EFB and XFB options.

**KHg8m3r** · 05-26-2018, 06:38 AM #5

The GPU load of Dolphin has increased due to the increase in accuracy. That may be why you can't have the same level of enhancements as previously.

However, do you see the same slowdowns in the Vulkan backend?

themanuel · 05-26-2018, 02:21 PM #6

Good call. It does not happen with Vulkan. This is similar to the F-Zero GX slowdown issue with the heat blur effect in Sand Ocean, which also works fine with Vulkan. The problem with Vulkan is that the ubershaders don't work well. By the way, with Ishiiruka, Punch-Out!!! does not have these slowdowns. I think it is because of a hack it has called "Fast EFB Access".

I should have mentioned that these slowdowns persist throughout the whole fight, not just the scene I described. The graphics in this game are quite simple compared to say, SMG2 or Metroid Prime Corruption, both of which I can run very well. I don't know what causes this game to be so demanding.