Low framerate on main EmulationStation menu - Pi 4

rilight

@dankcushions: We're both having the same issue with the emulation tearing, so I think there must be some common factor. (Also, since my initial post in this thread I replaced my power cable and HDMI connector with official Raspberry Pi ones so I know that's not the problem.)

bluestang

I get the 30 FPS slowdowns in ES with the FKMS and KMS driver. I can not pinpoint what is causing the issue. Whether it’s the stock Mesa driver (v19.3.2.) or even the developmental Vulkan driver (has minor chgs to ogl) the issue is persistent.

stoo

@bluestang I'm sure it's the driver. I've found shaders are also slower on Pi4 than Pi3, and turning off Threaded Video in RA on Pi4 is a recipe for disaster.

I'm convinced the Pi4 graphics drivers aren't ready for prime-time.

Darksavior

Does ES use the mesa drivers? Maybe compile your own using the latest version like the redream devs have done. (I really have no idea how to do this but if anyone can, I'd love to know the test results)

stoo

@Darksavior I mean, it might not be the driver - I'm no expert at all.

I'm just kinda frustrated because my experience so far has been that the Pi4 doesn't exceed - or sometimes even match - the Pi3's graphics performance in some cases. I'm just venting.

It's times like this I wish I could code.

bluestang

@Darksavior said in Low framerate on main EmulationStation menu - Pi 4:

Does ES use the mesa drivers? Maybe compile your own using the latest version like the redream devs have done. (I really have no idea how to do this but if anyone can, I'd love to know the test results)

The developmental Vulkan driver has to be compiled and that has the latest mesa v3d and vc4 drivers and the issue still persists.

bluestang

@stoo said in Low framerate on main EmulationStation menu - Pi 4:

@bluestang I'm sure it's the driver. I've found shaders are also slower on Pi4 than Pi3, and turning off Threaded Video in RA on Pi4 is a recipe for disaster.

I'm convinced the Pi4 graphics drivers aren't ready for prime-time.

Yea there is an issue with this documented in the RetroPie GitHub - https://github.com/RetroPie/RetroPie-Setup/issues/3134 and upstream in RA - https://github.com/libretro/RetroArch/issues/10688

bluestang

I'm starting to wonder if the SDL2 build script with the isPlatform "rpi" && conf_flags+=("--enable-video-rpi") is the cause of the framerate drop in ES for the Pi 4.

The Pi 4 should not be using any of the "legacy" VC libraries in /opt/vc/ because the Mesa libraries are the default now. The Pi 4 is adopting the standard Linux APIs so it should be mirroring what the other SBCs are doing. This is why omxplayer has been deprecated altogether.

The VC libraries are there for "backward compatibility" but should not be relied upon moving forward. There have been several threads on the official Raspberry Pi forums about this.

@mitu @dankcushions @BuZz

BuZz

@bluestang your assumptions are incorrect. Check the sdl2 module history and our sdl2 branch.

bluestang

@BuZz said in Low framerate on main EmulationStation menu - Pi 4:

@bluestang your assumptions are incorrect. Check the sdl2 module history and our sdl2 branch.

I did take a look and even though the VC headers are moved temporarily the --enable-video-rpi still triggers an option that is not necessary for the Pi 4. (https://github.com/RetroPie/SDL-mirror/blob/retropie-2.0.10/configure#L19829) - see setup log here --> lines 332 & 333. The standard Mesa libraries/drivers that come w/ RPiOS know which API to use based on the overlay driver configured - i.e. FKMS or KMS.

From my understanding via the official RPi forums, the Pi 4 should be built with the preferred Mesa headers/libraries rather than the Broadcom VC ones. Meaning, for the Pi 4 the options should be --enable-video-kmsdrm and --disable-video-rpi. I made this change here --> Setup Log and didn't see any negative issues. I need to do more testing to see if this fixes the framerate drop entirely but initial results look promising.

The differences in the two drivers are FKMS still uses the Broadcom proprietary Dispmanx API and KMS uses the standard Linux KMS/DRM API. (FKMS is just a wrapper on top of Dispmanx) Compatibility for Dispmanx will still be available for the Pi 4, but it seems that it will be deprecated at some point in the future. Especially once the KMS driver is fully developed.

In 64-bit RPiOS you've probably noticed that the Broadcom VC headers are now located in /usr/include but the Broadcom specific libraries no longer are present. Developers should be using the standard Linux libraries aka Mesa ones just as you would for standard Linux development.

BuZz

@bluestang said in Low framerate on main EmulationStation menu - Pi 4:

Developers should be using the standard Linux libraries aka Mesa ones just as you would for standard Linux development.

We are.

bluestang

@stoo @Darksavior what is your result if you pass the cmd line option emulationstation --vsync 1?

Darksavior

@bluestang No change. fkms or kms.

stoo

@bluestang yeah, seems exactly the same

bluestang

@stoo @Darksavior Can you confirm that you can get the 30 fps framerate drop immediately if you invoke the screensaver for 5 secs and then exit to go back to the main menu?

Also, I enabled the Enhanced option of the Power Saver Mode in Other Settings and although I still get the fps drop, ES will go back to 60 fps without having to go into RA separately.

This is a weird bug for sure - @BuZz

BuZz

It's primarily a driver/firmware issue or maybe an overlapping issue with SDL2 as the sdl2 Kms driver has some issues. I thought I got some improvements disabling the WSOD / dynamic gpu texture loading code (which does have one bug, in that 0 should be unlimited but isn't). But I'm actually looking into that currently as well as SDL2 due to upstream changes.

Our sdl2 includes the old driver, but isn't used for ES on the rpi4. As GL contexts don't work on the RPI4 on dispmanx, there wouldn't have been any display at all. They co-exist together in our SDL though.

Primarily for rpi3 etc. Our sdl2 will work in both old videocore via dispmanx or via kms on a rpi3.

Newest Mesa doesn't fix the slowdown btw. Before people said switching to the Kms driver sorted it. I can't remember but I'll retest.

bluestang

First off I'm sorry for bombarding your PRs with my nonsense. RA made it possible to use the developmental Vulkan driver post v1.8.8 and I was excited to try it out. Just in what I've been able to mess around with, it seems to provide a few improvements.

@BuZz said in Low framerate on main EmulationStation menu - Pi 4:

It's primarily a driver/firmware issue or maybe an overlapping issue with SDL2 as the sdl2 Kms driver has some issues. I thought I got some improvements disabling the WSOD / dynamic gpu texture loading code (which does have one bug, in that 0 should be unlimited but isn't). But I'm actually looking into that currently as well as SDL2 due to upstream changes.

Lowering the resolution to 720p does not exhibit the framerate drop but that is not the ideal solution. Would compiling the latest release of SDL2 with the neon optimizations help?

Our sdl2 includes the old driver, but isn't used for ES on the rpi4. As GL contexts don't work on the RPI4 on dispmanx, there wouldn't have been any display at all. They co-exist together in our SDL though.

Primarily for rpi3 etc. Our sdl2 will work in both old videocore via dispmanx or via kms on a rpi3.

Although the Pi 3 and Pi 4 share the same driver names, which probably leads to more confusion for everyone, they do not follow the same rules when it comes to 3D and video composition.

Newest Mesa doesn't fix the slowdown btw. Before people said switching to the Kms driver sorted it. I can't remember but I'll retest.

I can confirm that when KMS was first exposed in the 5.4 kernel it did fix the issue but that was many moons ago. An update at some point led to the regression, but that may have just been luck as the KMS driver was missing functionality and still does.

Swampy

@bluestang said in Low framerate on main EmulationStation menu - Pi 4:

I can confirm that when KMS was first exposed in the 5.4 kernel it did fix the issue but that was many moons ago. An update at some point led to the regression, but that may have just been luck as the KMS driver was missing functionality and still does.

I have had the same experience.

bluestang

I couldn’t find this issue at first but I did remember reading at some point. Seems relevant to the issues described in this thread.

https://github.com/raspberrypi/firmware/issues/1154#issuecomment-544428380

GreenHawk84

I am glad there is interest in this, thanks for the updates !