Pi400 slow stuttery dremcast redream emulationI

luckyluca

Comparing the pi400 at stock against the pi4 at stock, I noticed the pi400 to produce stutter and slowdowns on Dreamcast games such as 18 wheeler on redream on the latest retropie.

Is this a known issue with Redream/Retropie that needs optimizing for the pi400 or something else?

Help would be most welcome
Thanks

mitu

@luckyluca said in Pi400 slow stuttery dremcast redream emulationI:

Is this a known issue with Redream/Retropie that needs optimizing for the pi400 or something else?

No, it's not a known issue. The Pi4 and Pi 400 are using the same image, and the Redream binary is the same for both - the Pi4 one. Are you sure you're running the same Redream version on the systems you're comparing ?

luckyluca

@mitu
I don't know the actual redream version, (how can I check?) but I've update everything including redream it via Retropie-Setup this morning and run it again. Stutter and slowdowns are still present.

Please see my videos depicting stutter (hope it's visible) on the pi400 stock (1.8ghz) with 4.7.1 and latest version of redream:

Against MagnusRC videos, using the pi4 stock (1.5ghz) with 4.7.1:

I would've expected, if anything, for the pi400 to perform better and be slightly smoother than the pi4, being clocked 20% faster.
What are your thoughts?

This is my first raspberry pi system, but seen how it (under)performs, I'm considering returning it for a pi4.

Thanks
Luca

P.s.
could you recommend a step by step guide to benchmark pi400,especially the gpu side?

mitu

@luckyluca said in Pi400 slow stuttery dremcast redream emulationI:

I would've expected, if anything, for the pi400 to perform better and be slightly smoother than the pi4, being clocked 20% faster.
What are your thoughts?

I don't see a visible difference, sorry. In your video, the emulator seems to be running at fullspeed (60fps), just like in the other video. The 2nd video doesn't show which resolution is used, you can try and lower your running resolution to 720p or 480p from the runcommand launch menu.

This is my first raspberry pi system, but seen how it (under)performs, I'm considering returning it for a pi4.

The Pi 400 is a higher clocked Pi4, I don't see how that would help.

luckyluca

@mitu

both are running at the same resolution and redream settings.

It is rather visible, the pi400 has microstutter, motion is not fluid, the pi4's motion appears fluid (disregard the fps counter as it is misleading). Besides, the pi400 should, if anything, be smoother being a faster clock, right?

I've updated a new video of the pi400, see for instance from second 16 until second 34:

I'm not saying it's not to be expected that some games can stutter, I'm just comparing apple for apple against the pi4. My main reason for getting the raspberry pi4/400 was to being able to play the Dreamcast system smoothly.
Regarding returning the pi400, I agree with you, it doesn't make sense being effectively the same machine, does it? Perhaps a driver/gpu issue with the pi400?

Can you recommend a good and simple benchmark I can run from retropie in order to test the pi400, especially gpu?

Thanks

dankcushions

there seems to be similar kind of stutter in your pi4 video. see 2:48 for example.

@luckyluca said in Pi400 slow stuttery dremcast redream emulationI:

Against MagnusRC videos, using the pi4 stock (1.5ghz) with 4.7.1:

luckyluca

@dankcushions You're right actually (I was focusing on the first portion of the video/game mainly).

But I'm not seeing the performance increase from the 1.5->1.8 clock though, but perhaps I'm expecting too much from the pi400 (I'm new to the Raspberry Pi, having transitioned from the Playstation Classic).

I'd still love to run a benchmark and compare it against other pi400 and pi4.

windg

If you are using different sd cards for pi400 and pi4, then try the sd card with the RetroPie, from pi4 to pi400 and test the game again.

dankcushions

@luckyluca mm the cpu is probably not the bottleneck. the pi4s cpu is quite decent. the gpu and the system bandwidth tend to be the bottleneck in GL applications.

~~you could try a system update:~~

~~sudo apt update && sudo apt dist-upgrade~~

~~that should get the latest stable mesa drivers (possibly an update since the image). as always, backup before any updates !~~
(ignore - upstream has not got update mesa yet)

mitu

@dankcushions said in Pi400 slow stuttery dremcast redream emulationI:

that should get the latest stable mesa drivers (possibly an update since the image). you can get the latest cutting edge mesa driver via the retropie package manager i believe, but not at my pi to get the steps for that. as always, backup before any updates !

That won't help, Redream comes with its own MESA driver for the Pi4 GPU.

@luckyluca Try lowering the resolution and see if it improves the stuttering you're noticing. Toggle the performance CPU governer in Runcommand's settings.
You can try lr-flycast instead of redream, it has several options for improving performance - including frame skipping if I recall.

dankcushions

@mitu said in Pi400 slow stuttery dremcast redream emulationI:

@dankcushions said in Pi400 slow stuttery dremcast redream emulationI:

that should get the latest stable mesa drivers (possibly an update since the image). you can get the latest cutting edge mesa driver via the retropie package manager i believe, but not at my pi to get the steps for that. as always, backup before any updates !

That won't help, Redream comes with its own MESA driver for the Pi4 GPU.

still? the author's performance tweak was accepted into MESA months ago, so i would presume they're not doing that anymore, unless they've made other changes i suppose.

mitu

@dankcushions Their version might include other optimizations, however the changes you mentioned have been included in Mesa 20.0, while Raspbian has only 19.3 in the official repository.

dankcushions

@mitu dang, you're right! i had no idea they were that out of date.

luckyluca

Update:
Thanks for the suggestions and tips, I'll need to build more confidence with the system first, as I'm new to the Raspberry Pi, I'll look into them in the near future. Regarding the emulator, I'd rather stick to Redream as it is an overall a better choice for Dreamcast games.

I'm talking to the Redream team and so far: somebody else noticed the same jitter/stutter on their pi400. Same jitter, albeit perhaps less frequently, is visible on the pi4 stock video provided by MagnusRC.

Pi4 stock on retropie, latest version, see 3min.30secs for jitter:

Pi400 stock on retropie, latest version, see sec.35 and again at 1min.26secs for jitter:

Thanks again, hopefully a new Redream build in the near future might improve things. Regarding overclocking, do you know what the default gpu clock is for the pi400/pi4?

mitu

@luckyluca said in Pi400 slow stuttery dremcast redream emulationI:

Regarding overclocking, do you know what the default gpu clock is for the pi400/pi4?

I think the default gpu_freq is set to 500 (Pi4), I assume is the same for Pi 400.