Software Support > GroovyMAME
GroovyArcade live-CD 2022 (collaborative effort)
intealls:
--- Quote from: Substring on September 22, 2024, 04:28:19 pm ---The RT patch exists for years already, and was simply just not merged in the kernel. Quite some work has been made to have that RT patch merged for good inside the kernel. But maybe 2 years ago, Calamity made some tests with that patch: nothing better, nothing worse.
--- End quote ---
I'm seeing benefit from the -rt patches when maximizing framedelay and minimizing audio latency as outlined in this post: https://forum.arcadecontrols.com/index.php/topic,160023.msg1770960.html#msg1770960 . The incoming/outgoing samples plot should be a continuous line without jumps, the -rt performs much better than the one without. This is still valid for me a couple of months down the line.
But you really have to measure it (and do that over a longer period of time, and examine video as well as audio). However, in practice I think the only way anyone would really notice would be the audio pitch shifts resulting from skipped frames. There might be drawbacks given all the hardware GA runs on, but for me whenever updating GA I build a new -rt kernel to go along with it and install that manually. But there is probably only a benefit if you really, really want to do something about those last couple of milliseconds of latency, and it could perform worse for some hardware.
I've also attached a new version of the rate filter (still only PortAudio) which should reduce audio pitch shifts with -syncaudio and high frame delay levels in case anyone wants to try it.
edomatic:
Hi Intealls,
Could you elaborate on your findings with framedelay and where you noticed improvements using the RT kernel for GA.
You say you are in a couple of months, where do you notice the gains using RT?
intealls:
--- Quote from: edomatic on October 24, 2024, 01:15:46 am ---Hi Intealls,
Could you elaborate on your findings with framedelay and where you noticed improvements using the RT kernel for GA.
You say you are in a couple of months, where do you notice the gains using RT?
--- End quote ---
Hi edomatic,
First of all, I'm pushing this system (an i5-46x0k@4.5 GHz) to its absolute limits. I've increased the frame_delay granularity to 100 instead of 10, so I get a 10x resolution increase in frame delay granularity.
I can observe two things:
* For whatever reason, it seems like audio update routine (callback) sometimes does not come at its required interval without -rt, it doesn't happen often, but it happens. So when the sound system should fetch samples, it doesn't. I'm not sure it's down to the particular hardware I'm using, but -rt seems to help here. I've attached the plots again (less cluttered) and this can be seen as a downward step in the plot.
* Frame delay will block until the last possible moment before emulating the frame and vblank, and as such the time after releasing frame delay is super sensitive if we don't want to miss vblank. -rt seems to perform better in this regard. Missed vblanks can be seen as upward steps.
BUT - I've spent a _lot_ of time tweaking this system, enabling the -rt patches might actually degrade performance for a given hardware configuration. But for my particular hardware and software configuration -rt helps.
edomatic:
Interesting stuff intealls!
Have you by any chance checked in with Calamity on his view on this?, i believe i read a comment from substring saying calamity experimented with this about 2 years ago ? but a lot can change in that timeframe off course,(patches,updates,improvements..).it looks like you are on to something.
I would love to test this rt kernel out to see what the impact is on the games in terms of framedelay/audio latency performance.
I myself am on a i7 4790k with substring’s latest GA build running in pretty much vanilla.i have not experimented with rt kernels, is it hard is to set that up or modify /add that functionality to the existing build i have?
Substring:
In terms of input latency, Calamity said the RT patch brought nothing when he tested. But I shouldn't speak on his behalf ;)
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