Performance better at 128 buffer than 1024?? - Weird Issues

[GoodBear]

Hey all! 

Just got a new MacBook Pro - M2 96GB Ram, 4 TB SSD. Ventura 13.4, Logic 10.7.8. My settings are I/0: 256, Processing threads: 12 High Performance, Process Buffer Range: Medium. It's performing pretty well! 

I'm doing my best to make a 1600+ track composing template built for a more powerful mac studio work super well on this computer and, for the most part, it is! I am getting some weird issues though. 

I have quite a few plugins loaded in the session, possibly up to 3 per track, as well as busses with reverbs and track stacks with just as many plugins. One track may have up to 12 -15 plugins in its path. That considered, performance is great. No pops or clicks. My CPU on a heavy session is hanging out around 50-60% on most of the threads. The thread furthest to the left is hanging out at around 90%. I believe this is because of all the plugins, but I'm not sure. The furthest thread on the right though, (the live track thread) is doing incredibly well. Basically hovering at 10%. I'm definitely pushing this computer a bit passed what it's supposed to be doing, but eh, it's basically handling it great.

Here's my question - this template is absolutely performing better the LOWER my buffer size is set. It's really weirding me out. Its best performance by far is with the buffer size set to 256 or 128. When I try to set the buffer at 1024, the template basically falls apart. Pops, clicks, dropped samples. It's falling to pieces. I have absolutely no idea why this is. Any valuable insight here? I'd like to be able to kick my template into "5th gear" and set the buffer at 1024 so that I can get a few extra tracks in when absolutely needed. Or at the very least, I'd like to gain some understanding into what might be happening here. 

Any thoughts are absolutely appreciated. Thank you! 🙂

Edited June 20, 2023 by GoodBear

[David MacNeill]

I'd like to know how this works as well. It seems that no matter which buffer setting I use on my M2 Pro Mac mini, I get weird stops at about ten seconds into any session. I have to clear the error box and play the track from the beginning to get stability. After that little annoyance, I can usually get consistent playback and bouncing.

I have heard that M-series chips don't like high Logic buffer settings, but I've heard no reliable explanation why this is so or how to adjust for it.

[ozinga]

At few places I read that DAWs perform better at  lower buffers on Apple Silicon

Here is one from Ableton Page

https://help.ableton.com/hc/en-us/articles/5266527910812-Reducing-the-CPU-Load-on-an-Apple-Silicon-Mac

 

"How to Optimize Live's Audio preferences for Apple Silicon vs. Intel Processors? 

The relationship between real-time audio performance and buffer size changed with the introduction of Apple Silicon Processor's architecture. 

On Intel-based CPUs the following relationship in Live is as follows:

Smaller buffer sizes may result in higher CPU usage 

Larger buffer sizes may result in lower CPU usage

Contrastingly, on Apple Silicon CPUs:

Smaller buffer sizes may result in lower CPU usage 

Larger buffer sizes may result in higher CPU usage"

 

[gunbrenner]

I experienced something similar on an M1 mac mini, sometimes lower buffer sizes seems to perform a bit better. I had projects giving me playback issues that were somewhat gone after lowering the buffer size. 

I really don't know why or if it is my imagination 🤣

[GoodBear]

This is so fascinating! I'm gonna take my buffer size down to 64 and see what happens! lol. 

[GoodBear]

Alright all! This "myth" is basically confirmed in my mind. Here's ranked performance for buffer size from best to worst on my 1600+ track template (in a very full session) 

1. 64 
2. 256
3. 128
4. 512
5. 1024 & 32 (Tied for being absolutely and completely unusable) 

The buffer size common wisdom seems to no longer be "the higher it is, the better performance" but rather "test what works for the specific computer and session you're working with".

[des99]

I noticed early on that performance at low buffers was great on my M1 Pro, and I didn't need to set larger buffers as my projects grew toward the final mix stage, like I once had to - not only that, but there seemed no advantage at all to set larger buffers.

Maybe it's a consequence of the fast memory architecture on Apple silicon, that lower buffer sizes are so efficient, that you no longer gain any advantage with larger buffers.

[skillzmcgavern]

I've been trying this out myself and not having better results at lower buffers in general, but I'm using nearly 100% 3rd-party plugins/VSTs, although they're all Apple Silicon native. Some have oversampling that can't be turned off, which might be a special case; I'm not going to go crazy testing it but results could vary based on whether all plugins used are built-in Logic stuff.

[shapiro]

I definitely see the same effect on an M2 Studio Ultra. A 64 buffer is giving me much better performance than one set at 512

[JBberg]

I just discovered this too. It's great that low buffers work well. It becomes a problem when they aren't enough, because there's nowhere to go after that. I often get 100% spikes on one core even though the project plays at 50% average.

Edited January 31 by JBberg
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