Plugin CPU usage: 10 on 1 track vs 1 on 10 tracks

[685]

Maybe this is old information but I wanted to understand why.


Inserting 10 plugins on 1 track produces a much higher CPU usage compared to inserting the same 10 plugins on 10 separate tracks (one plugin on each track). I can reproduce it on two different Mac computers using Ultimate 2021.7 and/or 2021.12


Thanks

[Darryl Ramm]

Why does this matter? What actual CPU errors or other problems are you getting?

What are you looking at to determine this? If you can explain to me what the Pro Tools CPU meters are showing exactly and how they are measuring this exactly I'd sure appreciate that. Especially given that half the CPU cores don't actually exist. ¯\_(ツ)_/¯

Plugins inserted in a chain on one signal path will tend to run on the same CPU core for efficiency/cache locality/latency reasons. That's a good thing.

Plugins on different signal chains will float around more on different cores. And maybe more likely to be smeared into the noise.

How accurately any of this is reported is a real question.

But it's all likely a waste of time, unless you have problems, and even then looking at meters is unlikely to help. The way to solve most problem seen in CPU meters is stop looking at the CPU meter.

[685]

Why does it matter? Because I was getting CPU errors while testing the Lexicon PCM update. That's why SMH.

One of the Plugins would not allow Protools to play at all but the others ran ok with 1 inserted so I added more reverbs to see what would happen. During the testing I noticed the differences in CPU usages depending on where I inserted the plugins. Protools ran smoother with 1 plugin on different tracks and the CPU usage was lower. 5% vs 32%

I thought it was just the Lexicon plugins but the same thing happened when I used other plugins. Much lower CPU usage when the plugins were spread out over 10 track vs all 10 plugins on 1 track. Changing the buffer settings did not change the results.

Originally Posted by Darryl Ramm

Why does this matter? What actual CPU errors or other problems are you getting?

What are you looking at to determine this? If you can explain to me what the Pro Tools CPU meters are showing exactly and how they are measuring this exactly I'd sure appreciate that. Especially given that half the CPU cores don't actually exist. ¯\_(ツ)_/¯

Plugins inserted in a chain on one signal path will tend to run on the same CPU core for efficiency/cache locality/latency reasons. That's a good thing.

Plugins on different signal chains will float around more on different cores. And maybe more likely to be smeared into the noise.

How accurately any of this is reported is a real question.

But it's all likely a waste of time, unless you have problems, and even then looking at meters is unlikely to help. The way to solve most problem seen in CPU meters is stop looking at the CPU meter.

[Darryl Ramm]

So nowhere is looking at meters here likely to help you.

There is a standard approach to troubleshooting. Start under "help us help you" up the top of each DUC web page. And run the drill. It may seem silly, but just get used to grinding that list every time. It's largely a waste of time to be asking questions here until you've done that basic stuff. Maybe you have, we have no clue.

Make sure you...

trash prefs (make sure you are doing this correctly for your OS/Pro Tools version)
check your system is fully optimized
What happens if you set the largest IO buffer size?
Remove all .aaxplugin files from the plugin folder (Pro Tools will automagically put back the standard plugins automagically). If Pro Tools works fine like that add back one of these suspect .aaxplugins at a time and test again.
And it's not just about what plugins are instantiated in an insert, it's what plugins are installed in the plugin folder even if they are not being used, start by getting them all out.
Make sure disk cache is enabled (set to a size not "normal").
Try starting with new empty session.
Try using a new admin account.
Try with Built-In Output as the playback engine.

Can't fix the issue/isolated to a specific plugin ... is that claimed to be supported on that Pro Tools and OS version? What exact plugin version? Is that the latest/supposed to be compatible? Try downloading a new installer even if it looks an OK version. Other plugin users reporting problems? Contact the plugin vendor for support if you suspect it's having problems... the plugin vendors are more likely to be responsive than Avid support, and often in the right place to fix issues. But what can I say... issues with Lexicon plugins might not be a huge surprise.

AAE CPU errors are really caused by latency, often very brief latencies, not directly CPU load, there is some correlation, but the latencies caused by CPU problems is often not correlated to stuff you can see on the meters. Maybe a rare occasion meters give clues is if they peg or fluctuate in odd ways.. in past times showing for example the CPUs being saturated by de-normalization behavior in plugins.

And like all other users asking for help, you need to provide your basic systems info, what exact Mac computers, what macOS software versions (lots of issues with say Big Sur), playback engine/interface, IO buffer size, etc. stuff described under "Help Us Help You". Also confirm the exact error code/number you were getting. And get "ignore errors" not checked while you debug stuff... you want to see all errors possible.

[685]

Simply answer for a simple question.

That’s normal behavior. A single audio track can only operate on one CPU core, so with lots of plugins on one track, you can easily max out a single core. Putting one plug-in on many tracks load balances the CPU usage across many cores.

[Darryl Ramm]

As I said...

Plugins inserted in a chain on one signal path will tend to run on the same CPU core for efficiency/cache locality/latency reasons. That's a good thing.

Plugins on different signal chains will float around more on different cores. And maybe more likely to be smeared into the noise.