Real CPU Usage vs. Pro Tools System Usage Window

[tbonesteak4dinner]

Hello everyone,

I have a question regarding how Pro Tools 11 calculates system usage. I'm working on a fairly heavy project. My system hardly slows down for anything so when it choked during a couple sections I broke out the diagnostic tools.

HWinfo64, CPU-Z, CoreTemp, etc. all show CPU usage as peaking at 55% at the heaviest part of the project, otherwise it stays in the mid 30% range. The Pro Tools system usage window shows sustained CPU usage of over 100% (bar turns red) during the heaviest part, and otherwise will hang around 50-70%. In addition, I confirmed there is zero thermal throttling going on.

I'm pretty confident in my build and have run it through the whole gamut of Prime95, IBT, and other tests and I've seen it get stressed to its limits. WIth this project, it's just getting to the point where the processor should begin to work, yet Pro Tools seems to think it's hitting its limits and is acting accordingly.

First thing I could point to, and maybe something I don't entirely grasp, is my interface's impact. I'm using an old 003 rack and believe me it's first on the list to upgrade. Is this my bottleneck or did I miss a fairly rudimentary setting somewhere?

Thank you very much in advance for any insight!

Relevant Specs:
Core i7-3820 (Overclocked to 4.625Ghz, stable)
16GB 1333 DDR 3 Memory
Separate SSDs for OS, Samples
Separate HDDs for PT Projects, Storage, etc.
Digidesign 003 Rack (firewire 400, legacy drivers as recommended)
Pro Tools 11

[Darryl Ramm]

What is actually happening? You describe lots of stuff but not what the exact issue is. Nobody can guess what you mean by "it's hitting its limits and is acting accordingly."

System wide CPU usage numbers tell you next to nothing useful, per core numbers tell you more. Even then if you are getting CPU errors you don't need to look at the meters. Just try solving the problem.

Turn off "ignore errors" and see what exact errors get thrown.

Always suspect plugins.

Standard troubleshooting:
- Trash prefs
- Pull all third party plugins out of the plugin folder
- Look for denormalization problems with plugins, like Sansamp, D-Verb, etc. don't use them or stick a dither plugin in front of them. All widely discussed on DUC in the past.

[tbonesteak4dinner]

Originally Posted by Darryl Ramm

What is actually happening? You describe lots of stuff but not what the exact issue is. Nobody can guess what you mean by "it's hitting its limits and is acting accordingly."

System wide CPU usage numbers tell you next to nothing useful, per core numbers tell you more. Even then if you are getting CPU errors you don't need to look at the meters. Just try solving the problem.

Turn off "ignore errors" and see what exact errors get thrown.

Always suspect plugins.

Standard troubleshooting:
- Trash prefs
- Pull all third party plugins out of the plugin folder
- Look for denormalization problems with plugins, like Sansamp, D-Verb, etc. don't use them or stick a dither plugin in front of them. All widely discussed on DUC in the past.

Sorry, I'll try to be more clear. I've already done the basic troubleshooting just to get that little forum favorite out of the way. Believe me I do know it's important to start there.

What I mean is that Pro Tools will audibly click, pop, or stutter as if it's hitting 100% overall CPU usage (which it thinks it is), but actual system diagnostics show no core hitting anywhere over 60% during a spike, and overall usage being much lower than Pro Tools reports, essentially half as much at 55%. Pro Tools does not throw any errors with "ignore errors" turned off. With it turned off, Pro Tools will stutter or halt for split second, and with it turned on, it will just click/pop and move on.

Per core utilization in Pro Tools appears to favor cores 4 and 5. These will sit around 60% during the heaviest parts and stay there, with the other six cores sitting around 10% or so. In hwinfo64, core 6 and 8 will sometimes spike, but overall the load is distributed fairly evenly between the first thread of each core, as you would expect with hyperthreading. Regardless, it's well below any threshold for throttling the CPU. Those percentages are that single core's resources and they're nowhere close to maxing out.

[tbonesteak4dinner]

I should also note that Pro Tools reports an idle usage of 25% or so, while any other tool, including task manager, reports around 6%.

I guess the real question is how does Pro Tools calculate CPU usage? It's clearly different than the OS or any diagnostic tool. Is it assigning itself a smaller pool of CPU resources and treating it as a new maximum?

[Darryl Ramm]

OK stop looking at the meters. This is not helping in any way. And discrepancies are usual.

You need to finish troubleshooting this. Find what exact plugins are causing this/burning CPU. Even if not instantiated, start by pull all third party plugins out of the plugin folder. Is this happening to just one session, etc.

Do all troubleshooting with "ignore errors" not checked.

[tbonesteak4dinner]

Originally Posted by Darryl Ramm

OK stop looking at the meters. This is not helping in any way. And discrepancies are usual.

You need to finish troubleshooting this. Find what exact plugins are causing this/burning CPU. Even if not instantiated, start by pull all third party plugins out of the plugin folder. Is this happening to just one session, etc.

Do all troubleshooting with "ignore errors" not checked.

Opened another recent project with the same results. Pro Tools sits around 50% CPU, OS reports 15-20%. Again, I don't get errors with "ignore errors" unchecked.

Seems to be related to a Serum synth with high polyphony, but that only complicates things. I'm fully aware that synths like this are heavy, but there is still the reality that from an OS perspective it's barely beginning to push my system, yet Pro Tools thinks that it's out of resources. I already know I'm going to have to freeze the track, but that still doesn't get me any closer to an answer.

Why does Pro Tools think it has about 50-60% of the resources that it actually does?

[tbonesteak4dinner]

I really appreciate the help so far.

To do as much troubleshooting as I can, I tried swapping interfaces and started playing with the playback engine buffer. The issue actually improved as the buffer went down, so much so that on either interface, I could run the buffer at 64 samples and leave ignore errors unchecked without any audible issues. CPU in Pro Tools maxed out at 93% instead, which is better but still insanely high compared to the OS reading. This leads me away from a CPU issue, as that should have made things worse. The OS reading is always more or less the same as well, regardless of the changes I make in Pro Tools.

Looks like we're left without the old option to change the CPU percentage to devote to plugins, and things are worse when dynamic plugin processing is turned off for sure. I don't know how the new Pro Tools allocates resources, but I'm starting to think it gives itself a smaller pool for plugins and I really wish that setting were visible so I could confirm.

Following this I disabled hyperthreading as a longshot, which improved Pro Tool's idea of CPU usage by a few more percents, but I'm still staring at this 45-50% gap between what Pro Tools and my OS thinks is going on.

[Darryl Ramm]

Don't forget to turn off dynamic plugin processing (should always be off).

[tbonesteak4dinner]

Originally Posted by Darryl Ramm

Don't forget to turn off dynamic plugin processing (should always be off).

Yep, just said that I tried that. It was actually worse when it was off. Ah well, I guess I'll wait for others to chime in and open a case with Avid.

Thank you for your assistance thus far.

[tbonesteak4dinner]

Making headway. I'm posting here incessantly because this was supposed to be my weekend project so this is what I'm doing instead. Ha. I keep telling myself it's funny...

I found out if I record arm ANYTHING then CPU usage jumps up to 100% (30% in Windows). Definitely a software issue and definitely inside of Pro Tools. If I remove (not bypass) Ozone on the master it only goes up to 40%. Further if I disable QL spaces on the reverb auxes it only goes up to 15%. The fun part is if I remove all virtual instruments and leave Ozone, etc., CPU usage does not change at all when record arming. This is only if I remove ALL of them - it's not tied to a single manufacturer. I tried systematically removing each from the plugins folder and trashing prefs in between with no luck. This is a huge problem as I need them record armed and playing back live during recording, meaning an overhead of 40% CPU usage.

I found a workaround and possible explanation here: http://duc.avid.com/showthread.php?t=380961

By setting my processor affinity on Pro Tools to ignore core 1 entirely (second core and it's accompanying thread) and setting my buffer to a whopping 2048ms (it's all sequenced so actually no big deal), then I can get the project to hang out just under 100% CPU load in Pro Tools when record armed and playing back input. This is completely ridiculous. It still hammers that core for whatever reason, but telling it to not process on the ones it seems to like spreads the load more evenly everywhere else.

Absolutely silly resource management. I'm going to test with another DAW tomorrow and see how it compares.