Windows 10 MMCSS 32-thread Limit

In reference to this KB article…

Is this new in the Creator’s Update? Was it carried over from previous versions of Windows 10? Has it been changed in Creator’s Update? I don’t understand how 32 real-time threads minus 4 non-audio threads running results in setting 14 logical cores. Shouldn’t we be able to get 28 logical cores? I’m talking 14 hyper-threaded or 28 non-HT cores. I don’t think I’ve run into this issue at all on Windows 10 and my Xeon E5-2687W v4 which I have running 12 hyper-threaded cores for a total of 24 logical cores. Is there a typo in this article? Is Microsoft planning to revert that behavior to the previous Win 8.1 behavior?

I noticed the MMCSS check tool still shows a 32-thread limit in Creator’s Update. What does Cubase do with a 14-thread limit once you hit a track count of 15 (or maybe 14 since I’m guessing the master channel needs a thread for mix-down)? Still no registry tweak to unlock this thread limit?

Hello Steinberg,

can you please comment on the original post?
It bad you leave us stuck with this issue, not providing any further information if the kb-article is correct or not wrt 14 logical cores.

Also you should be able to get some indication from MS, whether this will be fixed or not.

It’s since Windows 10, and the article is correct.

I’m confused as my Ryzen 1700x is about to come.
mmcss-test.exe shows ´threads with MMCSS priority: 32´
Windows 10 Home build 1709 (just updated)

Does it mean I should’t worry about hacks?

I don’t know what you mean by “worry about hacks”. You will have 16 logical cores on Ryzen 1700X, so you should be fine.

I was initially confused about the KB article because it says you get 28 MMCSS threads but they want you to limit Cubase to 14 because they say it spawns 2 threads per. This was not my experience. I had the tweaked file the KB article offered loaded on my machine and watched it only use 14 of my 28 logical cores. I edited that file to limit to 28 threads instead of 14 and watched it start using all 28 logical cores. In fact, I specifically bought an 19-7940X for my audio workstation because of this limit. I really hope Microsoft ups that limit or gets rid of it at some point. I would hate to be limited to 28 threads forever (last version of Windows… :unamused: ).

I mean disabling two logical cores, sort of a hack. Very confusing stuff, anyway I’m assembling the Ryzen today and test it for myself. Thanks.

I’m confused by the terminology people use in this thread

We have a CPU, that CPU has physical cores, these consist of 2 virtual cores a.k.a. “threads”
In my my case I have a Core i9 7940x, this CPU has 14 physical cores / 18 virtual cores/threads
The thread limit in Windows 10 is 32, what’s the issue? What am I missing?

28 not 18 :slight_smile:

oops typo, 28 indeed, but I’m right that 28 CPU threads on a 32 thread default win10 system can be fully utilized without OS tinkering?