7950X3D + Proxmox CPU Core Pinning = ???

[Pragma808]

Hello!

I have been anticipating the Ryzen 7000 series 3D V-Cache chips for some time now and am planning to build a new system with one soon. If the situation I detail below performs as I hope, I would like to use it in a Proxmox system with a Windows gaming VM.

Now that the 7950X3D & 7900X3D are out, we know that only 1 CCD has access to the large cache and the Windows Game Bar mechanism to park the cores on the non-V-Cache CCD is being used. Also, on the Proxmox side of things, as of release 7.3, it is possible to pin CPU cores to a VM.

Given that info, the question in my mind is…

Would a gaming VM that has had only the cores from the V-Cache CCD pinned to it perform similarly to a native Windows system on the same hardware?​

Also, is there any obvious reason this wouldn’t work?

While not exactly the same, the core pinning in Proxmox seems like it could kind-of-sort-of accomplish the same as the core parking in Windows, but I am not well versed enough in the nuts and bolts CPU pinning/parking/affinity/etc to make an educated guess.

If I had an AM5 system now, I would absolutely test this out. I am curious if anyone on here shares my curiosity has the ability to test this.

NOTE: I also posted this over on the Level1Techs forum: 7950X3D + Proxmox CPU Core Pinning = Gaming VM w/ V-Cache?

 

[Kenzi]

Apart from normal virtualisation overhead, if you just allocate 3d cores then it will perform like a 7800x3d or thereabouts. I am setting up a server on a 7950x3d today, I could benchmark some things if you wanted.

 

[Pragma808]

Apart from normal virtualisation overhead, if you just allocate 3d cores then it will perform like a 7800x3d or thereabouts. I am setting up a server on a 7950x3d today, I could benchmark some things if you wanted.

That would be awesome! I would definitely appreciate that info.

 

[Pragma808]

Apart from normal virtualisation overhead, if you just allocate 3d cores then it will perform like a 7800x3d or thereabouts. I am setting up a server on a 7950x3d today, I could benchmark some things if you wanted.

One of my concerns with the 7950X3D under virtualization is how the system would handle the 7950X3D/7900X3D's core parking mechanic. Basically, will Windows still attempt to park cores?

In one of the 7800X3D reviews (I think GN), it was pointed out that systems previously used with the 7950X3D would need a fresh Windows install because it would still attempt to park cores (parkour!) despite this mechanism not being needed on the 7800X3D. I am curious as to what exactly happens to a 7950X3D VM with half the core count.

In your testing, I'd keep an eye on CPU utilization to see if anything is awry. Looking forward to your findings. Cheers and thank you!

 

[Kenzi]

Hey, sorry for my late reply, kind of forgot about this.
I have a windows VM on half the cores, seems to work pretty well running a DCS server. I have other vms running on the other cores so nothing is really getting parked since they are all loaded. Keeping workloads separate looks like it keeps performance high - mixing and matching cores has a slight detriment to CPU benchmarks, however, it's not that much. I haven't tried giving a windows VM all the cores yet and seeing how it balances things across cores, and I don't think I have anything I could run to test that very well.

 

[abdullah.k]

Hello people
I have 7900x3d running gaming windows vm and allocated 0-5,12-17 cpus for that vm but the cache reported by windows is not correct
is that normal ? should be there any flag for cpu to report the correct cache ?