Windows Gaming VM on Proxmox: Performance Optimization in MSFS 2020

This is a shot in the blue. Maybe changing the platform (cpu make of the vm) is worth a shot (maybe to something generic like “sky lake”), I can imagine if a CPU feature is not working correctly you would experience something similar.

  • You don’t have ondemand as an option in the governor, you should use performance to get maximum performance for the tests
  • You’re missing one core in the taskset list, you only have 11, I think you should add core 4 as well …
    Also, depending on your CPU topology, it may be best to list them in thread pairs
  • the line
#assign_interrupts 5,6,7,8,9,10,11,12,13,14,15 0000%3A65%3A00.0

Sould be:

#assign_interrupts 5,6,7,8,9,10,11,12,13,14,15 0000:65:00.0
  • You are not passing through the audio device of the card, you probably should
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I ended up reinstalling msfs, which somehow fixed my stuttering issue, but now I have similar low framerates as PeterPorker3. Might have been due to a software update since the configuration was otherwise similar.

Ran through most of the suggestions in this thread, without much success. I think switching the CPU to Broadwell/Skylake gained a few fps, but without a consistent benchmark it’s hard to say. DX11 was another few fps faster than DX12, but at best I end up with ~25 fps in GA aircraft.

I used taskset to pin the 12 cores I have assigned to the VM and verified with /proc/cpuinfo that they’re boosting as expected (between 3800-4200MHz).

For reference here’s my .conf, the VM is running on a W-2140B and an RTX3070:

agent: 1
balloon: 0
bios: ovmf
boot: cd
bootdisk: sata0
cores: 12
cpu: Skylake-Client,flags=+pdpe1gb;+hv-tlbflush;+aes
efidisk0: local-lvm:vm-103-disk-0,size=4M
hostpci0: 0000:1a:00,pcie=1
machine: q35
memory: 16384
name: elitebook-windows11
net0: virtio=,bridge=vmbr0,rate=50
numa: 0
ostype: win11
sata0: local-lvm:vm-103-disk-1,cache=writeback,size=244200M
scsi1: nvme-data:103/vm-103-disk-0.raw,backup=0,cache=writeback,iothread=1,size=460G
scsihw: virtio-scsi-pci
smbios1: uuid=6b5ca66c-60d7-4e73-b9e8-39412d9c89de
sockets: 1
tablet: 0
tpmstate0: local-lvm:vm-103-disk-2,size=4M,version=v2.0
vga: none
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Tried disabling hyperthreading, which helped more than I expected and now I’m seeing ~35fps. The GPU and CPU loads are still low so I don’t think it’s solved the root issue, but at least now it’s playable.

So I tried @MadMatt and @Dratatoo most recent suggestions one by one, but unfortunately the only thing that made a difference was changing from ‘ondemand’ to ‘performance,’ but that was only 1-2fps more at the most. Now I have no errors left in the console while starting the VM.

I have not tried disabling hyperthreading since some other applications I run on this machine benefit from the additional threads.

My last idea: perhaps there is some sort of BIOS issue. I think it’s unlikely to be the cause, but I suppose it’s worth investigating. @GMntR what brand of machine are you using (I have a dell precision 5820, second to most recent BIOS)? My logic is if we are using two different manufacturers, yet experiencing the same issue, a BIOS issue can be ruled out. Unfortunately I cannot try updating the bios atm since it requires windows to be running on the bare metal.

But ultimately I am convinced there is an issue with the game engine and compatibility with KVM/qemu that cannot be solved through other means. Maybe it’s worth trying to get in touch with Asobo.

Support request has been created: https://flightsimulator.zendesk.com/hc/en-us/requests/168320

I have an Asus C422 WS Sage/10G motherboard. Latest BIOS, so I don’t think that’s the issue.

Yea, I would have to agree. Completely different brand of platform yet same issue…

Response from support. I guess this is not bad news, but I don’t expect it to be a high priority. May have to wait for the next big performance-focused update to see if anything changed.