High latency in "usbport.sys" in Windows 10 Guest

[El_Don]

Hi there,
I hope that you can help me with a problem, that drives me crazy for days.

I'd like to use a Windows 10 guest as a DAW (Digital Audio Workstation).
I have a USB Focusrite Solo 3rd Generation Soundcard. I passed through the USB controller (IOMMU) and everything seemed to work fine at first.
Except that I have very high latencies in the windows 'usbport.sys' driver every few seconds.

To examine the problem, I did a fresh Windows 10 installation "out of the box". Just updates, guest tools (last stable version) and nothing else.
Result: High latencies in usbport.sys every few seconds

My server is pretty up to date. There shouldn't be any performance problems.

CPU: Intel Core i5 Comet Lake
RAM: 64 GB
HDD: 8TB (1,5 TB SSD für das Proxmox OS und die VMs)
Proxmox: 6.4-6

For the Windows 10 VM I used:
CPU: 1 socket, 12 cores
RAM: 24 GB
BIOS: OVMF
Machine: pc-q35-5.2
VirtIO drivers, installed with "Windows 10 best practices"
https://pve.proxmox.com/wiki/Windows_10_guest_best_practices

My question: Is this problem known? Did I something wrong in the VM configuration?
I searched for every possible reason, but found nothing.

Thank you

 

[dcsapak]

can you post the full vm config? (qm config ID)
also try disabling the 'use tablet for pointer' under options

 

[El_Don]

This is the vm config:


acpi: 1
agent: 1
bios: ovmf
boot: order=scsi0;net0
cores: 12
efidisk0: local-lvm:vm-105-disk-1,size=4M
machine: pc-q35-5.2
memory: 24000
name: Win10-NewMusic
net0: virtio=BE:47:02:0A:70:55,bridge=vmbr0
numa: 0
ostype: win10
scsi0: local-lvm:vm-105-disk-0,cache=unsafe,discard=on,size=32G
scsihw: virtio-scsi-pci
smbios1: uuid=4909a50a-7bef-4300-b859-75b16e3e025e
sockets: 1
tablet: 1
vmgenid: 062dfa58-bbb8-46fc-97d7-688e356394c5

Thanks for your help!

 

[dcsapak]

did you try to disable the tablet pointer? and did it help?

 

[El_Don]

Oh sorry for the missing answer (and the double post ;-) ).
I did a 10 minute stress test with LatencyMon (over Remote Desktop Protocol with 'tablet pointor switched off) and results are not perfect, but improved. Maybe I can tweak some windows features to get even better results.
One idea was to delete the spice drivers, because i don't need them anyway.

So this was, as I said, Windows 10 'out of the box'.
I just ordered a PCIe USB3 card, because in my IOMMU group was another group member named "RAM MEMORY".

IOMMU Group 4 00:14.0 USB controller [0c03]: Intel Corporation Device [8086:06ed] IOMMU Group 4 00:14.2 RAM memory [0500]: Intel Corporation Device [8086:06ef]

I assume that this was another cause why I had so much latency an so many page faults.
But, as I said, without IOMMU I had the same problems with fewer page faults.
Strange.... anyway... I'll do some tests later and if there are more problems, I'll be back ;-)

 

[El_Don]

Damn... Back from the office I wanted to do a final test and... bam!...here we go again :-(
Latency up to 3ms. This is far too much for an DAW. This is so frustrating :-(
Any ideas?

 

[El_Don]

Well I'm going to answer it for myself (I nearly did it in my post above).
It was my mistake, because, as you see, I have an IOMMU Group with the USB Controller and the RAM memory.
I accidentally passed the whole IOMMU group through, so that the interrupt control was not visible for the server anymore.
That was leading to errors in the sound beacuse of the faulty interrupt control.
The clue is: Once attached to a VM, the error existed in other VMs. I first had to

echo 0000:00:14.0 > /sys/bus/pci/devices/0000\:00\:14.0/driver/unbind
and then
echo 0000:00:14.0 > /sys/bus/pci/drivers/xhci_hcd/bind

My problem should (hopefully) be solved with the extra USB controller.
But maybe I have a basic misunterstanding with IOMMU and ACS. But for this I will open a separate thread in the german forum.

 

[eminempt]

Hi. how you doing? did this two last steps solved your problem? couldn't get it.
im also having this latency

what will this two steps do, exactly? can you elaborate a bit more?


Thanks,