Network transfer causing high CPU load and stuttering on VM

[DuckBrained]

Hi all

 

I’ve been working on this for two days now and I’m running out of ideas. 

 

In summary, when I use my Windows 10 VM to copy files from an SMB share on a separate NAS, I’m seeing stuttering on the VM (mouse sticking/jumping etc) and on the UnRAID main screen, I see a single CPU core running at 100%.

 

I have a 10Gbe network connection on the UnRAID host to a switch which by all accounts is working well - the transfer rates are as expected. But the VM stuttering is problematic.

 

The network adapter is: Aquantia Corp. AQC107 NBase-T/IEEE 802.3bz Ethernet Controller

 

Here’s what I’ve tried so far:

 

New VM from scratch - same result

Using TeraCopy - actually less stuttering but half the transfer speed

Trying vmxnet3 driver instead - same result - stuttering

Tips and Tweaks - Disable flow control (no change)

Tips and Tweaks - Disable NIC offload (no change)

New VM without Passthrough - a little better, but still seeing the CPU spike

Adding more cores - but does nothing as this seems to be a single thread process

 

I’m at a loss. If it helps here’s the VM XML but I’ve tried all kinds of combos here to no avail:

 

<?xml version='1.0' encoding='UTF-8'?>
<domain type='kvm'>
  <name>Windows 10 Test Passthrough</name>
  <uuid>6df512b5-c2c5-d74f-2781-1ec861d63c30</uuid>
  <metadata>
    <vmtemplate xmlns="unraid" name="Windows 10" icon="windows.png" os="windows10"/>
  </metadata>
  <memory unit='KiB'>16777216</memory>
  <currentMemory unit='KiB'>16777216</currentMemory>
  <memoryBacking>
    <nosharepages/>
  </memoryBacking>
  <vcpu placement='static'>8</vcpu>
  <cputune>
    <vcpupin vcpu='0' cpuset='6'/>
    <vcpupin vcpu='1' cpuset='22'/>
    <vcpupin vcpu='2' cpuset='7'/>
    <vcpupin vcpu='3' cpuset='23'/>
    <vcpupin vcpu='4' cpuset='8'/>
    <vcpupin vcpu='5' cpuset='24'/>
    <vcpupin vcpu='6' cpuset='9'/>
    <vcpupin vcpu='7' cpuset='25'/>
  </cputune>
  <os>
    <type arch='x86_64' machine='pc-q35-4.2'>hvm</type>
    <loader readonly='yes' type='pflash'>/usr/share/qemu/ovmf-x64/OVMF_CODE-pure-efi.fd</loader>
    <nvram>/etc/libvirt/qemu/nvram/6df512b5-c2c5-d74f-2781-1ec861d63c30_VARS-pure-efi.fd</nvram>
  </os>
  <features>
    <acpi/>
    <apic/>
  </features>
  <cpu mode='host-passthrough' check='none'>
    <topology sockets='1' cores='4' threads='2'/>
    <cache mode='passthrough'/>
    <feature policy='require' name='topoext'/>
  </cpu>
  <clock offset='localtime'>
    <timer name='rtc' tickpolicy='catchup'/>
    <timer name='pit' tickpolicy='delay'/>
    <timer name='hpet' present='no'/>
  </clock>
  <on_poweroff>destroy</on_poweroff>
  <on_reboot>restart</on_reboot>
  <on_crash>restart</on_crash>
  <devices>
    <emulator>/usr/local/sbin/qemu</emulator>
    <disk type='file' device='disk'>
      <driver name='qemu' type='raw' cache='writeback'/>
      <source file='/mnt/disks/Samsung_SSD_970_EVO_Plus_1TB_S4EWNJ0N241749T/Windows 10 Test Passthrough/vdisk1.img'/>
      <target dev='hdc' bus='virtio'/>
      <boot order='1'/>
      <address type='pci' domain='0x0000' bus='0x03' slot='0x00' function='0x0'/>
    </disk>
    <disk type='file' device='cdrom'>
      <driver name='qemu' type='raw'/>
      <source file='/mnt/user/isos/Win10-TBX.iso'/>
      <target dev='hda' bus='sata'/>
      <readonly/>
      <boot order='2'/>
      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
    </disk>
    <disk type='file' device='cdrom'>
      <driver name='qemu' type='raw'/>
      <source file='/mnt/user/isos/VMware-tools-windows-11.0.5-15389592.iso'/>
      <target dev='hdb' bus='sata'/>
      <readonly/>
      <address type='drive' controller='0' bus='0' target='0' unit='1'/>
    </disk>
    <controller type='pci' index='0' model='pcie-root'/>
    <controller type='pci' index='1' model='pcie-root-port'>
      <model name='pcie-root-port'/>
      <target chassis='1' port='0x8'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x0' multifunction='on'/>
    </controller>
    <controller type='pci' index='2' model='pcie-root-port'>
      <model name='pcie-root-port'/>
      <target chassis='2' port='0x9'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1'/>
    </controller>
    <controller type='pci' index='3' model='pcie-root-port'>
      <model name='pcie-root-port'/>
      <target chassis='3' port='0xa'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x2'/>
    </controller>
    <controller type='pci' index='4' model='pcie-root-port'>
      <model name='pcie-root-port'/>
      <target chassis='4' port='0xb'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x3'/>
    </controller>
    <controller type='pci' index='5' model='pcie-root-port'>
      <model name='pcie-root-port'/>
      <target chassis='5' port='0xc'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x4'/>
    </controller>
    <controller type='pci' index='6' model='pcie-root-port'>
      <model name='pcie-root-port'/>
      <target chassis='6' port='0xd'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x5'/>
    </controller>
    <controller type='pci' index='7' model='pcie-root-port'>
      <model name='pcie-root-port'/>
      <target chassis='7' port='0xe'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x6'/>
    </controller>
    <controller type='virtio-serial' index='0'>
      <address type='pci' domain='0x0000' bus='0x02' slot='0x00' function='0x0'/>
    </controller>
    <controller type='sata' index='0'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x1f' function='0x2'/>
    </controller>
    <controller type='usb' index='0' model='ich9-ehci1'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x07' function='0x7'/>
    </controller>
    <controller type='usb' index='0' model='ich9-uhci1'>
      <master startport='0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x07' function='0x0' multifunction='on'/>
    </controller>
    <controller type='usb' index='0' model='ich9-uhci2'>
      <master startport='2'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x07' function='0x1'/>
    </controller>
    <controller type='usb' index='0' model='ich9-uhci3'>
      <master startport='4'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x07' function='0x2'/>
    </controller>
    <interface type='bridge'>
      <mac address='52:54:00:d6:75:8c'/>
      <source bridge='br0'/>
      <model type='virtio'/>
      <address type='pci' domain='0x0000' bus='0x01' slot='0x00' function='0x0'/>
    </interface>
    <serial type='pty'>
      <target type='isa-serial' port='0'>
        <model name='isa-serial'/>
      </target>
    </serial>
    <console type='pty'>
      <target type='serial' port='0'/>
    </console>
    <channel type='unix'>
      <target type='virtio' name='org.qemu.guest_agent.0'/>
      <address type='virtio-serial' controller='0' bus='0' port='1'/>
    </channel>
    <input type='mouse' bus='ps2'/>
    <input type='keyboard' bus='ps2'/>
    <hostdev mode='subsystem' type='pci' managed='yes'>
      <driver name='vfio'/>
      <source>
        <address domain='0x0000' bus='0x30' slot='0x00' function='0x0'/>
      </source>
      <rom file='/mnt/user/isos/Sapphire.RX570.4096.170323.rom'/>
      <address type='pci' domain='0x0000' bus='0x04' slot='0x00' function='0x0'/>
    </hostdev>
    <hostdev mode='subsystem' type='pci' managed='yes'>
      <driver name='vfio'/>
      <source>
        <address domain='0x0000' bus='0x30' slot='0x00' function='0x1'/>
      </source>
      <address type='pci' domain='0x0000' bus='0x05' slot='0x00' function='0x0'/>
    </hostdev>
    <hostdev mode='subsystem' type='pci' managed='yes'>
      <driver name='vfio'/>
      <source>
        <address domain='0x0000' bus='0x2e' slot='0x00' function='0x1'/>
      </source>
      <address type='pci' domain='0x0000' bus='0x06' slot='0x00' function='0x0'/>
    </hostdev>
    <hostdev mode='subsystem' type='usb' managed='no'>
      <source>
        <vendor id='0x1462'/>
        <product id='0x7c36'/>
      </source>
      <address type='usb' bus='0' port='1'/>
    </hostdev>
    <hostdev mode='subsystem' type='usb' managed='no'>
      <source>
        <vendor id='0x1b1c'/>
        <product id='0x0c0b'/>
      </source>
      <address type='usb' bus='0' port='2'/>
    </hostdev>
    <hostdev mode='subsystem' type='usb' managed='no'>
      <source>
        <vendor id='0x1b1c'/>
        <product id='0x0c19'/>
      </source>
      <address type='usb' bus='0' port='3'/>
    </hostdev>
    <memballoon model='none'/>
  </devices>
</domain>

 

Thanks in advance for any pointers.

Edited May 23, 2020 by DuckBrained
Added info about network card

[DuckBrained]

Some further testing.

 

Swap the primary network port for UnRAID to the Intel Gbe interface. The problem in the VM goes away.

 

Pass through the ACQ107 adapter through to the VM - works fine - no stuttering.

 

Pass through the Intel adapter through to the VM - works fine - no stuttering.

 

So, this looks like an ACQ107 / Kernel driver type thing. Some kind of issue at that level. Any ideas anyone? Or can anyone recommend a 10Gbe network card known to work? 

[DuckBrained]

Further update: upgraded to “next” branch of UnRAID. Problem is actually worse - now two cores on max with stuttering still

[DuckBrained]

In case anyone stumbles across this thread here's what I ended up doing.

 

I have two NICs, one 1Gbe and one 10Gbe

The 10Gbe is linked to the br0 bridge and routing table ensures this is the primary NIC/Bridge

1Gbe NIC linked to br1 bridge which is assigned to the Windows VM

To ensure fast transfer between UnRAID and the VM I also added virbr0 to the Win VM. I now can transfer across the network from SMB shares on my Synology without the CPU issue but keep the fast transfer with UnRAID shares (otherwise I'd be going back out to the network and only getting 1Gbps speeds).