Poor FPS/Performance in Windows 10 Guest

Hey there,

I’m having one hell of a time with my Windows 10 VM. Here’s my predicament - I recently bought an ROG Zephyrus G15. Specs are a Ryzen 7 4800HS, 16GB RAM, and a GTX 1660Ti. I’m using the iGPU for my host and passing through the 1660Ti, using a dummy display and Looking Glass to view it. Arch is the host OS.

The intention of the VM is exclusively to play EAC games such as Fortnite and Hunt: Showdown which can’t be run on Linux. Typical operation is indistinguisable, but I am having noticeable issues when firing up a game.

For example, using CS:GO as a main benchmark, I average about 170-180 FPS running baremetal on Linux. On Windows baremetal, it’s about the same (within 10 FPS). However, on the VM, I’m getting about 50-60. Another is example is League of Legends. Using Wine in Linux, I average around 140 FPS, with 10-20 FPS difference on baremetal Windows. On the VM, I get around 60FPS, sometimes peaking to 70. As I know Fortnite is a pretty demanding game for the hardware I’m using, I haven’t yet installed it on the VM.

Now I know Looking Glass and using a VM to game isn’t perfect, and I should expect some performance loss, but I feel like getting an FPS loss of over 50% isn’t normal.

I have tried with and without hugepages, and have tried using 12 vcpus, and then also tried only 8, as I read somewhere that only running the VM on cores which are all on the same CCX might help. I really think this is some weird CPU or Ryzen-specific issue, but I’m open to any suggestions or tweaks that you think might help.

Here’s my libvirt XML as well. If there’s any other important info I failed to mention please just let me know and I’ll provide it! :slight_smile:

<domain xmlns:qemu="http://libvirt.org/schemas/domain/qemu/1.0" type="kvm">
  <name>win10</name>
  <uuid>f8804fe6-222e-4f27-93da-ed0674bd86f3</uuid>
  <metadata>
    <libosinfo:libosinfo xmlns:libosinfo="http://libosinfo.org/xmlns/libvirt/domain/1.0">
      <libosinfo:os id="http://microsoft.com/win/10"/>
    </libosinfo:libosinfo>
  </metadata>
  <memory unit="KiB">8388608</memory>
  <currentMemory unit="KiB">8388608</currentMemory>
  <vcpu placement="static" cpuset="8-15">8</vcpu>
  <iothreads>1</iothreads>
  <cputune>
    <vcpupin vcpu="0" cpuset="8"/>
    <vcpupin vcpu="1" cpuset="9"/>
    <vcpupin vcpu="2" cpuset="10"/>
    <vcpupin vcpu="3" cpuset="11"/>
    <vcpupin vcpu="4" cpuset="12"/>
    <vcpupin vcpu="5" cpuset="13"/>
    <vcpupin vcpu="6" cpuset="14"/>
    <vcpupin vcpu="7" cpuset="15"/>
    <emulatorpin cpuset="0-3"/>
    <iothreadpin iothread="1" cpuset="4-7"/>
  </cputune>
  <os>
    <type arch="x86_64" machine="pc-q35-5.2">hvm</type>
    <loader readonly="yes" type="pflash">/usr/share/edk2-ovmf/x64/OVMF_CODE.fd</loader>
    <nvram>/var/lib/libvirt/qemu/nvram/win10_VARS.fd</nvram>
    <boot dev="hd"/>
    <bootmenu enable="no"/>
  </os>
  <features>
    <acpi/>
    <apic/>
    <hyperv>
      <relaxed state="on"/>
      <vapic state="on"/>
      <spinlocks state="on" retries="8191"/>
      <vpindex state="on"/>
      <runtime state="on"/>
      <synic state="on"/>
      <stimer state="on"/>
      <reset state="on"/>
      <vendor_id state="on" value="GAMINGVM"/>
      <frequencies state="on"/>
    </hyperv>
    <kvm>
      <hidden state="on"/>
    </kvm>
    <vmport state="off"/>
  </features>
  <cpu mode="host-passthrough" check="none" migratable="off">
    <topology sockets="1" dies="1" cores="4" threads="2"/>
    <cache mode="passthrough"/>
    <feature policy="require" name="topoext"/>
    <feature policy="require" name="svm"/>
    <feature policy="require" name="apic"/>
    <feature policy="require" name="hypervisor"/>
    <feature policy="require" name="invtsc"/>
    <feature policy="disable" name="amd-stibp"/>
  </cpu>
  <clock offset="localtime">
    <timer name="rtc" tickpolicy="catchup"/>
    <timer name="pit" tickpolicy="delay"/>
    <timer name="hpet" present="no"/>
    <timer name="kvmclock" present="no"/>
    <timer name="hypervclock" present="yes"/>
    <timer name="tsc" present="yes" mode="native"/>
  </clock>
  <on_poweroff>destroy</on_poweroff>
  <on_reboot>restart</on_reboot>
  <on_crash>destroy</on_crash>
  <pm>
    <suspend-to-mem enabled="no"/>
    <suspend-to-disk enabled="no"/>
  </pm>
  <devices>
    <emulator>/usr/bin/qemu-system-x86_64</emulator>
    <disk type="file" device="disk">
      <driver name="qemu" type="qcow2" cache="writeback" discard="unmap"/>
      <source file="/var/lib/libvirt/images/win10.qcow2"/>
      <target dev="vda" bus="virtio"/>
      <address type="pci" domain="0x0000" bus="0x03" slot="0x00" function="0x0"/>
    </disk>
    <controller type="usb" index="0" model="qemu-xhci" ports="15">
      <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="pci" index="0" model="pcie-root"/>
    <controller type="pci" index="1" model="pcie-root-port">
      <model name="pcie-root-port"/>
      <target chassis="1" port="0x10"/>
      <address type="pci" domain="0x0000" bus="0x00" slot="0x02" function="0x0" multifunction="on"/>
    </controller>
    <controller type="pci" index="2" model="pcie-root-port">
      <model name="pcie-root-port"/>
      <target chassis="2" port="0x11"/>
      <address type="pci" domain="0x0000" bus="0x00" slot="0x02" function="0x1"/>
    </controller>
    <controller type="pci" index="3" model="pcie-root-port">
      <model name="pcie-root-port"/>
      <target chassis="3" port="0x12"/>
      <address type="pci" domain="0x0000" bus="0x00" slot="0x02" function="0x2"/>
    </controller>
    <controller type="pci" index="4" model="pcie-root-port">
      <model name="pcie-root-port"/>
      <target chassis="4" port="0x13"/>
      <address type="pci" domain="0x0000" bus="0x00" slot="0x02" function="0x3"/>
    </controller>
    <controller type="pci" index="5" model="pcie-root-port">
      <model name="pcie-root-port"/>
      <target chassis="5" port="0x14"/>
      <address type="pci" domain="0x0000" bus="0x00" slot="0x02" function="0x4"/>
    </controller>
    <controller type="pci" index="6" model="pcie-root-port">
      <model name="pcie-root-port"/>
      <target chassis="6" port="0x15"/>
      <address type="pci" domain="0x0000" bus="0x00" slot="0x02" function="0x5"/>
    </controller>
    <controller type="pci" index="7" model="pcie-root-port">
      <model name="pcie-root-port"/>
      <target chassis="7" port="0x16"/>
      <address type="pci" domain="0x0000" bus="0x00" slot="0x02" function="0x6"/>
    </controller>
    <controller type="pci" index="8" model="pcie-root-port">
      <model name="pcie-root-port"/>
      <target chassis="8" port="0x17"/>
      <address type="pci" domain="0x0000" bus="0x00" slot="0x02" function="0x7"/>
    </controller>
    <controller type="pci" index="9" model="pcie-root-port">
      <model name="pcie-root-port"/>
      <target chassis="9" port="0x18"/>
      <address type="pci" domain="0x0000" bus="0x00" slot="0x03" function="0x0" multifunction="on"/>
    </controller>
    <controller type="pci" index="10" model="pcie-to-pci-bridge">
      <model name="pcie-pci-bridge"/>
      <address type="pci" domain="0x0000" bus="0x09" slot="0x00" function="0x0"/>
    </controller>
    <controller type="pci" index="11" model="pcie-root-port">
      <model name="pcie-root-port"/>
      <target chassis="11" port="0x19"/>
      <address type="pci" domain="0x0000" bus="0x00" slot="0x03" function="0x1"/>
    </controller>
    <controller type="pci" index="12" model="pcie-root-port">
      <model name="pcie-root-port"/>
      <target chassis="12" port="0x1a"/>
      <address type="pci" domain="0x0000" bus="0x00" slot="0x03" function="0x2"/>
    </controller>
    <interface type="network">
      <mac address="52:54:00:fa:e3:93"/>
      <source network="default"/>
      <model type="virtio"/>
      <address type="pci" domain="0x0000" bus="0x01" slot="0x00" function="0x0"/>
    </interface>
    <input type="mouse" bus="ps2"/>
    <input type="keyboard" bus="ps2"/>
    <hostdev mode="subsystem" type="pci" managed="yes">
      <source>
        <address domain="0x0000" bus="0x01" slot="0x00" function="0x0"/>
      </source>
      <address type="pci" domain="0x0000" bus="0x05" slot="0x00" function="0x0"/>
    </hostdev>
    <hostdev mode="subsystem" type="pci" managed="yes">
      <source>
        <address domain="0x0000" bus="0x01" slot="0x00" function="0x1"/>
      </source>
      <address type="pci" domain="0x0000" bus="0x06" slot="0x00" function="0x0"/>
    </hostdev>
    <hostdev mode="subsystem" type="pci" managed="yes">
      <source>
        <address domain="0x0000" bus="0x01" slot="0x00" function="0x2"/>
      </source>
      <address type="pci" domain="0x0000" bus="0x07" slot="0x00" function="0x0"/>
    </hostdev>
    <hostdev mode="subsystem" type="pci" managed="yes">
      <source>
        <address domain="0x0000" bus="0x01" slot="0x00" function="0x3"/>
      </source>
      <address type="pci" domain="0x0000" bus="0x08" slot="0x00" function="0x0"/>
    </hostdev>
    <memballoon model="virtio">
      <address type="pci" domain="0x0000" bus="0x04" slot="0x00" function="0x0"/>
    </memballoon>
    <shmem name="looking-glass">
      <model type="ivshmem-plain"/>
      <size unit="M">32</size>
      <address type="pci" domain="0x0000" bus="0x0a" slot="0x01" function="0x0"/>
    </shmem>
  </devices>
  <qemu:commandline>
    <qemu:arg value="-acpitable"/>
    <qemu:arg value="file=/home/kyle/VFIO/acpitable.bin"/>
  </qemu:commandline>
</domain>

Hi there, did you ever figure out the low FPS issue in Win VM for gaming that you wrote about in this post? Were you able to get it up to the 100+ FPS range like you saw on baremetal Linux and Windows?

Just because i saw 60 and CSGO,
do you have Vsync on in CSGO? i think is on by default… maybe while troubleshooting you forgot about it.

I always like to remember about Vsync because i had my fair share of times not remembering to disable it, outside of that i legit have no clue :stuck_out_tongue: