Hi
I have a RX 6600 connected via 16 PCIe 4.0 lanes passed through to the Windows 10 guest but the performance is choppy on games that should run flawlessly at 1080p.
Anybody knows how to improve performance in a kvm / virtmanager vm?
I installed everything from the looking glass site.
Are there any optimizations?
I’ve had similar problems and dropped looking glass entirely. It’s not a perfect solution and the current, recommended release is pretty old. I think it’s just a looking glass problem.
Many, post your client and host logs, along with your full system specifications.
No it isn’t.
Very likely not, if you had asked for some assistance you would likey have had your issue solved.
I solved it by going to a discord channel / server.
The main problem was that I tried to do Hyper-V in the VM meaning nested virtualization and that is not supported the way I knew to do it.
I turned nested virtualization off and now I just have a bar running through my video output that I have to fix.
The network virtualization has to be tweaked too, still.
Here is the most important part of the code (I hope I remember correctly 
):
<feature policy="disable" name="svm"/>
This is the whole subsection (caution 16 threads adapt to your needs):
<cpu mode="host-passthrough" check="none" migratable="off">
<topology sockets="1" dies="1" cores="8" threads="2"/>
<cache mode="passthrough"/>
<feature policy="require" name="topoext"/>
<feature policy="disable" name="svm"/>
</cpu>
Here is the xml of the whole VM (needs to be tweaked for CPUs with less than 24-32 threads:
<domain type="kvm">
<name>win10</name>
<uuid>6b7d09af-bd11-4f0b-9914-002d898cf2e8</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">33554432</memory>
<currentMemory unit="KiB">33554432</currentMemory>
<vcpu placement="static">16</vcpu>
<cputune>
<vcpupin vcpu="0" cpuset="8"/>
<vcpupin vcpu="1" cpuset="24"/>
<vcpupin vcpu="2" cpuset="9"/>
<vcpupin vcpu="3" cpuset="25"/>
<vcpupin vcpu="4" cpuset="10"/>
<vcpupin vcpu="5" cpuset="26"/>
<vcpupin vcpu="6" cpuset="11"/>
<vcpupin vcpu="7" cpuset="27"/>
<vcpupin vcpu="8" cpuset="12"/>
<vcpupin vcpu="9" cpuset="28"/>
<vcpupin vcpu="10" cpuset="13"/>
<vcpupin vcpu="11" cpuset="29"/>
<vcpupin vcpu="12" cpuset="14"/>
<vcpupin vcpu="13" cpuset="30"/>
<vcpupin vcpu="14" cpuset="15"/>
<vcpupin vcpu="15" cpuset="31"/>
</cputune>
<os firmware="efi">
<type arch="x86_64" machine="pc-q35-5.2">hvm</type>
<loader secure="yes"/>
<bootmenu enable="yes"/>
</os>
<features>
<acpi/>
<apic/>
<hyperv mode="custom">
<relaxed state="on"/>
<vapic state="on"/>
<spinlocks state="on" retries="8191"/>
<vpindex state="on"/>
<synic state="on"/>
<stimer state="on"/>
<reset state="on"/>
</hyperv>
<vmport state="off"/>
</features>
<cpu mode="host-passthrough" check="none" migratable="off">
<topology sockets="1" dies="1" cores="8" threads="2"/>
<cache mode="passthrough"/>
<feature policy="require" name="topoext"/>
<feature policy="disable" name="svm"/>
</cpu>
<clock offset="localtime">
<timer name="rtc" tickpolicy="catchup"/>
<timer name="pit" tickpolicy="delay"/>
<timer name="hpet" present="no"/>
<timer name="hypervclock" present="yes"/>
</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="cdrom">
<driver name="qemu" type="raw"/>
<target dev="sda" bus="sata"/>
<readonly/>
<boot order="1"/>
<address type="drive" controller="0" bus="0" target="0" unit="0"/>
</disk>
<controller type="usb" index="0" model="qemu-xhci" ports="15">
<address type="pci" domain="0x0000" bus="0x01" 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-to-pci-bridge">
<model name="pcie-pci-bridge"/>
<address type="pci" domain="0x0000" bus="0x08" slot="0x00" function="0x0"/>
</controller>
<controller type="pci" index="10" model="pcie-root-port">
<model name="pcie-root-port"/>
<target chassis="10" port="0x18"/>
<address type="pci" domain="0x0000" bus="0x00" slot="0x03" function="0x0"/>
</controller>
<controller type="pci" index="11" model="pcie-root-port">
<model name="pcie-root-port"/>
<target chassis="11" port="0x8"/>
<address type="pci" domain="0x0000" bus="0x00" slot="0x01" function="0x0" multifunction="on"/>
</controller>
<controller type="pci" index="12" model="pcie-root-port">
<model name="pcie-root-port"/>
<target chassis="12" port="0x9"/>
<address type="pci" domain="0x0000" bus="0x00" slot="0x01" function="0x1"/>
</controller>
<controller type="virtio-serial" index="0">
<address type="pci" domain="0x0000" bus="0x02" slot="0x00" function="0x0"/>
</controller>
<controller type="fdc" index="0"/>
<interface type="user">
<mac address="52:54:00:ca:14:46"/>
<model type="e1000e"/>
<address type="pci" domain="0x0000" bus="0x07" 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="spicevmc">
<target type="virtio" name="com.redhat.spice.0"/>
<address type="virtio-serial" controller="0" bus="0" port="1"/>
</channel>
<input type="keyboard" bus="ps2"/>
<input type="mouse" bus="ps2"/>
<input type="mouse" bus="virtio">
<address type="pci" domain="0x0000" bus="0x03" slot="0x00" function="0x0"/>
</input>
<input type="keyboard" bus="virtio">
<address type="pci" domain="0x0000" bus="0x0a" slot="0x00" function="0x0"/>
</input>
<graphics type="spice" port="5800" autoport="no">
<listen type="address"/>
<image compression="off"/>
<gl enable="no"/>
</graphics>
<sound model="ich9">
<audio id="1"/>
<address type="pci" domain="0x0000" bus="0x00" slot="0x1b" function="0x0"/>
</sound>
<audio id="1" type="spice"/>
<video>
<model type="none"/>
</video>
<hostdev mode="subsystem" type="pci" managed="yes">
<source>
<address domain="0x0000" bus="0x01" slot="0x00" function="0x0"/>
</source>
<address type="pci" domain="0x0000" bus="0x0c" slot="0x00" function="0x0"/>
</hostdev>
<hostdev mode="subsystem" type="pci" managed="yes">
<source>
<address domain="0x0000" bus="0x2f" slot="0x00" function="0x0"/>
</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="0x2f" slot="0x00" function="0x1"/>
</source>
<address type="pci" domain="0x0000" bus="0x0b" slot="0x00" function="0x0"/>
</hostdev>
<redirdev bus="usb" type="spicevmc">
<address type="usb" bus="0" port="2"/>
</redirdev>
<redirdev bus="usb" type="spicevmc">
<address type="usb" bus="0" port="3"/>
</redirdev>
<memballoon model="none"/>
<shmem name="looking-glass">
<model type="ivshmem-plain"/>
<size unit="M">32</size>
<address type="pci" domain="0x0000" bus="0x09" slot="0x01" function="0x0"/>
</shmem>
<shmem name="scream-ivshmem">
<model type="ivshmem-plain"/>
<size unit="M">2</size>
<address type="pci" domain="0x0000" bus="0x09" slot="0x02" function="0x0"/>
</shmem>
</devices>
</domain>
By the way, thanks GNIF for LG.