hi,

i’m running Debian 10 on POWER9 and would like to spawn x86_64 emulated VMs.

The virtual machine is configured to run with 8 vpus but it’s very slow.

On the host you can see that the qemu-system-x86_64 process is using just one core!

Ppc64le guests are using multi cores, so its looks like an config problem or software bug with the x86 emulator.

<domain type='qemu'>

<name>ubuntu</name>

<uuid>a38148e3-6a85-4793-8d58-8725e8bef25a</uuid>

<metadata>

<libosinfo:libosinfo xmlns:libosinfo="http://libosinfo.org/xmlns/libvirt/domain/1.0">

<libosinfo:os id="http://debian.org/debian/10"/>

</libosinfo:libosinfo>

</metadata>

<memory unit='KiB'>33554432</memory>

<currentMemory unit='KiB'>33554432</currentMemory>

<vcpu placement='static'>8</vcpu>

<os>

<type arch='x86_64' machine='pc-q35-5.0'>hvm</type>

<boot dev='hd'/>

</os>

<features>

<acpi/>

<apic/>

</features>

<cpu mode='custom' match='exact' check='none'>

<model fallback='forbid'>qemu64</model>

</cpu>

<clock offset='utc'>

<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>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'/>

<source file='/var/lib/libvirt/images/ubuntu-x86_64.qcow2'/>

<target dev='vda' bus='virtio'/>

<address type='pci' domain='0x0000' bus='0x04' slot='0x00' function='0x0'/>

</disk>

<disk type='file' device='cdrom'>

<driver name='qemu' type='raw'/>

<target dev='sda' bus='sata'/>

<readonly/>

<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='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='virtio-serial' index='0'>

<address type='pci' domain='0x0000' bus='0x03' slot='0x00' function='0x0'/>

</controller>

<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>

<interface type='bridge'>

<mac address='52:54:00:cc:08:18'/>

<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='tablet' bus='usb'>

<address type='usb' bus='0' port='1'/>

</input>

<input type='mouse' bus='ps2'/>

<input type='keyboard' bus='ps2'/>

<graphics type='vnc' port='-1' autoport='yes'>

<listen type='address'/>

</graphics>

<video>

<model type='qxl' ram='65536' vram='65536' vgamem='16384' heads='1' primary='yes'/>

<address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x0'/>

</video>

<memballoon model='virtio'>

<address type='pci' domain='0x0000' bus='0x05' slot='0x00' function='0x0'/>

</memballoon>

<rng model='virtio'>

<backend model='random'>/dev/urandom</backend>

<address type='pci' domain='0x0000' bus='0x06' slot='0x00' function='0x0'/>

</rng>

</devices>

</domain>

# ps ax|grep qemu

31546 ? Sl 2:38 /usr/bin/qemu-system-x86_64 -name guest=ubuntu,debug-threads=on -S -object secret,id=masterKey0,format=raw,file=/var/lib/libvirt/qemu/domain-59-ubuntu/master-key.aes -machine pc-q35-5.0,accel=tcg,usb=off,dump-guest-core=off -cpu qemu64 -m 32768 -overcommit mem-lock=off -smp 8,sockets=8,cores=1,threads=1 -uuid a38148e3-6a85-4793-8d58-8725e8bef25a -no-user-config -nodefaults -chardev socket,id=charmonitor,fd=32,server,nowait -mon chardev=charmonitor,id=monitor,mode=control -rtc base=utc,driftfix=slew -no-hpet -no-reboot -global ICH9-LPC.disable_s3=1 -global ICH9-LPC.disable_s4=1 -boot strict=on -device pcie-root-port,port=0x10,chassis=1,id=pci.1,bus=pcie.0,multifunction=on,addr=0x2 -device pcie-root-port,port=0x11,chassis=2,id=pci.2,bus=pcie.0,addr=0x2.0x1 -device pcie-root-port,port=0x12,chassis=3,id=pci.3,bus=pcie.0,addr=0x2.0x2 -device pcie-root-port,port=0x13,chassis=4,id=pci.4,bus=pcie.0,addr=0x2.0x3 -device pcie-root-port,port=0x14,chassis=5,id=pci.5,bus=pcie.0,addr=0x2.0x4 -device pcie-root-port,port=0x15,chassis=6,id=pci.6,bus=pcie.0,addr=0x2.0x5 -device pcie-root-port,port=0x16,chassis=7,id=pci.7,bus=pcie.0,addr=0x2.0x6 -device qemu-xhci,p2=15,p3=15,id=usb,bus=pci.2,addr=0x0 -device virtio-serial-pci,id=virtio-serial0,bus=pci.3,addr=0x0 -blockdev {"driver":"file","filename":"/var/lib/libvirt/images/ubuntu-x86_64.qcow2","node-name":"libvirt-2-storage","auto-read-only":true,"discard":"unmap"} -blockdev {"node-name":"libvirt-2-format","read-only":false,"driver":"qcow2","file":"libvirt-2-storage","backing":null} -device virtio-blk-pci,bus=pci.4,addr=0x0,drive=libvirt-2-format,id=virtio-disk0,bootindex=2 -blockdev {"driver":"file","filename":"/var/lib/libvirt/images/ubuntu-20.04-live-server-amd64.iso","node-name":"libvirt-1-storage","auto-read-only":true,"discard":"unmap"} -blockdev {"node-name":"libvirt-1-format","read-only":true,"driver":"raw","file":"libvirt-1-storage"} -device ide-cd,bus=ide.0,drive=libvirt-1-format,id=sata0-0-0,bootindex=1 -netdev tap,fd=34,id=hostnet0 -device virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:00:cc:08:18,bus=pci.1,addr=0x0 -chardev pty,id=charserial0 -device isa-serial,chardev=charserial0,id=serial0 -chardev socket,id=charchannel0,fd=35,server,nowait -device virtserialport,bus=virtio-serial0.0,nr=1,chardev=charchannel0,id=channel0,name=org.qemu.guest_agent.0 -device usb-tablet,id=input0,bus=usb.0,port=1 -vnc 127.0.0.1:1 -device qxl-vga,id=video0,ram_size=67108864,vram_size=67108864,vram64_size_mb=0,vgamem_mb=16,max_outputs=1,bus=pcie.0,addr=0x1 -device virtio-balloon-pci,id=balloon0,bus=pci.5,addr=0x0 -object rng-random,id=objrng0,filename=/dev/urandom -device virtio-rng-pci,rng=objrng0,id=rng0,bus=pci.6,addr=0x0 -sandbox on,obsolete=deny,elevateprivileges=deny,spawn=deny,resourcecontrol=deny -msg timestamp=on

Does anybody knows this problem?

Best regards

Kim