Hi, I cannot add iothreads (https://libvirt.org/formatdomain.html#elementsIOThreadsAllocation) in the libvirt xml configuration file. Once I add "<iothreads>4</iothreads>" and other related config for IOthreads into the libvirt xml configuration file with virsh command and save it, these iothreads related configuration will disappear after I open libvirt xml configuration file again for double-check. The current libvirt xml configuration file is like following. # virsh dumpxml kvm1 <domain type='kvm'> <name>kvm1</name> <uuid>20811918-9057-4496-aa03-0fe9d1bcaf78</uuid> <memory unit='KiB'>8194304</memory> <currentMemory unit='KiB'>8194304</currentMemory> <vcpu placement='static'>6</vcpu> <cputune> <vcpupin vcpu='0' cpuset='0'/> <vcpupin vcpu='1' cpuset='1'/> <vcpupin vcpu='2' cpuset='2'/> <vcpupin vcpu='3' cpuset='3'/> <vcpupin vcpu='4' cpuset='4'/> <vcpupin vcpu='5' cpuset='5'/> <emulatorpin cpuset='12-15'/> </cputune> <resource> <partition>/machine</partition> </resource> <os> <type arch='x86_64' machine='pc-i440fx-2.0'>hvm</type> <boot dev='hd'/> </os> <features> <acpi/> <apic/> <pae/> </features> <clock offset='utc'/> <on_poweroff>destroy</on_poweroff> <on_reboot>restart</on_reboot> <on_crash>restart</on_crash> <devices> <emulator>/usr/bin/kvm-spice</emulator> <disk type='file' device='disk'> <driver name='qemu' type='raw' cache='none' io='native'/> <source file='/var/lib/libvirt/images/kvm1.img'/> <target dev='vda' bus='virtio'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/> </disk> <disk type='block' device='cdrom'> <driver name='qemu' type='raw'/> <target dev='hdc' bus='ide'/> <readonly/> <address type='drive' controller='0' bus='1' target='0' unit='0'/> </disk> <controller type='usb' index='0'> <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x2'/> </controller> <controller type='pci' index='0' model='pci-root'/> <controller type='scsi' index='0'> <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/> </controller> <controller type='ide' index='0'> <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1'/> </controller> <interface type='network'> <mac address='52:54:00:a7:67:eb'/> <source network='default'/> <model type='virtio'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/> </interface> <serial type='pty'> <target port='0'/> </serial> <console type='pty'> <target type='serial' port='0'/> </console> <input type='mouse' bus='ps2'/> <input type='keyboard' bus='ps2'/> <graphics type='vnc' port='-1' autoport='yes' listen='127.0.0.1'> <listen type='address' address='127.0.0.1'/> </graphics> <video> <model type='cirrus' vram='9216' heads='1'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/> </video> <memballoon model='virtio'> <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/> </memballoon> </devices> <seclabel type='none'/> </domain> I want to config above xml file to be like following but once I save it, the iothreads related configuration will disappear (like above) after I re-open the libvirt xml for double-check. <domain type='kvm' id='1' xmlns:qemu='http://libvirt.org/schemas/domain/qemu/1.0'> <name>kvm1</name> <memory unit='KiB'>8194304</memory> <currentMemory unit='KiB'>8194304</currentMemory> <vcpu placement='static'>6</vcpu> <iothreads>4</iothreads> <iothreadids> <iothread id="2"/> <iothread id="4"/> <iothread id="6"/> <iothread id="8"/> </iothreadids> <cputune> <vcpupin vcpu='0' cpuset='0'/> <vcpupin vcpu='1' cpuset='1'/> <vcpupin vcpu='2' cpuset='2'/> <vcpupin vcpu='3' cpuset='3'/> <vcpupin vcpu='4' cpuset='4'/> <vcpupin vcpu='5' cpuset='5'/> <emulatorpin cpuset="12-15"/> <iothreadpin iothread="2" cpuset="7"/> <iothreadpin iothread="4" cpuset="8"/> <iothreadpin iothread="6" cpuset="9"/> <iothreadpin iothread="8" cpuset="10"/> </cputune> <resource> <partition>/machine</partition> </resource> <os> <type arch='x86_64' machine='pc-i440fx-2.0'>hvm</type> <boot dev='hd'/> </os> <features> <acpi/> <apic/> <pae/> </features> <clock offset='utc'/> <on_poweroff>destroy</on_poweroff> <on_reboot>restart</on_reboot> <on_crash>restart</on_crash> <devices> <emulator>/usr/bin/kvm-spice</emulator> <disk type='file' device='disk'> <driver name='qemu' type='raw' cache='none' io='native' iothread='2-8'/> <source file='/home/wj47/ssd1/kvm1.img'/> <target dev='vda' bus='virtio'/> <alias name='virtio-disk0'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/> </disk> <disk type='block' device='cdrom'> <driver name='qemu' type='raw'/> <target dev='hdc' bus='ide'/> <readonly/> <alias name='ide0-1-0'/> <address type='drive' controller='0' bus='1' target='0' unit='0'/> </disk> <controller type='usb' index='0'> <alias name='usb0'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x2'/> </controller> <controller type='pci' index='0' model='pci-root'> <alias name='pci.0'/> </controller> <controller type='scsi' index='0'> <alias name='scsi0'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/> </controller> <controller type='ide' index='0'> <alias name='ide0'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1'/> </controller> <interface type='network'> <source network='default'/> <target dev='vnet0'/> <model type='virtio'/> <alias name='net0'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/> </interface> <serial type='pty'> <source path='/dev/pts/11'/> <target port='0'/> <alias name='serial0'/> </serial> <console type='pty' tty='/dev/pts/11'> <source path='/dev/pts/11'/> <target type='serial' port='0'/> <alias name='serial0'/> </console> <input type='mouse' bus='ps2'/> <input type='keyboard' bus='ps2'/> <graphics type='vnc' port='5900' autoport='yes' listen='127.0.0.1'> <listen type='address' address='127.0.0.1'/> </graphics> <video> <model type='cirrus' vram='9216' heads='1'/> <alias name='video0'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/> </video> <memballoon model='virtio'> <alias name='balloon0'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/> </memballoon> </devices> <seclabel type='none'/> </domain> Another concern is like this: can I config 4 dedicated IOthreads for one drive. Just like above, I want to start 4 IOthreads for virtio-disk0. If true, is my config like above correct? Thank you. Best, Weiwei Jia

On Wed, Dec 21, 2016 at 12:11:51PM -0500, Weiwei Jia wrote: > Hi, > > I cannot add iothreads > (https://libvirt.org/formatdomain.html#elementsIOThreadsAllocation) in > the libvirt xml configuration file. Once I add > "<iothreads>4</iothreads>" and other related config for IOthreads into > the libvirt xml configuration file with virsh command and save it, > these iothreads related configuration will disappear after I open > libvirt xml configuration file again for double-check. If XML disappears after saving it, this usually indicates that either you made a mistake and used the wrong XML element or in the wrong place, or that your libvirt version is too old to support it. You can use the virt-xml-validate too to verify your XML file against the schema for your installed version of libvirt, which will report any errrors.

On 12/21/2016 12:11 PM, Weiwei Jia wrote: > Hi, > > I cannot add iothreads > (https://libvirt.org/formatdomain.html#elementsIOThreadsAllocation) in > the libvirt xml configuration file. Once I add > "<iothreads>4</iothreads>" and other related config for IOthreads into > the libvirt xml configuration file with virsh command and save it, > these iothreads related configuration will disappear after I open > libvirt xml configuration file again for double-check. > > The current libvirt xml configuration file is like following. > If I try to just cut-n-paste the following xml into a buffer, then run virsh define kvm1.xml, I get: error: Failed to define domain from kvm1.xml error: Cannot check QEMU binary /usr/bin/kvm-spice: No such file or directory In order to support iothreads, it requires an "-object iothread"... The "shortest" command line using qemu-kvm would be "qemu-kvm -object iothread,id=xxx1", so you could try the same with that /usr/bin/kvm-spice image and see what you get. You could try to figure out from the /var/cach/libvirt/qemu/capabilities/*.xml files whether or not the "iothread" object exists... I would think though that the reason why this is failing for you is that the kvm-spice emulator doesn't have the required capability (I forget if there's a magic incantation to ask the emulator image what it supports, especially for objects).