You have been subscribed to a public bug: Description =========== When running redhat or centos 7.6 guest os on vm, the cpu usage is very low on vm(100% idle), but on host, qemu-kvm reports 100% cpu busy usage.
After searching some related bugs report, I suspect that it is due to the clock settings in vm's domain xml. My Openstack cluster uses the default clock settings as follow: <clock offset='utc'> <timer name='rtc' tickpolicy='catchup'/> <timer name='pit' tickpolicy='delay'/> <timer name='hpet' present='no'/> </clock> And in this report, https://bugs.launchpad.net/qemu/+bug/1174654 it claims that <timer name='rtc' track='guest'/> can solve the 100% cpu usage problem when using Windows Image Guest OS, but I makes some tests, the solusion dose not work for me. Steps to reproduce ================== * create a vm using centos or redhat 7.6 image * using sar tool inside vm and host to check the cpu usage, and compare them Expected result =============== host's cpu usage report should be same with vm's cpu usage Actual result ============= vm's cpu usage is 100% idle, host's cpu usage is 100% busy Environment =========== 1. Exact version of OpenStack you are running. # rpm -qa | grep nova openstack-nova-compute-13.1.2-1.el7.noarch python2-novaclient-3.3.2-1.el7.noarch python-nova-13.1.2-1.el7.noarch openstack-nova-common-13.1.2-1.el7.noarch 2. Which hypervisor did you use? (For example: Libvirt + KVM, Libvirt + XEN, Hyper-V, PowerKVM, ...) What's the version of that? # libvirtd -V libvirtd (libvirt) 3.9.0 # /usr/libexec/qemu-kvm --version QEMU emulator version 2.6.0 (qemu-kvm-ev-2.6.0-28.el7_3.6.1), Copyright (c) 2003-2008 Fabrice Bellard Logs & Configs ============== The VM xml: <domain type='kvm' id='29'> <name>instance-00005022</name> <uuid>7f5a66a5-****-****-****-75dec****bbb</uuid> <metadata> <nova:instance xmlns:nova="http://openstack.org/xmlns/libvirt/nova/1.0"> <nova:package version="13.1.2-1.el7"/> <nova:name>*******</nova:name> <nova:creationTime>2019-05-20 03:08:46</nova:creationTime> <nova:flavor name="2d2dab36-****-****-****-246e9****110"> <nova:memory>2048</nova:memory> <nova:disk>12</nova:disk> <nova:swap>2048</nova:swap> <nova:ephemeral>0</nova:ephemeral> <nova:vcpus>1</nova:vcpus> </nova:flavor> <nova:owner> <nova:user uuid="********************">****</nova:user> <nova:project uuid="********************">****</nova:project> </nova:owner> <nova:root type="image" uuid="4496a420-****-****-****-b50f****ada3"/> </nova:instance> </metadata> <memory unit='KiB'>2097152</memory> <currentMemory unit='KiB'>2097152</currentMemory> <vcpu placement='static'>1</vcpu> <cputune> <shares>1024</shares> <vcpupin vcpu='0' cpuset='27'/> <emulatorpin cpuset='27'/> </cputune> <numatune> <memory mode='strict' nodeset='1'/> <memnode cellid='0' mode='strict' nodeset='1'/> </numatune> <resource> <partition>/machine</partition> </resource> <sysinfo type='smbios'> <system> <entry name='manufacturer'>Fedora Project</entry> <entry name='product'>OpenStack Nova</entry> <entry name='version'>13.1.2-1.el7</entry> <entry name='serial'>64ab0e89-****-****-****-05312ef66983</entry> <entry name='uuid'>7f5a66a5-****-****-****-75decaf82bbb</entry> <entry name='family'>Virtual Machine</entry> </system> </sysinfo> <os> <type arch='x86_64' machine='pc-i440fx-rhel7.3.0'>hvm</type> <boot dev='hd'/> <smbios mode='sysinfo'/> </os> <features> <acpi/> <apic/> </features> <cpu mode='custom' match='exact' check='full'> <model fallback='forbid'>IvyBridge</model> <topology sockets='1' cores='1' threads='1'/> <feature policy='require' name='hypervisor'/> <feature policy='require' name='arat'/> <feature policy='require' name='xsaveopt'/> <numa> <cell id='0' cpus='0' memory='2097152' unit='KiB'/> </numa> </cpu> <clock offset='utc'> <timer name='pit' tickpolicy='delay'/> <timer name='rtc' tickpolicy='catchup'/> <timer name='hpet' present='no'/> </clock> <on_poweroff>destroy</on_poweroff> <on_reboot>restart</on_reboot> <on_crash>destroy</on_crash> <devices> <emulator>/usr/libexec/qemu-kvm</emulator> <disk type='file' device='disk'> <driver name='qemu' type='raw' cache='none'/> <source file='/data/instances/7f5a66a5-****-****-****-75decaf82bbb/disk'/> <backingStore/> <target dev='vda' bus='virtio'/> <alias name='virtio-disk0'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/> </disk> <disk type='file' device='disk'> <driver name='qemu' type='raw' cache='none'/> <source file='/data/instances/7f5a66a5-****-****-****-75decaf82bbb/disk.swap'/> <backingStore/> <target dev='vdb' bus='virtio'/> <alias name='virtio-disk1'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/> </disk> <disk type='file' device='cdrom'> <driver name='qemu' type='raw' cache='none'/> <source file='/data/instances/7f5a66a5-****-****-****-75decaf82bbb/disk.config'/> <backingStore/> <target dev='hdd' bus='ide'/> <readonly/> <alias name='ide0-1-1'/> <address type='drive' controller='0' bus='1' target='0' unit='1'/> </disk> <controller type='usb' index='0' model='piix3-uhci'> <alias name='usb'/> <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='ide' index='0'> <alias name='ide'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1'/> </controller> <interface type='bridge'> <mac address='fa:16:3e:a6:ea:4f'/> <source bridge='brq52c66dc3-64'/> <bandwidth> <inbound average='102400'/> <outbound average='102400'/> </bandwidth> <target dev='tapa29e94e5-42'/> <model type='virtio'/> <alias name='net0'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/> </interface> <serial type='file'> <source path='/data/instances/7f5a66a5-****-****-****-75decaf82bbb/console.log'/> <target type='isa-serial' port='0'> <model name='isa-serial'/> </target> <alias name='serial0'/> </serial> <serial type='pty'> <source path='/dev/pts/10'/> <target type='isa-serial' port='1'> <model name='isa-serial'/> </target> <alias name='serial1'/> </serial> <console type='file'> <source path='/data/instances/7f5a66a5-****-****-****-75decaf82bbb/console.log'/> <target type='serial' port='0'/> <alias name='serial0'/> </console> <input type='tablet' bus='usb'> <alias name='input0'/> <address type='usb' bus='0' port='1'/> </input> <input type='mouse' bus='ps2'> <alias name='input1'/> </input> <input type='keyboard' bus='ps2'> <alias name='input2'/> </input> <graphics type='vnc' port='5910' autoport='yes' listen='0.0.0.0' keymap='en-us'> <listen type='address' address='0.0.0.0'/> </graphics> <video> <model type='cirrus' vram='16384' heads='1' primary='yes'/> <alias name='video0'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/> </video> <memballoon model='virtio'> <stats period='10'/> <alias name='balloon0'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/> </memballoon> </devices> <seclabel type='dynamic' model='dac' relabel='yes'> <label>+107:+107</label> <imagelabel>+107:+107</imagelabel> </seclabel> </domain> CPU Usage Report inside VM: # sar -u -P 0 1 5 Linux 3.10.0-957.el7.x86_64 (******) 05/20/2019 _x86_64_ (1 CPU) 11:34:40 AM CPU %user %nice %system %iowait %steal %idle 11:34:41 AM 0 0.00 0.00 0.00 0.00 0.00 100.00 11:34:42 AM 0 0.00 0.00 0.00 0.00 0.00 100.00 11:34:43 AM 0 0.00 0.00 0.00 0.00 0.00 100.00 11:34:44 AM 0 0.00 0.00 0.00 0.00 0.00 100.00 11:34:45 AM 0 0.00 0.00 0.00 0.00 0.00 100.00 Average: 0 0.00 0.00 0.00 0.00 0.00 100.00 CPU Usage Report ON HOST(the vm's cpu is pinned on host's no.27 physic cpu): # sar -u -P 27 1 5 Linux 3.10.0-862.el7.x86_64 (******) 05/20/2019 _x86_64_ (48 CPU) 11:34:40 AM CPU %user %nice %system %iowait %steal %idle 11:34:41 AM 27 100.00 0.00 0.00 0.00 0.00 0.00 11:34:42 AM 27 100.00 0.00 0.00 0.00 0.00 0.00 11:34:43 AM 27 100.00 0.00 0.00 0.00 0.00 0.00 11:34:44 AM 27 100.00 0.00 0.00 0.00 0.00 0.00 11:34:45 AM 27 100.00 0.00 0.00 0.00 0.00 0.00 Average: 27 100.00 0.00 0.00 0.00 0.00 0.00 clocksource inside VM: # cat /sys/devices/system/clocksource/clocksource0/current_clocksource kvm_clock ** Affects: qemu Importance: Undecided Status: New ** Tags: centos clock qemu-kvm redhat -- qemu-kvm takes 100% CPU when running redhat/centos 7.6 guest VM OS https://bugs.launchpad.net/bugs/1829696 You received this bug notification because you 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