I tested two newest QEMU versions these days, and sadly, the problem still happens.
I tried to find the reason why the qemu process take 100% usage of cpu, and collected some facts about it. I compared the facts with other normal vm's qemu process(who's cpu usage is normal) and didn't turn out any interesting result. Please give me some guides to debug this problem if you could, thanks very much. (The full content of facts is in the attachment) 1. ======the command line to start a VM====== # ps -ef |grep 1567284 | cat qemu 1567284 1 99 Jun21 ? 2-18:09:33 /usr/libexec/qemu-kvm -name guest=instance-0000530a,debug-threads=on -S -object secret,id=masterKey0,format=raw,file=/var/lib/libvirt/qemu/domain-1-instance-0000530a/master-key.aes -machine pc-i440fx-4.0,accel=kvm,usb=off,dump-guest-core=off -cpu IvyBridge -m 2048 -realtime mlock=off -smp 1,sockets=1,cores=1,threads=1 -object memory-backend-ram,id=ram-node0,size=2147483648,host-nodes=1,policy=bind -numa node,nodeid=0,cpus=0,memdev=ram-node0 -uuid 60d3ad85-1004-47e7-b2cb-5cf1a029ab47 -smbios type=1,manufacturer=Fedora Project,product=OpenStack Nova,version=13.1.2-1.el7,serial=c0700413-4a28-4e97-85c4-66fe3ec367dc,uuid=60d3ad85-1004-47e7-b2cb-5cf1a029ab47,family=Virtual Machine -no-user-config -nodefaults -chardev socket,id=charmonitor,path=/var/lib/libvirt/qemu/domain-1-instance-0000530a/monitor.sock,server,nowait -mon chardev=charmonitor,id=monitor,mode=control -rtc base=utc,driftfix=slew -global kvm-pit.lost_tick_policy=delay -no-hpet -no-shutdown -boot strict=on -device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 -drive file=/data/instances/60d3ad85-1004-47e7-b2cb-5cf1a029ab47/disk,format=raw,if=none,id=drive-virtio-disk0,cache=none -device virtio-blk-pci,scsi=off,bus=pci.0,addr=0x4,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=1 -drive file=/data/instances/60d3ad85-1004-47e7-b2cb-5cf1a029ab47/disk.swap,format=raw,if=none,id=drive-virtio-disk1,cache=none -device virtio-blk-pci,scsi=off,bus=pci.0,addr=0x5,drive=drive-virtio-disk1,id=virtio-disk1 -drive file=/data/instances/60d3ad85-1004-47e7-b2cb-5cf1a029ab47/disk.config,format=raw,if=none,id=drive-ide0-1-1,readonly=on,cache=none -device ide-cd,bus=ide.1,unit=1,drive=drive-ide0-1-1,id=ide0-1-1 -netdev tap,fd=27,id=hostnet0,vhost=on,vhostfd=29 -device virtio-net-pci,netdev=hostnet0,id=net0,mac=fa:16:3e:21:2c:70,bus=pci.0,addr=0x3 -add-fd set=2,fd=31 -chardev file,id=charserial0,path=/dev/fdset/2,append=on -device isa-serial,chardev=charserial0,id=serial0 -chardev pty,id=charserial1 -device isa-serial,chardev=charserial1,id=serial1 -device usb-tablet,id=input0,bus=usb.0,port=1 -vnc 0.0.0.0:0 -k en-us -device cirrus-vga,id=video0,bus=pci.0,addr=0x2 -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x6 -msg timestamp=on root 1567288 2 0 Jun21 ? 00:00:01 [vhost-1567284] root 1567291 2 0 Jun21 ? 00:00:00 [kvm-pit/1567284] 2. ===version of QEMU=== # /usr/libexec/qemu-kvm --version QEMU emulator version 4.0.0 Copyright (c) 2003-2019 Fabrice Bellard and the QEMU Project developers ===version of libvirt=== # libvirtd -V libvirtd (libvirt) 3.9.0 ===version of kernal=== # uname -a Linux txyz_40_92 3.10.0-862.el7.x86_64 #1 SMP Wed Mar 21 18:14:51 EDT 2018 x86_64 x86_64 x86_64 GNU/Linux Red Hat Enterprise Linux Server (3.10.0-862.el7.x86_64) 7.5 (Maipo) # modinfo kvm filename: /lib/modules/3.10.0-862.el7.x86_64/kernel/arch/x86/kvm/kvm.ko.xz license: GPL author: Qumranet retpoline: Y rhelversion: 7.5 srcversion: 8A3372406CDF0ACF69A0E58 depends: irqbypass intree: Y vermagic: 3.10.0-862.el7.x86_64 SMP mod_unload modversions signer: Red Hat Enterprise Linux kernel signing key sig_key: 51:73:02:3B:F8:16:37:D7:BF:3C:51:50:13:4E:EC:84:1B:96:FD:0B sig_hashalgo: sha256 parm: ignore_msrs:bool parm: min_timer_period_us:uint parm: kvmclock_periodic_sync:bool parm: tsc_tolerance_ppm:uint parm: lapic_timer_advance_ns:uint parm: vector_hashing:bool parm: halt_poll_ns:uint parm: halt_poll_ns_grow:uint parm: halt_poll_ns_shrink:uint 3. ===threads=== # ps -Lp 1567284 PID LWP TTY TIME CMD 1567284 1567284 ? 00:00:12 qemu-kvm 1567284 1567286 ? 00:00:00 call_rcu 1567284 1567289 ? 00:00:00 IO mon_iothread 1567284 1567290 ? 2-19:07:09 CPU 0/KVM 1567284 1567293 ? 00:00:00 vnc_worker 1567284 1637413 ? 00:00:00 worker ===top=== # top -H -p 1567284 top - 13:02:07 up 164 days, 21:53, 2 users, load average: 1.00, 1.01, 1.05 Threads: 6 total, 1 running, 5 sleeping, 0 stopped, 0 zombie %Cpu(s): 2.1 us, 0.0 sy, 0.0 ni, 97.9 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st KiB Mem : 26353241+total, 25289752+free, 2771140 used, 7863752 buff/cache KiB Swap: 8388604 total, 8388604 free, 0 used. 25926534+avail Mem scroll coordinates: y = 1/6 (tasks), x = 1/12 (fields) PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 1567290 qemu 20 0 6683072 647416 8336 R 99.7 0.2 4028:04 CPU 0/KVM 1567284 qemu 20 0 6683072 647416 8336 S 0.0 0.2 0:12.93 qemu-kvm 1567286 qemu 20 0 6683072 647416 8336 S 0.0 0.2 0:00.00 call_rcu 1567289 qemu 20 0 6683072 647416 8336 S 0.0 0.2 0:00.00 IO mon_iothread 1567293 qemu 20 0 6683072 647416 8336 S 0.0 0.2 0:00.27 vnc_worker 1637464 qemu 20 0 6683072 647416 8336 S 0.0 0.2 0:00.00 worker ===htop=== .... ** Attachment added: "100_cpu_usage_problem.txt" https://bugs.launchpad.net/qemu/+bug/1829696/+attachment/5272644/+files/100_cpu_usage_problem.txt -- You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1829696 Title: qemu-kvm takes 100% CPU when running redhat/centos 7.6 guest VM OS Status in QEMU: New Bug description: 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 To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/1829696/+subscriptions