KVM: High host CPU load after upgrading VM to windows 10 1803
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I'm running an Ubuntu 16.04 server with KVM/libvirt/qemu and Windows 10 virtual machine. After upgrading Windows 10 to the latest 1803 version (April 2018 Update), i noticed a slowdown in the VM responsiveness and a too high CPU load in the host.
The tests I did:
- "top" used on the host reports that the qemu-system-x86 process is taking 38-44% of CPU, while the VM is idle and reporting 4-6% of load inside windows process manager. When windows shows 50% of CPU load, the host shows 150-200% cpu load for the qemu-system-x86 process. This 8-10x increase in host CPU load does not occur with the old windows 10 1709 VM.
- "dstat" on the host reports a lot of system->csw, about 13k.
- I tested another system with the same setup with an AMD FX-4300, Ubuntu 17.10 dekstop + kvm, upgraded windows 10 to 1803 and I have the same problem of high host CPU and dstat-csw also on this machine.
- I took a third machine with an intel core i7, installed a new Ubuntu 18.04 desktop + kvm, installed a fresh new Windows 10, installed Virtio drivers available from here and I have the same high cpu problem.
What can I do? Am I using the right virtio drivers?
Thank you
virtualization windows-10 cpu kvm
asked May 9 at 11:07
giox069
213
add a comment |Â
up vote
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down vote
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I'm running an Ubuntu 16.04 server with KVM/libvirt/qemu and Windows 10 virtual machine. After upgrading Windows 10 to the latest 1803 version (April 2018 Update), i noticed a slowdown in the VM responsiveness and a too high CPU load in the host.
The tests I did:
- "top" used on the host reports that the qemu-system-x86 process is taking 38-44% of CPU, while the VM is idle and reporting 4-6% of load inside windows process manager. When windows shows 50% of CPU load, the host shows 150-200% cpu load for the qemu-system-x86 process. This 8-10x increase in host CPU load does not occur with the old windows 10 1709 VM.
- "dstat" on the host reports a lot of system->csw, about 13k.
- I tested another system with the same setup with an AMD FX-4300, Ubuntu 17.10 dekstop + kvm, upgraded windows 10 to 1803 and I have the same problem of high host CPU and dstat-csw also on this machine.
- I took a third machine with an intel core i7, installed a new Ubuntu 18.04 desktop + kvm, installed a fresh new Windows 10, installed Virtio drivers available from here and I have the same high cpu problem.
What can I do? Am I using the right virtio drivers?
Thank you
virtualization windows-10 cpu kvm
asked May 9 at 11:07
giox069
213
Are you sure you interpret this properly? If you have 8 Cores, and assign 8 cores to your vm, 25% load on windows will be a load of 2.0 on your host, which might show as 200%, because it's using 2 "CPU" by 100% each.
– davidbaumann
May 9 at 11:29
I have 4 cores on the host with Ubuntu 17.10, 2coresx2threads=4 on the host with Ubuntu 16.04. VM are configured all with 2 cores. I expect to find load of qemu-system-x86 on the host a bit higher than 2*windowsVMLoad. And this is still true on the backup I have of the vm with windows 10 1709: 3%windows cpu load gives 9% of qemu-system-x86 load on the ubuntu host. When I power off the old 1709VM and power on the new 1803 one, I wait it to be idle, and then windows has 6-7% load (never reached 3%), at the same time qemu-system-x86 on the host ranges from 44% to 54%.
– giox069
May 9 at 16:28
Also reported here by another user: lime-technology.com/forums/topic/71479-windows-10-vm-cpu-usage
– giox069
May 24 at 8:35
add a comment |Â
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up vote
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down vote
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I'm running an Ubuntu 16.04 server with KVM/libvirt/qemu and Windows 10 virtual machine. After upgrading Windows 10 to the latest 1803 version (April 2018 Update), i noticed a slowdown in the VM responsiveness and a too high CPU load in the host.
The tests I did:
- "top" used on the host reports that the qemu-system-x86 process is taking 38-44% of CPU, while the VM is idle and reporting 4-6% of load inside windows process manager. When windows shows 50% of CPU load, the host shows 150-200% cpu load for the qemu-system-x86 process. This 8-10x increase in host CPU load does not occur with the old windows 10 1709 VM.
- "dstat" on the host reports a lot of system->csw, about 13k.
- I tested another system with the same setup with an AMD FX-4300, Ubuntu 17.10 dekstop + kvm, upgraded windows 10 to 1803 and I have the same problem of high host CPU and dstat-csw also on this machine.
- I took a third machine with an intel core i7, installed a new Ubuntu 18.04 desktop + kvm, installed a fresh new Windows 10, installed Virtio drivers available from here and I have the same high cpu problem.
What can I do? Am I using the right virtio drivers?
Thank you
virtualization windows-10 cpu kvm
asked May 9 at 11:07
giox069
213
I'm running an Ubuntu 16.04 server with KVM/libvirt/qemu and Windows 10 virtual machine. After upgrading Windows 10 to the latest 1803 version (April 2018 Update), i noticed a slowdown in the VM responsiveness and a too high CPU load in the host.
The tests I did:
- "top" used on the host reports that the qemu-system-x86 process is taking 38-44% of CPU, while the VM is idle and reporting 4-6% of load inside windows process manager. When windows shows 50% of CPU load, the host shows 150-200% cpu load for the qemu-system-x86 process. This 8-10x increase in host CPU load does not occur with the old windows 10 1709 VM.
- "dstat" on the host reports a lot of system->csw, about 13k.
- I tested another system with the same setup with an AMD FX-4300, Ubuntu 17.10 dekstop + kvm, upgraded windows 10 to 1803 and I have the same problem of high host CPU and dstat-csw also on this machine.
- I took a third machine with an intel core i7, installed a new Ubuntu 18.04 desktop + kvm, installed a fresh new Windows 10, installed Virtio drivers available from here and I have the same high cpu problem.
What can I do? Am I using the right virtio drivers?
Thank you
virtualization windows-10 cpu kvm
asked May 9 at 11:07
giox069
213
asked May 9 at 11:07
giox069
213
asked May 9 at 11:07
giox069
213
asked May 9 at 11:07
giox069
213
213
Are you sure you interpret this properly? If you have 8 Cores, and assign 8 cores to your vm, 25% load on windows will be a load of 2.0 on your host, which might show as 200%, because it's using 2 "CPU" by 100% each.
– davidbaumann
May 9 at 11:29
I have 4 cores on the host with Ubuntu 17.10, 2coresx2threads=4 on the host with Ubuntu 16.04. VM are configured all with 2 cores. I expect to find load of qemu-system-x86 on the host a bit higher than 2*windowsVMLoad. And this is still true on the backup I have of the vm with windows 10 1709: 3%windows cpu load gives 9% of qemu-system-x86 load on the ubuntu host. When I power off the old 1709VM and power on the new 1803 one, I wait it to be idle, and then windows has 6-7% load (never reached 3%), at the same time qemu-system-x86 on the host ranges from 44% to 54%.
– giox069
May 9 at 16:28
Also reported here by another user: lime-technology.com/forums/topic/71479-windows-10-vm-cpu-usage
– giox069
May 24 at 8:35
add a comment |Â
Are you sure you interpret this properly? If you have 8 Cores, and assign 8 cores to your vm, 25% load on windows will be a load of 2.0 on your host, which might show as 200%, because it's using 2 "CPU" by 100% each.
– davidbaumann
May 9 at 11:29
I have 4 cores on the host with Ubuntu 17.10, 2coresx2threads=4 on the host with Ubuntu 16.04. VM are configured all with 2 cores. I expect to find load of qemu-system-x86 on the host a bit higher than 2*windowsVMLoad. And this is still true on the backup I have of the vm with windows 10 1709: 3%windows cpu load gives 9% of qemu-system-x86 load on the ubuntu host. When I power off the old 1709VM and power on the new 1803 one, I wait it to be idle, and then windows has 6-7% load (never reached 3%), at the same time qemu-system-x86 on the host ranges from 44% to 54%.
– giox069
May 9 at 16:28
Also reported here by another user: lime-technology.com/forums/topic/71479-windows-10-vm-cpu-usage
– giox069
May 24 at 8:35
Are you sure you interpret this properly? If you have 8 Cores, and assign 8 cores to your vm, 25% load on windows will be a load of 2.0 on your host, which might show as 200%, because it's using 2 "CPU" by 100% each.
– davidbaumann
May 9 at 11:29
Are you sure you interpret this properly? If you have 8 Cores, and assign 8 cores to your vm, 25% load on windows will be a load of 2.0 on your host, which might show as 200%, because it's using 2 "CPU" by 100% each.
– davidbaumann
May 9 at 11:29
I have 4 cores on the host with Ubuntu 17.10, 2coresx2threads=4 on the host with Ubuntu 16.04. VM are configured all with 2 cores. I expect to find load of qemu-system-x86 on the host a bit higher than 2*windowsVMLoad. And this is still true on the backup I have of the vm with windows 10 1709: 3%windows cpu load gives 9% of qemu-system-x86 load on the ubuntu host. When I power off the old 1709VM and power on the new 1803 one, I wait it to be idle, and then windows has 6-7% load (never reached 3%), at the same time qemu-system-x86 on the host ranges from 44% to 54%.
– giox069
May 9 at 16:28
I have 4 cores on the host with Ubuntu 17.10, 2coresx2threads=4 on the host with Ubuntu 16.04. VM are configured all with 2 cores. I expect to find load of qemu-system-x86 on the host a bit higher than 2*windowsVMLoad. And this is still true on the backup I have of the vm with windows 10 1709: 3%windows cpu load gives 9% of qemu-system-x86 load on the ubuntu host. When I power off the old 1709VM and power on the new 1803 one, I wait it to be idle, and then windows has 6-7% load (never reached 3%), at the same time qemu-system-x86 on the host ranges from 44% to 54%.
– giox069
May 9 at 16:28
Also reported here by another user: lime-technology.com/forums/topic/71479-windows-10-vm-cpu-usage
– giox069
May 24 at 8:35
Also reported here by another user: lime-technology.com/forums/topic/71479-windows-10-vm-cpu-usage
– giox069
May 24 at 8:35
add a comment |Â
1 Answer
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up vote
3
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Found someone with the same issue and a possible fix for it here:
https://forum.proxmox.com/threads/high-cpu-load-for-windows-10-guests-when-idle.44531/
Tested changing my own config, and setting hpet to yes in the vm xml fixed it for me.
<clock offset='localtime'>
<timer name='rtc' tickpolicy='catchup'/>
<timer name='pit' tickpolicy='delay'/>
<timer name='hpet' present='yes'/>
<timer name='hypervclock' present='yes'/>
</clock>
hpet part is important.
edited Aug 5 at 14:17
Michael Hampton
942719
answered Jun 17 at 16:45
MKHR
313
It works! Host CPU load is reduced a lot. I have also found another post on reddit which suggested to remove the following parameters from qemu commandline:-no-hpet-rtc base=localtime,driftfix=slew-global kvm-pit.lost_tick_policy=discardwhich translates into a slightly different .xml for libvirtd:<timer name='rtc' tickpolicy='delay'/><timer name='pit' tickpolicy='catchup'/><timer name='hpet' present='yes'/>Also with the above rtc/pit settings host cpu usage is reduced. VM general performances seems to be a bit lower than windows 1709.
– giox069
Jun 17 at 21:30
It also seems that <timer name='pit' tickpolicy='discard'/> (instead of 'delay') improves general VM performances. Ubuntu 16.04 does not support it. I upgraded to 18.04.
– giox069
Aug 8 at 22:54
for me enabling <synic state='on'> and <stimer state='on'> lowered the cpu usage to under 3%, with almost all cycles used by kernel kvm threads (looking at threads with top, qemu-kvm-ev uses zero cpu on rhel7.5 and kernel 4.16 from fedora28 for a q35 uefi win10 vm); source bugs.launchpad.net/qemu/+bug/1775702
– Costin Gușă
2 days ago
add a comment |Â
protected by Community♦ Aug 5 at 23:59
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Because it has attracted low-quality or spam answers that had to be removed, posting an answer now requires 10 reputation on this site (the association bonus does not count).
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1 Answer
1
active
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1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
3
down vote
Found someone with the same issue and a possible fix for it here:
https://forum.proxmox.com/threads/high-cpu-load-for-windows-10-guests-when-idle.44531/
Tested changing my own config, and setting hpet to yes in the vm xml fixed it for me.
<clock offset='localtime'>
<timer name='rtc' tickpolicy='catchup'/>
<timer name='pit' tickpolicy='delay'/>
<timer name='hpet' present='yes'/>
<timer name='hypervclock' present='yes'/>
</clock>
hpet part is important.
edited Aug 5 at 14:17
Michael Hampton
942719
answered Jun 17 at 16:45
MKHR
313
It works! Host CPU load is reduced a lot. I have also found another post on reddit which suggested to remove the following parameters from qemu commandline:-no-hpet-rtc base=localtime,driftfix=slew-global kvm-pit.lost_tick_policy=discardwhich translates into a slightly different .xml for libvirtd:<timer name='rtc' tickpolicy='delay'/><timer name='pit' tickpolicy='catchup'/><timer name='hpet' present='yes'/>Also with the above rtc/pit settings host cpu usage is reduced. VM general performances seems to be a bit lower than windows 1709.
– giox069
Jun 17 at 21:30
It also seems that <timer name='pit' tickpolicy='discard'/> (instead of 'delay') improves general VM performances. Ubuntu 16.04 does not support it. I upgraded to 18.04.
– giox069
Aug 8 at 22:54
for me enabling <synic state='on'> and <stimer state='on'> lowered the cpu usage to under 3%, with almost all cycles used by kernel kvm threads (looking at threads with top, qemu-kvm-ev uses zero cpu on rhel7.5 and kernel 4.16 from fedora28 for a q35 uefi win10 vm); source bugs.launchpad.net/qemu/+bug/1775702
– Costin Gușă
2 days ago
add a comment |Â
up vote
3
down vote
Found someone with the same issue and a possible fix for it here:
https://forum.proxmox.com/threads/high-cpu-load-for-windows-10-guests-when-idle.44531/
Tested changing my own config, and setting hpet to yes in the vm xml fixed it for me.
<clock offset='localtime'>
<timer name='rtc' tickpolicy='catchup'/>
<timer name='pit' tickpolicy='delay'/>
<timer name='hpet' present='yes'/>
<timer name='hypervclock' present='yes'/>
</clock>
hpet part is important.
edited Aug 5 at 14:17
Michael Hampton
942719
answered Jun 17 at 16:45
MKHR
313
It works! Host CPU load is reduced a lot. I have also found another post on reddit which suggested to remove the following parameters from qemu commandline:-no-hpet-rtc base=localtime,driftfix=slew-global kvm-pit.lost_tick_policy=discardwhich translates into a slightly different .xml for libvirtd:<timer name='rtc' tickpolicy='delay'/><timer name='pit' tickpolicy='catchup'/><timer name='hpet' present='yes'/>Also with the above rtc/pit settings host cpu usage is reduced. VM general performances seems to be a bit lower than windows 1709.
– giox069
Jun 17 at 21:30
It also seems that <timer name='pit' tickpolicy='discard'/> (instead of 'delay') improves general VM performances. Ubuntu 16.04 does not support it. I upgraded to 18.04.
– giox069
Aug 8 at 22:54
for me enabling <synic state='on'> and <stimer state='on'> lowered the cpu usage to under 3%, with almost all cycles used by kernel kvm threads (looking at threads with top, qemu-kvm-ev uses zero cpu on rhel7.5 and kernel 4.16 from fedora28 for a q35 uefi win10 vm); source bugs.launchpad.net/qemu/+bug/1775702
– Costin Gușă
2 days ago
add a comment |Â
up vote
3
down vote
up vote
3
down vote
Found someone with the same issue and a possible fix for it here:
https://forum.proxmox.com/threads/high-cpu-load-for-windows-10-guests-when-idle.44531/
Tested changing my own config, and setting hpet to yes in the vm xml fixed it for me.
<clock offset='localtime'>
<timer name='rtc' tickpolicy='catchup'/>
<timer name='pit' tickpolicy='delay'/>
<timer name='hpet' present='yes'/>
<timer name='hypervclock' present='yes'/>
</clock>
hpet part is important.
edited Aug 5 at 14:17
Michael Hampton
942719
answered Jun 17 at 16:45
MKHR
313
Found someone with the same issue and a possible fix for it here:
https://forum.proxmox.com/threads/high-cpu-load-for-windows-10-guests-when-idle.44531/
Tested changing my own config, and setting hpet to yes in the vm xml fixed it for me.
<clock offset='localtime'>
<timer name='rtc' tickpolicy='catchup'/>
<timer name='pit' tickpolicy='delay'/>
<timer name='hpet' present='yes'/>
<timer name='hypervclock' present='yes'/>
</clock>
hpet part is important.
edited Aug 5 at 14:17
Michael Hampton
942719
answered Jun 17 at 16:45
MKHR
313
edited Aug 5 at 14:17
Michael Hampton
942719
edited Aug 5 at 14:17
Michael Hampton
942719
edited Aug 5 at 14:17
Michael Hampton
942719
942719
answered Jun 17 at 16:45
MKHR
313
answered Jun 17 at 16:45
MKHR
313
answered Jun 17 at 16:45
MKHR
313
313
It works! Host CPU load is reduced a lot. I have also found another post on reddit which suggested to remove the following parameters from qemu commandline:-no-hpet-rtc base=localtime,driftfix=slew-global kvm-pit.lost_tick_policy=discardwhich translates into a slightly different .xml for libvirtd:<timer name='rtc' tickpolicy='delay'/><timer name='pit' tickpolicy='catchup'/><timer name='hpet' present='yes'/>Also with the above rtc/pit settings host cpu usage is reduced. VM general performances seems to be a bit lower than windows 1709.
– giox069
Jun 17 at 21:30
It also seems that <timer name='pit' tickpolicy='discard'/> (instead of 'delay') improves general VM performances. Ubuntu 16.04 does not support it. I upgraded to 18.04.
– giox069
Aug 8 at 22:54
for me enabling <synic state='on'> and <stimer state='on'> lowered the cpu usage to under 3%, with almost all cycles used by kernel kvm threads (looking at threads with top, qemu-kvm-ev uses zero cpu on rhel7.5 and kernel 4.16 from fedora28 for a q35 uefi win10 vm); source bugs.launchpad.net/qemu/+bug/1775702
– Costin Gușă
2 days ago
add a comment |Â
It works! Host CPU load is reduced a lot. I have also found another post on reddit which suggested to remove the following parameters from qemu commandline:-no-hpet-rtc base=localtime,driftfix=slew-global kvm-pit.lost_tick_policy=discardwhich translates into a slightly different .xml for libvirtd:<timer name='rtc' tickpolicy='delay'/><timer name='pit' tickpolicy='catchup'/><timer name='hpet' present='yes'/>Also with the above rtc/pit settings host cpu usage is reduced. VM general performances seems to be a bit lower than windows 1709.
– giox069
Jun 17 at 21:30
It also seems that <timer name='pit' tickpolicy='discard'/> (instead of 'delay') improves general VM performances. Ubuntu 16.04 does not support it. I upgraded to 18.04.
– giox069
Aug 8 at 22:54
for me enabling <synic state='on'> and <stimer state='on'> lowered the cpu usage to under 3%, with almost all cycles used by kernel kvm threads (looking at threads with top, qemu-kvm-ev uses zero cpu on rhel7.5 and kernel 4.16 from fedora28 for a q35 uefi win10 vm); source bugs.launchpad.net/qemu/+bug/1775702
– Costin Gușă
2 days ago
It works! Host CPU load is reduced a lot. I have also found another post on reddit which suggested to remove the following parameters from qemu commandline:
-no-hpet -rtc base=localtime,driftfix=slew -global kvm-pit.lost_tick_policy=discard which translates into a slightly different .xml for libvirtd: <timer name='rtc' tickpolicy='delay'/> <timer name='pit' tickpolicy='catchup'/> <timer name='hpet' present='yes'/> Also with the above rtc/pit settings host cpu usage is reduced. VM general performances seems to be a bit lower than windows 1709.– giox069
Jun 17 at 21:30
It works! Host CPU load is reduced a lot. I have also found another post on reddit which suggested to remove the following parameters from qemu commandline:
-no-hpet -rtc base=localtime,driftfix=slew -global kvm-pit.lost_tick_policy=discard which translates into a slightly different .xml for libvirtd: <timer name='rtc' tickpolicy='delay'/> <timer name='pit' tickpolicy='catchup'/> <timer name='hpet' present='yes'/> Also with the above rtc/pit settings host cpu usage is reduced. VM general performances seems to be a bit lower than windows 1709.– giox069
Jun 17 at 21:30
It also seems that <timer name='pit' tickpolicy='discard'/> (instead of 'delay') improves general VM performances. Ubuntu 16.04 does not support it. I upgraded to 18.04.
– giox069
Aug 8 at 22:54
It also seems that <timer name='pit' tickpolicy='discard'/> (instead of 'delay') improves general VM performances. Ubuntu 16.04 does not support it. I upgraded to 18.04.
– giox069
Aug 8 at 22:54
for me enabling <synic state='on'> and <stimer state='on'> lowered the cpu usage to under 3%, with almost all cycles used by kernel kvm threads (looking at threads with top, qemu-kvm-ev uses zero cpu on rhel7.5 and kernel 4.16 from fedora28 for a q35 uefi win10 vm); source bugs.launchpad.net/qemu/+bug/1775702
– Costin Gușă
2 days ago
for me enabling <synic state='on'> and <stimer state='on'> lowered the cpu usage to under 3%, with almost all cycles used by kernel kvm threads (looking at threads with top, qemu-kvm-ev uses zero cpu on rhel7.5 and kernel 4.16 from fedora28 for a q35 uefi win10 vm); source bugs.launchpad.net/qemu/+bug/1775702
– Costin Gușă
2 days ago
add a comment |Â
protected by Community♦ Aug 5 at 23:59
Thank you for your interest in this question.
Because it has attracted low-quality or spam answers that had to be removed, posting an answer now requires 10 reputation on this site (the association bonus does not count).
Would you like to answer one of these unanswered questions instead?
Are you sure you interpret this properly? If you have 8 Cores, and assign 8 cores to your vm, 25% load on windows will be a load of 2.0 on your host, which might show as 200%, because it's using 2 "CPU" by 100% each.
– davidbaumann
May 9 at 11:29
I have 4 cores on the host with Ubuntu 17.10, 2coresx2threads=4 on the host with Ubuntu 16.04. VM are configured all with 2 cores. I expect to find load of qemu-system-x86 on the host a bit higher than 2*windowsVMLoad. And this is still true on the backup I have of the vm with windows 10 1709: 3%windows cpu load gives 9% of qemu-system-x86 load on the ubuntu host. When I power off the old 1709VM and power on the new 1803 one, I wait it to be idle, and then windows has 6-7% load (never reached 3%), at the same time qemu-system-x86 on the host ranges from 44% to 54%.
– giox069
May 9 at 16:28
Also reported here by another user: lime-technology.com/forums/topic/71479-windows-10-vm-cpu-usage
– giox069
May 24 at 8:35