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Bug
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Resolution: Done-Errata
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Major
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None
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False
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False
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CLOSED
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---
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Urgent
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None
Description of problem:
Reference: Bug 2125671
On a heterogeneous AMD cluster where each node has own tsc-frequency - the lowest frequency set to all nodes, as expected:
> $ for i in $(oc get node -o name);do echo $i;oc describe $i | grep tsc-freq; done
> node/cnv-qe-infra-25.cnvqe2.lab.eng.rdu2.redhat.com
> cpu-timer.node.kubevirt.io/tsc-frequency=1800000000
> scheduling.node.kubevirt.io/tsc-frequency-1800000000=true
> node/cnv-qe-infra-26.cnvqe2.lab.eng.rdu2.redhat.com
> cpu-timer.node.kubevirt.io/tsc-frequency=2500000000
> scheduling.node.kubevirt.io/tsc-frequency-1800000000=true
> scheduling.node.kubevirt.io/tsc-frequency-2500000000=true
> node/cnv-qe-infra-27.cnvqe2.lab.eng.rdu2.redhat.com
> cpu-timer.node.kubevirt.io/tsc-frequency=3000000000
> scheduling.node.kubevirt.io/tsc-frequency-1800000000=true
> scheduling.node.kubevirt.io/tsc-frequency-3000000000=true
And VM is asking for this frequency:
> bash-4.4$ virsh dumpxml 1 | grep tsc
> <timer name='tsc' frequency='1800000000'/>
However, VM may observe time jumps in logs right after run or after migration:
> Nov 15 13:22:28 rhel-tsc-10 systemd[4839]: Startup finished in 27ms.
> Nov 15 13:22:28 rhel-tsc-10 systemd[1]: Started User Manager for UID 1000.
> Nov 15 13:22:28 rhel-tsc-10 systemd[1]: Started Session 2 of user fedora.
> Nov 15 16:20:18 rhel-tsc-10 kernel: clocksource: timekeeping watchdog on CPU0: Marking clocksource 'tsc' as unstable because the skew is too large:
> Nov 15 16:20:18 rhel-tsc-10 kernel: clocksource: 'kvm-clock' wd_now: a007fc3247f wd_last: 5368ba9ca5 mask: ffffffffffffffff
> Nov 15 16:20:18 rhel-tsc-10 kernel: clocksource: 'tsc' cs_now: 1200f50582d2 cs_last: 96329863ce mask: ffffffffffffffff
> Nov 15 16:20:18 rhel-tsc-10 kernel: tsc: Marking TSC unstable due to clocksource watchdog
> Nov 15 16:20:18 rhel-tsc-10 systemd[1]: Starting dnf makecache...
and switching from tsc to kvm-clock:
> # cat /sys/devices/system/clocksource/clocksource0/current_clocksource
> kvm-clock
Version-Release number of selected component (if applicable):
4.11