I have switched a QEMU VM from 1 CPU to 2 with "-smp cpus=2". Immediately I am
getting lots of warnings like the following:
WARNING: TSC time went backwards by 2452936570 - change sysctl(7)
kern.timecounter?
The kern.timecounter variables are:
kern.timecounter.choice = TSC(q=3000, f=2999970000 Hz)
clockinterrupt(q=0, f=100 Hz) lapic(q=-100, f=1000004000 Hz) piixpm0(q=1000,
f=3579545 Hz) hpet0(q=2000, f=100000000 Hz) ACP
kern.timecounter.hardware = TSC
kern.timecounter.timestepwarnings = 0
Both the host and guest OS are:
NetBSD 10.1 (GENERIC) #0: Mon Dec 16 13:08:11 UTC 2024
mkre...@mkrepro.netbsd.org:/usr/src/sys/arch/amd64/compile/GENERIC amd64
According to
https://oliveryang.net/2015/09/pitfalls-of-TSC-usage/
TSC timekeeping is tricky, but I am not sure how to use that information to
solve the problem.
Is this a known issue? Any help is greatly appreciated.
Thanks a lot.
Cheers,
Brook
