I did exactly the same sequence on Kaby Lake CPU and could not reproduce it. What is your host CPU? Thank you, Pasha On Mon, Jan 7, 2019 at 6:48 PM Dominique Martinet <asmadeus@xxxxxxxxxxxxx> wrote: > > Pavel Tatashin wrote on Mon, Jan 07, 2019: > > I could not reproduce the problem. Did you suspend to memory between > > wake ups? Does this time jump happen every time, even if your laptop > > sleeps for a minute? > > I'm not sure I understand "suspend to memory between the wake ups". > The full sequence is: > - start a VM (just in case, I let it boot till the end) > - suspend to memory (aka systemctl suspend) the host > - after resuming the host, soft reboot the VM (login through > serial/ssh/whatever and reboot or in the qemu console 'system_reset') > > I've just slept exactly one minute and reproduced again with the fedora > stock kernel now (4.19.13-300.fc29.x86_64) in the VM. > > Interestingly I'm not getting the same offset between multiple reboots > now despite not suspending again; but if I don't suspend I cannot seem > to get it to give an offset at all (only tried for a few minutes; this > might not be true) ; OTOH I pushed my luck further and even with a five > seconds sleep I'm getting a noticeable offset on first VM reboot after > resume: > > [ 0.000000] Hypervisor detected: KVM > [ 0.000000] kvm-clock: Using msrs 4b564d01 and 4b564d00 > [ 179.362163] kvm-clock: cpu 0, msr 13c01001, primary cpu clock > [ 179.362163] clocksource: kvm-clock: mask: 0xffffffffffffffff max_cycles: 0x1cd42e4dffb, max_idle_ns: 881590591483 ns > > Honestly not sure what more information I could give, I'll try on some > other hardware than my laptop (if I can get a server to resume after > suspend through ipmi or wake on lan); but I don't have anything I could > install ubuntu on to try their qemu's version... although I really don't > want to believe that's the difference... > > Thanks, > -- > Dominique
