Re: [Qemu-devel] [Bug 599958] Re: Timedrift problems with Win7: hpet missing time drift fixups

[Gleb Natapov <gleb@redhat.com>]

On Tue, Oct 01, 2013 at 11:23:07AM -0500, Ben "Root" Anderson wrote:
> Fair enough in itself, but if HPET is known to have problems with
> arguably the most popular OS family to use as a guest, why is it
> enabled by default?
> 
Arguably :) But QEMU defaults are arguably far from been optimal for any
guest.

> On Tue, Oct 1, 2013 at 10:56 AM, Gleb Natapov <gleb@redhat.com> wrote:
> > On Tue, Oct 01, 2013 at 09:34:06AM -0000, Ben A wrote:
> >> Apparently this bug's still alive and kicking.
> >>
> > And no plans to fix it. Do not use hpet with windows guests this buys
> > you nothing.
> >
> >> There's an obvious clock skew problem on Windows 7; in the Date & Time
> >> dialog, the clock jumps through seconds visibly too fast.
> >>
> >> I also found a case where HPET bugs are causing a real problem: Terraria
> >> (dedicated server) seems to be relying on (something that relies on)
> >> HPET, and QEMU doesn't get it right. The result is a goofy and
> >> aggravating behavior I've nicknamed "Turbo Monsters of Doom" and it
> >> makes killing anything tougher than a normal zombie basically
> >> impossible.
> >>
> >> --
> >> You received this bug notification because you are a member of qemu-
> >> devel-ml, which is subscribed to QEMU.
> >> https://bugs.launchpad.net/bugs/599958
> >>
> >> Title:
> >>   Timedrift problems with Win7: hpet missing time drift fixups
> >>
> >> Status in QEMU:
> >>   Confirmed
> >>
> >> Bug description:
> >>   We've been finding timedrift issues witth Win7 under qemu-kvm on our
> >>   daily testing
> >>
> >>   kvm.qemu-kvm-git.smp2.Win7.64.timedrift.with_load   FAIL    1       Time drift too large after rest period: 38.63%
> >>   kvm.qemu-kvm-git.smp2.Win7.64.timedrift.with_reboot FAIL    1       Time drift too large at iteration 1: 17.77 seconds
> >>   kvm.qemu-kvm-git.smp2.Win7.64.timedrift.with_migration      FAIL    1       Time drift too large at iteration 2: 3.08 seconds
> >>
> >>   Steps to reproduce:
> >>
> >>   timedrift.with_load
> >>
> >>   1) Log into a guest.
> >>   2) Take a time reading from the guest and host.
> >>   3) Run load on the guest and host.
> >>   4) Take a second time reading.
> >>   5) Stop the load and rest for a while.
> >>   6) Take a third time reading.
> >>   7) If the drift immediately after load is higher than a user-
> >>       specified value (in %), fail.
> >>       If the drift after the rest period is higher than a user-specified value,
> >>       fail.
> >>
> >>   timedrift.with_migration
> >>
> >>   1) Log into a guest.
> >>   2) Take a time reading from the guest and host.
> >>   3) Migrate the guest.
> >>   4) Take a second time reading.
> >>   5) If the drift (in seconds) is higher than a user specified value, fail.
> >>
> >>   timedrift.with_reboot
> >>
> >>   1) Log into a guest.
> >>   2) Take a time reading from the guest and host.
> >>   3) Reboot the guest.
> >>   4) Take a second time reading.
> >>   5) If the drift (in seconds) is higher than a user specified value, fail.
> >>
> >>   This bug is to register those issues and keep an eye on them.
> >>
> >>   Attached, some logs from the autotest tests executed on the guest
> >>
> >> To manage notifications about this bug go to:
> >> https://bugs.launchpad.net/qemu/+bug/599958/+subscriptions
> >
> > --
> >                         Gleb.

--
			Gleb.