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

[Gleb Natapov]

On Tue, Oct 01, 2013 at 11:36:39AM -0500, Ben "Root" Anderson wrote:
> Agh, I forgot reply all.
> 
I have to re reply now :)

> Seems like something that should be changed, no? It would've saved me
> a lot of headache if there was a switch e.g.
> -optimize-for=[linux,winxp,
> win7,etc] that changed the defaults to be
> most accomodating to the specified OS as a guest.
> 
QEMU developers see it to be a management job. Management
(libvirt/virt-manager) knows what guest is and what optimal config is. I
am not sure they use -no-hpet for windows currently if they do not it
should be changed there.

> On Tue, Oct 1, 2013 at 11:33 AM, Gleb Natapov <address@hidden> wrote:
> > 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 <address@hidden> 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.

--
                        Gleb.