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

[Anthony Liguori]

-no-hpet works in every version of qemu/qemu-kvm that has included HPET
support.  RHEL disables HPET support by default unlike qemu and qemu-
kvm.

I've updated the bug priority and title to reflect what the issue is.

We only support edge triggered interrupts with HPET which seems to be
what most OSes use anyway.  We could potentially use the
reset_irq_delivered/get_irq_delivered APIC functions to implement
interrupt catch-up but I think it would be better to try to merge Jan's
generic IRQ delivered API first.

** Summary changed:

- Timedrift problems with Win7 + qemu-kvm
+ Timedrift problems with Win7: hpet missing time drift fixups

** Changed in: qemu
   Importance: Undecided => Wishlist

** Changed in: qemu
       Status: New => Confirmed

-- 
Timedrift problems with Win7: hpet missing time drift fixups
https://bugs.launchpad.net/bugs/599958
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.

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