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

[Ben \"Root\" Anderson]

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?

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.