[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] Rethinking missed tick catchup
From: |
Clemens Kolbitsch |
Subject: |
Re: [Qemu-devel] Rethinking missed tick catchup |
Date: |
Wed, 12 Sep 2012 11:03:39 -0700 |
> On 2012-09-12 15:54, Anthony Liguori wrote:
>>
>> Hi,
>>
>> We've been running into a lot of problems lately with Windows guests and
>> I think they all ultimately could be addressed by revisiting the missed
>> tick catchup algorithms that we use. Mike and I spent a while talking
>> about it yesterday and I wanted to take the discussion to the list to
>> get some additional input.
>>
>> Here are the problems we're seeing:
>>
>> 1) Rapid reinjection can lead to time moving faster for short bursts of
>> time. We've seen a number of RTC watchdog BSoDs and it's possible
>> that at least one cause is reinjection speed.
>>
>> 2) When hibernating a host system, the guest gets is essentially paused
>> for a long period of time. This results in a very large tick catchup
>> while also resulting in a large skew in guest time.
>>
>> I've gotten reports of the tick catchup consuming a lot of CPU time
>> from rapid delivery of interrupts (although I haven't reproduced this
>> yet).
Guys,
not much that I can contribute to solving the problem, but I have a
bunch of VMs where this happens _every_ time I resume a snapshot (but
without hibernating). In case this could be a connected problem and
you need help testing a patch, I'm more than happy to help.
-Clemens
- Re: [Qemu-devel] Rethinking missed tick catchup, (continued)
Re: [Qemu-devel] Rethinking missed tick catchup, Luiz Capitulino, 2012/09/12
Re: [Qemu-devel] Rethinking missed tick catchup,
Clemens Kolbitsch <=