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From: "Denis V. Lunev" <den-lists@parallels.com>
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Date: Wed, 7 Oct 2015 09:38:41 +0300
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Subject: Re: [Qemu-devel] Debugging Migration
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To: John Snow <jsnow@redhat.com>, qemu-devel <qemu-devel@nongnu.org>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>

On 10/07/2015 02:02 AM, John Snow wrote:
>
> On 10/06/2015 06:40 PM, Denis V. Lunev wrote:
>> On 10/06/2015 09:46 PM, John Snow wrote:
>>> Is there a convenient way of "pausing" or stalling a live migration to
>>> allow methodical testing of race conditions?
>>>
>>> I'd like to instrument something along the lines of:
>>>
>>> (1) Live migration begins.
>>> (2) migration is artificially halted or paused, but QEMU is allowed to
>>> run.
>>> (3) Some additional qtest/QMP commands are received and processed.
>>> (4) migration is allowed to resume.
>>>
>>> Does anyone have perhaps even test patches to instrument this sort of
>>> thing, or is it up to detective john to add it if he wants it?
>>>
>>> Thanks,
>>> --js
>>>
>> we have performed some experiments with migration "test mode".
>> The idea was to estimate the time to migrate and estimate
>> expected downtime for distributed resource management.
>> In this mode the migration was not performed but all stuff around
>> like dirty bitmap was touched.
>>
>> There are several patches for this in my queue but they are very
>> hackish.
>>
>> Will it help you?
>>
>> Den
> It certainly won't hurt me to look at them if you'll share :)
>
> --js

sent as
[RFC 0/8]  QEMUFile-way to gather VM's memory statistics

Sorry, I have lost threading accidentally.

Once again, that code is dirty and IMHO does not meet QEMU coding
standards at the moment.

Den