Re: [Qemu-devel] [RFC][PATCH 10/16 v6] run dump at the background

[Wen Congyang <wency@cn.fujitsu.com>]

At 02/15/2012 05:07 PM, Jan Kiszka Wrote:
> On 2012-02-15 04:47, Wen Congyang wrote:
>> At 02/15/2012 02:27 AM, Jan Kiszka Wrote:
>>> On 2012-02-14 19:05, Jan Kiszka wrote:
>>>> On 2012-02-09 04:28, Wen Congyang wrote:
>>>>> The new monitor command dump may take long time to finish. So we need run it
>>>>> at the background.
>>>>
>>>> How does it work? Like live migration, i.e. you retransmit (overwrite)
>>>> already written but then dirtied pages? Hmm... no.
>>>>
>>>> What does background mean then? What is the use case? What if the user
>>>> decides to resume the vm?
>>>
>>> OK, that is addressed in patch 15! I would suggest merging it into this
>>> patch. It makes sense to handle that case gracefully right from the
>>> beginning.
>>
>> OK, I will merge it.
>>
>>>
>>> OK, now I have some other question: What is the point of rate-limiting
>>> the dump? The guest is not running, thus not competing for bandwidth.
>>
>> I use bandwidth to try to control the writing speed. If we write the vmcore
>> to disk in a high speed, it may affect some other appilications which use
>> the same disk too.
> 
> Just like the guest of that particular VM can do. I don't think we need
> this level of control here, it will be provided (if required) at a
> different level, affecting the whole QEMU process. Removing the vmcore
> bandwidth control will simplify code and user interface.

OK. I will implementing it like this:
1. write 100ms
2. sleep 100ms(allow qemu to do the other things)
3. goto 1

Thanks
Wen Congyang
> 
> Jan
>