Re: [Qemu-devel] [RFC PATCH 0/4] savevm: save vmsate with fixed size

[Wenchao Xia <xiawenc@linux.vnet.ibm.com>]

于 2013-3-5 20:04, Pavel Hrdina 写道:
> On 03/04/2013 04:04 PM, Wenchao Xia wrote:
>>
>>>> You probably get some improvements of the file size when the migration
>>>> takes a while, depending on how much of the memory actually has to be
>>>> saved. You might however end up with a lot more small writes instead of
>>>> some big ones before, which might hurt performance.
>>>>
>>>> Do you have any data about the resulting performance and file size?
>>>>
>>>    ah, an important issue I haven't test, thanks for tipping it, let
>>> me add code for migration to file, and have a test. It also
>>> can be optimized a bit in qemu_fseek(), but IMHO the optimization
>>> for small writes would better goto block layer either in qemu
>>> or underling components in system.
>>>
>> Hi,Juan
>>   talking about performance, in migration there are two buffer used,
>> one in qemu_file as static array, and one in migration as dynamic
>> allocated buffer,
>> should they be merged to avoid extra memcpy?
>>
>
> Hi Wenchao,
>
> This is already posted on qemu-devel list,
>
> http://lists.gnu.org/archive/html/qemu-devel/2013-02/msg04119.html
> http://lists.gnu.org/archive/html/qemu-devel/2013-02/msg04222.html
>
> Pavel
>
   Great, hope this can be upstream fast, thanks for tipping it.

-- 
Best Regards

Wenchao Xia